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Atre M, Joshi B, Babu J, Sawant S, Sharma S, Sankar TS. Origin, evolution, and maintenance of gene-strand bias in bacteria. Nucleic Acids Res 2024; 52:3493-3509. [PMID: 38442257 DOI: 10.1093/nar/gkae155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 02/06/2024] [Accepted: 02/19/2024] [Indexed: 03/07/2024] Open
Abstract
Gene-strand bias is a characteristic feature of bacterial genome organization wherein genes are preferentially encoded on the leading strand of replication, promoting co-orientation of replication and transcription. This co-orientation bias has evolved to protect gene essentiality, expression, and genomic stability from the harmful effects of head-on replication-transcription collisions. However, the origin, variation, and maintenance of gene-strand bias remain elusive. Here, we reveal that the frequency of inversions that alter gene orientation exhibits large variation across bacterial populations and negatively correlates with gene-strand bias. The density, distance, and distribution of inverted repeats show a similar negative relationship with gene-strand bias explaining the heterogeneity in inversions. Importantly, these observations are broadly evident across the entire bacterial kingdom uncovering inversions and inverted repeats as primary factors underlying the variation in gene-strand bias and its maintenance. The distinct catalytic subunits of replicative DNA polymerase have co-evolved with gene-strand bias, suggesting a close link between replication and the origin of gene-strand bias. Congruently, inversion frequencies and inverted repeats vary among bacteria with different DNA polymerases. In summary, we propose that the nature of replication determines the fitness cost of replication-transcription collisions, establishing a selection gradient on gene-strand bias by fine-tuning DNA sequence repeats and, thereby, gene inversions.
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Affiliation(s)
- Malhar Atre
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Bharat Joshi
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Jebin Babu
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Shabduli Sawant
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - Shreya Sharma
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
| | - T Sabari Sankar
- School of Biology, Indian Institute of Science Education and Research, Thiruvananthapuram, Kerala 695551, India
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2
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Charron P, Kang M. VariantDetective: an accurate all-in-one pipeline for detecting consensus bacterial SNPs and SVs. Bioinformatics 2024; 40:btae066. [PMID: 38366603 PMCID: PMC10898327 DOI: 10.1093/bioinformatics/btae066] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Revised: 01/16/2024] [Accepted: 02/14/2024] [Indexed: 02/18/2024] Open
Abstract
MOTIVATION Genomic variations comprise a spectrum of alterations, ranging from single nucleotide polymorphisms (SNPs) to large-scale structural variants (SVs), which play crucial roles in bacterial evolution and species diversification. Accurately identifying SNPs and SVs is beneficial for subsequent evolutionary and epidemiological studies. This study presents VariantDetective (VD), a novel, user-friendly, and all-in-one pipeline combining SNP and SV calling to generate consensus genomic variants using multiple tools. RESULTS The VD pipeline accepts various file types as input to initiate SNP and/or SV calling, and benchmarking results demonstrate VD's robustness and high accuracy across multiple tested datasets when compared to existing variant calling approaches. AVAILABILITY AND IMPLEMENTATION The source code, test data, and relevant information for VD are freely accessible at https://github.com/OLF-Bioinformatics/VariantDetective under the MIT License.
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Affiliation(s)
- Philippe Charron
- Ottawa Laboratory-Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Nepean, Ontario K2J 4S1, Canada
| | - Mingsong Kang
- Ottawa Laboratory-Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Nepean, Ontario K2J 4S1, Canada
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3
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DÜLGER D, EKİCİ S, DEMİRCİ M, YİĞİN A, BABACAN O. Tracking the footsteps of Burkholderia mallei: determination of the molecular differences and potential resistance genes. Turk J Med Sci 2023; 54:16-25. [PMID: 38812620 PMCID: PMC11031151 DOI: 10.55730/1300-0144.5761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 02/15/2024] [Accepted: 12/21/2023] [Indexed: 05/31/2024] Open
Abstract
Background/aim Chemical biological radiological nuclear threats are at an important point in the agenda of world health today, as they can cause mass deaths. B. mallei attracts attention as a potential biological warfare agent due to its features such as multidrug resistance, a rapid transmission mechanism via aerosol, the absence of a complete treatment protocol for the infection it causes, and the absence of an approved vaccine for protection against the bacteria. B. mallei suspect samples must be studied by experienced personnel in biosafety level III laboratories. B mallei is a difficult and troublesome pathogen to diagnose and many unknowns about B. mallei today. Therefore, the aim of the study was to determine the molecular differences and potential resistance genes of B mallei strains. Materials and methods Determination of the molecular differences and potential resistance genes of B mallei strains with new bioinformatics approaches by comparatively examining the data of 29 B mallei strains, 10 of which were isolated from Türkiye, on the genome list of the National Biotechnology Information Center (NCBI). Results According to the genome annotations of the origins, the origin containing the highest number of CDS which is 5172 was found as the 11th strain obtained in Türkiye in 1949. The origin with the highest number of pseudogenes was determined as 23,344 (China 7) origin. Two hundred and eighty-five pseudogenes found in this strain were obtained from a knee effusion in Myanmar. According to chromosome 2 data, B. mallei strain was determined as the most similar strain to ATCC 23344, line 11 with NCTC 10229 strain, and SAVP1 strain was determined as the least similar strain. When the antimicrobial resistance gene markers of the isolates included in the study were examined, amrA and amrB, qacG ade, Burkholderia pseudomallei Omp38 were found to be carrying. Conclusion In terms of public health, it was thought that the data obtained as a result of our study about B mallei, which is defined as a biological weapon, is very valuable for creating treatment protocols to be applied to possible epidemics in the future. In addition, the available genetic epidemiological data of these strains belonging to a category that is dangerous to work with in a laboratory environment were reviewed.
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Affiliation(s)
- Dilek DÜLGER
- Department of Medical Microbiology, Faculty of Medicine, Karabük University, Karabük,
Turkiye
| | - Seda EKİCİ
- Republic of Türkiye, the Ministry of Agriculture and Forestry, Veterinary Control Central Research Institute, Ankara,
Turkiye
| | - Mehmet DEMİRCİ
- Department of Medical Microbiology, Faculty of Medicine, Kırklareli University, Kırklareli,
Turkiye
| | - Akın YİĞİN
- Department of Genetics, Faculty of Veterinary, Harran University, Şanlıurfa,
Turkiye
| | - Orkun BABACAN
- Department of Veterinary, Kepsut Vocational School, Balıkesir University, Balıkesir,
Turkiye
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4
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Charron P, Gao R, Chmara J, Hoover E, Nadin-Davis S, Chauvin D, Hazelwood J, Makondo K, Duceppe MO, Kang M. Influence of genomic variations on glanders serodiagnostic antigens using integrative genomic and transcriptomic approaches. Front Vet Sci 2023; 10:1217135. [PMID: 38125681 PMCID: PMC10730941 DOI: 10.3389/fvets.2023.1217135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 11/20/2023] [Indexed: 12/23/2023] Open
Abstract
Glanders is a highly contagious and life-threatening zoonotic disease caused by Burkholderia mallei (B. mallei). Without an effective vaccine or treatment, early diagnosis has been regarded as the most effective method to prevent glanders transmission. Currently, the diagnosis of glanders is heavily reliant on serological tests. However, given that markedly different host immune responses can be elicited by genetically different strains of the same bacterial species, infection by B. mallei, whose genome is unstable and plastic, may result in various immune responses. This variability can make the serodiagnosis of glanders challenging. Therefore, there is a need for a comprehensive understanding and assessment of how B. mallei genomic variations impact the appropriateness of specific target antigens for glanders serodiagnosis. In this study, we investigated how genomic variations in the B. mallei genome affect gene content (gene presence/absence) and expression, with a special focus on antigens used or potentially used in serodiagnosis. In all the genome sequences of B. mallei isolates available in NCBI's RefSeq database (accessed in July 2023) and in-house sequenced samples, extensive small and large variations were observed when compared to the type strain ATCC 23344. Further pan-genome analysis of those assemblies revealed variations of gene content among all available genomes of B. mallei. Specifically, differences in gene content ranging from 31 to 715 genes with an average of 334 gene presence-absence variations were found in strains with complete or chromosome-level genome assemblies, using the ATCC 23344 strain as a reference. The affected genes included some encoded proteins used as serodiagnostic antigens, which were lost due mainly to structural variations. Additionally, a transcriptomic analysis was performed using the type strain ATCC 23344 and strain Zagreb which has been widely utilized to produce glanders antigens. In total, 388 significant differentially expressed genes were identified between these two strains, including genes related to bacterial pathogenesis and virulence, some of which were associated with genomic variations, particularly structural variations. To our knowledge, this is the first comprehensive study to uncover the impacts of genetic variations of B. mallei on its gene content and expression. These differences would have significant impacts on host innate and adaptive immunity, including antibody production, during infection. This study provides novel insights into B. mallei genetic variants, knowledge which will help to improve glanders serodiagnosis.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | - Mingsong Kang
- Ottawa Laboratory-Fallowfield, Canadian Food Inspection Agency, Ottawa, ON, Canada
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5
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Jitprasutwit N, Rungruengkitkun A, Lohitthai S, Reamtong O, Indrawattana N, Sookrung N, Sricharunrat T, Sukphopetch P, Chatratita N, Pumirat P. In Vitro Roles of Burkholderia Intracellular Motility A (BimA) in Infection of Human Neuroblastoma Cell Line. Microbiol Spectr 2023; 11:e0132023. [PMID: 37409935 PMCID: PMC10434047 DOI: 10.1128/spectrum.01320-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 06/16/2023] [Indexed: 07/07/2023] Open
Abstract
The bacterial pathogen Burkholderia pseudomallei causes human melioidosis, which can infect the brain, leading to encephalitis and brain abscesses. Infection of the nervous system is a rare condition but is associated with an increased risk of mortality. Burkholderia intracellular motility A (BimA) was reported to play an important role in the invasion and infection of the central nervous system in a mouse model. Thus, to gain insight of the cellular mechanisms underlying the pathogenesis of neurological melioidosis, we explored the human neuronal proteomics to identify the host factors that are up- and downregulated during Burkholderia infection. When infected the SH-SY5Y cells with B. pseudomallei K96243 wild-type (WT), 194 host proteins showed a fold change of >2 compared with uninfected cells. Moreover, 123 proteins showed a fold change of >2 when infected with a knockout bimA mutant (ΔbimA) mutant compared with WT. The differentially expressed proteins were mainly associated with metabolic pathways and pathways linked to human diseases. Importantly, we observed the downregulation of proteins in the apoptosis and cytotoxicity pathway, and in vitro investigation with the ΔbimA mutant revealed the association of BimA with the induction of these pathways. Additionally, we disclosed that BimA was not required for invasion into the neuron cell line but was necessary for effective intracellular replication and multinucleated giant cell (MNGC) formation. These findings show the extraordinary capacity of B. pseudomallei in subverting and interfering with host cellular systems to establish infection and extend our understanding of B. pseudomallei BimA involvement in the pathogenesis of neurological melioidosis. IMPORTANCE Neurological melioidosis, caused by Burkholderia pseudomallei, can result in severe neurological damage and enhance the mortality rate of melioidosis patients. We investigate the involvement of the virulent factor BimA, which mediates actin-based motility, in the intracellular infection of neuroblastoma SH-SY5Y cells. Using proteomics-based analysis, we provide a list of host factors exploited by B. pseudomallei. The expression level of selected downregulated proteins in neuron cells infected with the ΔbimA mutant was determined by quantitative reverse transcription-PCR and was consistent with our proteomic data. The role of BimA in the apoptosis and cytotoxicity of SH-SY5Y cells infected by B. pseudomallei was uncovered in this study. Additionally, our research demonstrates that BimA is required for successful intracellular survival and cell fusion upon infection of neuron cells. Our findings have significant implications for understanding the pathogenesis of B. pseudomallei infections and developing novel therapeutic strategies to combat this deadly disease.
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Affiliation(s)
- Niramol Jitprasutwit
- Center for Vaccine Development, Institute of Molecular Biosciences, Mahidol University, Nakhon Pathom, Thailand
| | - Amporn Rungruengkitkun
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Sanisa Lohitthai
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Onrapak Reamtong
- Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nitaya Indrawattana
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Nitat Sookrung
- Center of Research Excellence on Therapeutic Proteins and Antibody Engineering, Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
- Biomedical Research Incubator Unit, Department of Research, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand
| | - Thaniya Sricharunrat
- Pathology and Forensic Science Department, Chulabhorn Hospital, Chulabhorn Royal Academy, Bangkok, Thailand
| | - Passanesh Sukphopetch
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Narisara Chatratita
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
- Mahidol-Oxford Tropical Medicine Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
| | - Pornpan Pumirat
- Department of Microbiology and Immunology, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand
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6
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Suniga PAP, Mantovani C, Santos MG, Rieger JSG, Gaspar EB, Dos Santos FL, Mota RA, Chaves KP, Egito AA, Filho JCO, Nassar AFC, Dos Santos LR, Araújo FR. Molecular detection of Burkholderia mallei in different geographic regions of Brazil. Braz J Microbiol 2023; 54:1275-1285. [PMID: 37074557 PMCID: PMC10235260 DOI: 10.1007/s42770-023-00965-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 04/03/2023] [Indexed: 04/20/2023] Open
Abstract
Glanders is a contagious disease of equids caused by the Gram-negative bacterium Burkholderia mallei. In Brazil, the disease is considered to be reemerging and has been expanding, with records of equids with positive serology in most of the federative units. However, there are few reports describing the genotypic detection of the agent. This study demonstrated the detection of B. mallei by species-specific PCR directly from tissues or from bacterial cultures, followed by amplicon sequencing in equids (equines, mules, and asinines) with positive serology for glanders in all five geographic regions of Brazil. The molecular evidence of B. mallei infection in serologically positive equids in this study expands the possibility of strain isolation and the conduction of epidemiological characterizations based on molecular information. The microbiological detection of B. mallei in cultures from nasal and palate swabs, even in equids without clinical manifestations, raises the possibility of environmental elimination of the agent.
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Affiliation(s)
- Paula A Pereira Suniga
- MAI/DAI Scholarship, Federal University of Mato Grosso Do Sul, Cidade Universitária, Av. Costa E Silva, Campo Grande, MS, 79070-900, Brazil
- Postgraduate Program in Animal Science, Federal University of Mato Grosso Do Sul, Faculty of Veterinary Medicine and Animal Science-FAMEZ/UFMS, Av. Senador Filinto Muller, 2443, Campo Grande, MS, 79074-460, Brazil
| | - Cynthia Mantovani
- Embrapa Beef Cattle/Ministry of Agriculture, Livestock and Food Supply Scholarship, Embrapa Beef Cattle, Av. Rádio Maia, 830, Campo Grande, MS, 79106-550, Brazil
| | - Maria G Santos
- Embrapa Beef Cattle, Av. Rádio Maia, 830, Campo Grande, MS, 79106-550, Brazil
| | - Juliana S Gomes Rieger
- Embrapa Beef Cattle/Ministry of Agriculture, Livestock and Food Supply Scholarship, Embrapa Beef Cattle, Av. Rádio Maia, 830, Campo Grande, MS, 79106-550, Brazil
| | - Emanuelle B Gaspar
- Embrapa South Livestock, Rodovia BR-153, Km 632,9 Vila Industrial, Zona Rural, Caixa Postal 242, Bagé, RS, 96401-970, Brazil
| | | | - Rinaldo A Mota
- Department of Veterinary Medicine, Federal Rural University of Pernambuco, Recife, Pernambuco, Brazil
| | - Karla P Chaves
- Department of Veterinary Medicine, Federal University of Alagoas, Maceió, Alagoas, Brazil
| | - Andréa A Egito
- Postgraduate Program in Animal Science, Federal University of Mato Grosso Do Sul, Faculty of Veterinary Medicine and Animal Science-FAMEZ/UFMS, Av. Senador Filinto Muller, 2443, Campo Grande, MS, 79074-460, Brazil
- Embrapa Beef Cattle, Av. Rádio Maia, 830, Campo Grande, MS, 79106-550, Brazil
| | - José Carlos O Filho
- Veterinary Pathology Sector, Universidade Federal Do Recôncavo da Bahia (UFRB), Rua Rui Barbosa 710, Cruz Das Almas, BA, 44380-000, Brazil
| | - Alessandra F Castro Nassar
- Centro de Pesquisa Em Sanidade Animal, Instituto Biológico, Av. Conselheiro Rodrigues Alves, 1252, São Paulo, SP, 04014-002, Brazil
| | | | - Flábio R Araújo
- Embrapa Beef Cattle, Av. Rádio Maia, 830, Campo Grande, MS, 79106-550, Brazil
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7
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Somprasong N, Hagen JP, Sahl JW, Webb JR, Hall CM, Currie BJ, Wagner DM, Keim P, Schweizer HP. A conserved active site PenA β-lactamase Ambler motif specific for Burkholderia pseudomallei/B. mallei is likely responsible for intrinsic amoxicillin-clavulanic acid sensitivity and facilitates a simple diagnostic PCR assay for melioidosis. Int J Antimicrob Agents 2023; 61:106714. [PMID: 36640845 DOI: 10.1016/j.ijantimicag.2023.106714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 11/23/2022] [Accepted: 12/31/2022] [Indexed: 01/13/2023]
Abstract
Burkholderia pseudomallei is a soil- and water-dwelling Gram-negative bacterium that causes melioidosis in humans and animals. Amoxicillin-clavulanic acid (AMC) susceptibility has been hailed as an integral part of the screening algorithm for identification of B. pseudomallei, but the molecular basis for the inherent AMC susceptibility of this bacterium remains undefined. This study showed that B. pseudomallei (and the closely-related B. mallei) wild-type strains are the only Burkholderia spp. that contain a 70STSK73 PenA Ambler motif. This motif was present in >99.5% of 1820 analysed B. pseudomallei strains and 100% of 83 analysed B. mallei strains, and is proposed as the likely cause for their inherent AMC sensitivity. The authors developed a polymerase chain reaction (PCR) assay that specifically amplifies the penA70ST(S/F)K73-containing region from B. pseudomallei and B. mallei, but not from the remaining B. pseudomallei complex species or the 70STFK73 region from the closely-related penB of B. cepacia complex species. The abundance and purity of the 193-bp PCR fragment from putative B. pseudomallei isolates from clinical and environmental samples is likely sufficient for reliable confirmation of the presence of B. pseudomallei. The PCR assay is designed to be especially suited for use in resource-constrained areas. While not further explored in this study, the assay may allow diagnosis of putative B. mallei in culture isolates from animal and human samples.
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Affiliation(s)
- Nawarat Somprasong
- The Pathogen and Microbiome Institute, Northern Arizona University, 1395 S Knoles Dr. Flagstaff, AZ 86001-4073, USA
| | - Johannah P Hagen
- The Pathogen and Microbiome Institute, Northern Arizona University, 1395 S Knoles Dr. Flagstaff, AZ 86001-4073, USA
| | - Jason W Sahl
- The Pathogen and Microbiome Institute, Northern Arizona University, 1395 S Knoles Dr. Flagstaff, AZ 86001-4073, USA; Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Jessica R Webb
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia; Department of Microbiology and Immunology, Peter Doherty Institute for Infection and Immunity, The University of Melbourne, Melbourne, Australia
| | - Carina M Hall
- The Pathogen and Microbiome Institute, Northern Arizona University, 1395 S Knoles Dr. Flagstaff, AZ 86001-4073, USA
| | - Bart J Currie
- Global and Tropical Health Division, Menzies School of Health Research, Charles Darwin University, Darwin, Northern Territory, Australia; Department of Infectious Diseases and Northern Territory Medical Programme, Royal Darwin Hospital, Darwin, Northern Territory, Australia
| | - David M Wagner
- The Pathogen and Microbiome Institute, Northern Arizona University, 1395 S Knoles Dr. Flagstaff, AZ 86001-4073, USA; Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Paul Keim
- The Pathogen and Microbiome Institute, Northern Arizona University, 1395 S Knoles Dr. Flagstaff, AZ 86001-4073, USA; Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Herbert P Schweizer
- The Pathogen and Microbiome Institute, Northern Arizona University, 1395 S Knoles Dr. Flagstaff, AZ 86001-4073, USA; Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA.
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8
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Effective Therapeutic Options for Melioidosis: Antibiotics versus Phage Therapy. Pathogens 2022; 12:pathogens12010011. [PMID: 36678359 PMCID: PMC9863960 DOI: 10.3390/pathogens12010011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Revised: 12/08/2022] [Accepted: 12/16/2022] [Indexed: 12/24/2022] Open
Abstract
Melioidosis, also known as Whitmore's disease, is a potentially fatal infection caused by the Gram-negative bacteria Burkholderia pseudomallei with a mortality rate of 10-50%. The condition is a "glanders-like" illness prevalent in Southeast Asian and Northern Australian regions and can affect humans, animals, and sometimes plants. Melioidosis received the epithet "the great mimicker" owing to its vast spectrum of non-specific clinical manifestations, such as localised abscesses, septicaemia, pneumonia, septic arthritis, osteomyelitis, and encephalomyelitis, which often lead to misdiagnosis and ineffective treatment. To date, antibiotics remain the backbone of melioidosis treatment, which includes intravenous therapy with ceftazidime or meropenem, followed by oral therapy with TMP-SMX or amoxicillin/clavulanic acid and supported by adjunctive treatment. However, bacteria have developed resistance to a series of antibiotics, including clinically significant ones, during treatment. Therefore, phage therapy has gained unprecedented interest and has been proposed as an alternative treatment. Although no effective phage therapy has been published, the findings of experimental phage therapies suggest that the concept could be feasible. This article reviews the benefits and limitations of antibiotics and phage therapy in terms of established regimens, bacterial resistance, host specificity, and biofilm degradation.
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9
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Brangsch H, Singha H, Laroucau K, Elschner M. Sequence-based detection and typing procedures for Burkholderia mallei: Assessment and prospects. Front Vet Sci 2022; 9:1056996. [PMID: 36452150 PMCID: PMC9703372 DOI: 10.3389/fvets.2022.1056996] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2022] [Accepted: 10/26/2022] [Indexed: 10/28/2023] Open
Abstract
Although glanders has been eradicated in most of the developed world, the disease still persists in various countries such as Brazil, India, Pakistan, Bangladesh, Nepal, Iran, Bahrain, UAE and Turkey. It is one of the notifiable diseases listed by the World Organization for Animal Health. Occurrence of glanders imposes restriction on equestrian events and restricts equine movement, thus causing economic losses to equine industry. The genetic diversity and global distribution of the causing agent, Burkholderia (B.) mallei, have not been assessed in detail and are complicated by the high clonality of this organism. Among the identification and typing methods, PCR-based methods for distinguishing B. mallei from its close relative B. pseudomallei as well as genotyping using tandem repeat regions (MLVA) are established. The advent and continuous advancement of the sequencing techniques and the reconstruction of closed genomes enable the development of genome guided epidemiological tools. For achieving a higher genomic resolution, genotyping methods based on whole genome sequencing data can be employed, like genome-wide single nucleotide polymorphisms. One of the limitations in obtaining complete genomic sequences for further molecular characterization of B. mallei is its high GC content. In this review, we aim to provide an overview of the widely used detection and typing methods for B. mallei and illustrate gaps that still require development. The genomic features of Burkholderia, their high homology and clonality will be first described from a comparative genomics perspective. Then, the commonly used molecular detection (PCR systems) and typing systems (e.g., multilocus sequence typing, variable number of tandem repeat analysis) will be presented and put in perspective with recently developed genomic methods. Also, the increasing availability of B. mallei genomic sequences and evolution of the sequencing methods offers exciting prospects for further refinement of B. mallei typing, that could overcome the difficulties presently encountered with this particular bacterium.
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Affiliation(s)
- Hanka Brangsch
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut – Federal Research Institute for Animal Health, Jena, Germany
| | | | - Karine Laroucau
- Bacterial Zoonosis Unit, Animal Health Laboratory, French Food Agency (Anses), Maisons-Alfort, France
| | - Mandy Elschner
- Institute of Bacterial Infections and Zoonoses, Friedrich-Loeffler-Institut – Federal Research Institute for Animal Health, Jena, Germany
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10
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Abstract
The social amoeba Dictyostelium discoideum is a predatory soil protist frequently used for studying host-pathogen interactions. A subset of D. discoideum strains isolated from soil persistently carry symbiotic Paraburkholderia, recently formally described as P. agricolaris, P. bonniea, and P. hayleyella. The three facultative symbiont species of D. discoideum present a unique opportunity to study a naturally occurring symbiosis in a laboratory model protist. There is a large difference in genome size between P. agricolaris (8.7 million base pairs [Mbp]) versus P. hayleyella and P. bonniea (4.1 Mbp). We took a comparative genomics approach and compared the three genomes of D. discoideum symbionts to 12 additional Paraburkholderia genomes to test for genome evolution patterns that frequently accompany host adaptation. Overall, P. agricolaris is difficult to distinguish from other Paraburkholderia based on its genome size and content, but the reduced genomes of P. bonniea and P. hayleyella display characteristics indicative of genome streamlining rather than deterioration during adaptation to their protist hosts. In addition, D. discoideum-symbiont genomes have increased secretion system and motility genes that may mediate interactions with their host. Specifically, adjacent BurBor-like type 3 and T6SS-5-like type 6 secretion system operons shared among all three D. discoideum-symbiont genomes may be important for host interaction. Horizontal transfer of these secretion system operons within the amoeba host environment may have contributed to the unique ability of these symbionts to establish and maintain a symbiotic relationship with D. discoideum. IMPORTANCE Protists are a diverse group of typically single cell eukaryotes. Bacteria and archaea that form long-term symbiotic relationships with protists may evolve in additional ways than those in relationships with multicellular eukaryotes such as plants, animals, or fungi. Social amoebas are a predatory soil protist sometimes found with symbiotic bacteria living inside their cells. They present a unique opportunity to explore a naturally occurring symbiosis in a protist frequently used for studying host-pathogen interactions. We show that one amoeba-symbiont species is similar to other related bacteria in genome size and content, while the two reduced-genome-symbiont species show characteristics of genome streamlining rather than deterioration during adaptation to their host. We also identify sets of genes present in all three amoeba-symbiont genomes that are potentially used for host-symbiont interactions. Because the amoeba symbionts are distantly related, the amoeba host environment may be where these genes were shared among symbionts.
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11
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Abstract
The soil saprophyte, Burkholderia pseudomallei, is the causative agent of melioidosis, a disease endemic in South East Asia and northern Australia. Exposure to B. pseudomallei by either inhalation or inoculation can lead to severe disease. B. pseudomallei rapidly shifts from an environmental organism to an aggressive intracellular pathogen capable of rapidly spreading around the body. The expression of multiple virulence factors at every stage of intracellular infection allows for rapid progression of infection. Following invasion or phagocytosis, B. pseudomallei resists host-cell killing mechanisms in the phagosome, followed by escape using the type III secretion system. Several secreted virulence factors manipulate the host cell, while bacterial cells undergo a shift in energy metabolism allowing for overwhelming intracellular replication. Polymerisation of host cell actin into “actin tails” propels B. pseudomallei to the membranes of host cells where the type VI secretion system fuses host cells into multinucleated giant cells (MNGCs) to facilitate cell-to-cell dissemination. This review describes the various mechanisms used by B. pseudomallei to survive within cells.
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Affiliation(s)
- Nicole M Bzdyl
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
| | - Clare L Moran
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
| | - Justine Bendo
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
| | - Mitali Sarkar-Tyson
- The Marshall Centre for Infectious Diseases Research and Training, School of Biomedical Sciences, University of Western Australia, Perth, Western Australia, 6009, Australia
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12
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Pal G, Saxena S, Kumar K, Verma A, Sahu PK, Pandey A, White JF, Verma SK. Endophytic Burkholderia: Multifunctional roles in plant growth promotion and stress tolerance. Microbiol Res 2022; 265:127201. [PMID: 36167006 DOI: 10.1016/j.micres.2022.127201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 07/21/2022] [Accepted: 09/13/2022] [Indexed: 11/19/2022]
Abstract
The genus Burkholderia has proven potential in improving plant performance. In recent decades, a huge diversity of Burkholderia spp. have been reported with diverse capabilities of plant symbiosis which could be harnessed to enhance plant growth and development. Colonization of endophytic Burkholderia spp. have been extensively studied through techniques like advanced microscopy, fluorescent labelling, PCR based assays, etc., and found to be systemically distributed in plants. Thus, use of these biostimulant microbes holds the promise of improving quality and quantity of crops. The endophytic Burkholderia spp. have been found to support plant functions along with boosting nutrient availability, especially under stress. Endophytic Burkholderia spp. improve plant survival against deadly pathogens via mechanisms like competition, induced systemic resistance, and antibiosis. At the same time, they are reported to extend plant tolerance towards multiple abiotic stresses especially drought, salinity, and cold. Several attempts have been made to decipher the potential of Burkholderia spp. by genome mining, and these bacteria have been found to harbour genes for plant symbiosis and for providing multiple benefits to host plants. Characteristics specific for host recognition and nutrient acquisition were confirmed in endophytic Burkholderia by genomics and proteomics-based studies. This could pave the way for harnessing Burkholderia spp. for biotechnological applications like biotransformation, phytoremediation, insecticidal activity, antimicrobials, etc. All these make Burkholderia spp. a promising microbial agent in improving plant performance under multiple adversities. Thus, the present review highlights critical roles of endophytic Burkholderia spp., their colonization, alleviation of biotic and abiotic stresses, biotechnological applications and genomic insights.
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Affiliation(s)
- Gaurav Pal
- Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP, India
| | - Samiksha Saxena
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - Kanchan Kumar
- Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP, India
| | - Anand Verma
- Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP, India
| | - Pramod K Sahu
- National Bureau of Agriculturally Important Microorganisms, Mau, UP, India
| | - Ashutosh Pandey
- National Institute of Plant Genome Research, Aruna Asaf Ali Marg, New Delhi, India
| | - James F White
- Department of Plant Biology, Rutgers University, New Brunswick, NJ, USA.
| | - Satish K Verma
- Centre of Advanced Study in Botany, Banaras Hindu University, Varanasi, UP, India.
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13
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Appelt S, Rohleder AM, Jacob D, von Buttlar H, Georgi E, Mueller K, Wernery U, Kinne J, Joseph M, Jose SV, Scholz HC. Genetic diversity and spatial distribution of Burkholderia mallei by core genome-based multilocus sequence typing analysis. PLoS One 2022; 17:e0270499. [PMID: 35793321 PMCID: PMC9258848 DOI: 10.1371/journal.pone.0270499] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2022] [Accepted: 06/10/2022] [Indexed: 11/18/2022] Open
Abstract
Burkholderia mallei is the etiological agent of glanders, a highly contagious and often fatal disease in equids. Due to the high genetic clonality of B. mallei, high-resolution typing assays are necessary to differentiate between individual strains. Here we report on the development and validation of a robust and reproducible core genome-based Multi Locus Sequence Typing Assay (cgMLST) for B. mallei, which is based on 3328 gene targets and enables high-resolution typing at the strain level. The assay was validated using a set of 120 B. mallei genomes from public databases and 23 newly sequenced outbreak strains from in-house strain collections. In this cgMLST analysis, strains from different geographic regions were clearly distinguished by at least 70 allele differences, allowing spatial clustering while closely related and epidemiologically related strains were separated by only zero to three alleles. Neither the different sequencing technologies nor the assembly strategies had an influence on the cgMLST results. The developed cgMLST is highly robust, reproducible and can be used for outbreak investigations, source tracking and molecular characterization of new B. mallei isolates.
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Affiliation(s)
- Sandra Appelt
- Centre for Biological Threats and Special Pathogens (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Anna-Maria Rohleder
- Centre for Biological Threats and Special Pathogens (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Daniela Jacob
- Centre for Biological Threats and Special Pathogens (ZBS 2), Robert Koch Institute, Berlin, Germany
| | - Heiner von Buttlar
- Bundeswehr Institute of Microbiology, Department Bacteriology and Toxinology, Munich, Germany
| | - Enrico Georgi
- Bundeswehr Institute of Microbiology, Department Bacteriology and Toxinology, Munich, Germany
| | - Katharina Mueller
- Bundeswehr Institute of Microbiology, Department Bacteriology and Toxinology, Munich, Germany
| | - Ulrich Wernery
- Central Veterinary Research Laboratory, Dubai, United Arab Emirates
| | - Joerg Kinne
- Central Veterinary Research Laboratory, Dubai, United Arab Emirates
| | - Marina Joseph
- Central Veterinary Research Laboratory, Dubai, United Arab Emirates
| | | | - Holger C. Scholz
- Centre for Biological Threats and Special Pathogens (ZBS 2), Robert Koch Institute, Berlin, Germany
- Bundeswehr Institute of Microbiology, Department Bacteriology and Toxinology, Munich, Germany
- * E-mail:
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14
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Chieng R. Melioidosis. WIKIJOURNAL OF MEDICINE 2022. [DOI: 10.15347/wjm/2022.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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15
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Wu HP, Derilo RC, Chen HL, Li TR, Lagitnay RBJS, Chan YC, Chuang Y, Chuang DY. Injectisome T3SS subunits as potential chaperones in the extracellular export of Pectobacterium carotovorum subsp. carotovorum bacteriocins Carocin S1 and Carocin S3 secreted via flagellar T3SS. BMC Microbiol 2021; 21:345. [PMID: 34911446 PMCID: PMC8672553 DOI: 10.1186/s12866-021-02405-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 11/26/2021] [Indexed: 12/27/2022] Open
Abstract
Pectobacterium carotovorum subsp. carotovorum (Pcc) causes soft-rot disease in a wide variety of plants resulting in economic losses worldwide. It produces various types of bacteriocin to compete against related plant pathogens. Studies on how bacteriocins are extracellularly secreted are conducted to understand the mechanism of interbacterial competition. In this study, the secretion of the low-molecular-weight bacteriocins (LMWB) Carocin S1 and Carocin S3 produced by a multiple-bacteriocin producing strain of Pcc, 89-H-4, was investigated. Tn5 insertional mutagenesis was used to generate a mutant, TH22–6, incapable of LMWBs secretion. Sequence and homology analyses of the gene disrupted by transposon Tn5 insertion revealed that the gene sctT, an essential component of the injectisome type III secretion machinery (T3aSS), is required for the secretion of the bacteriocins. This result raised a question regarding the nature of the secretion mechanism of Pcc bacteriocins which was previously discovered to be secreted via T3bSS, a system that utilizes the bacterial flagellum for extracellular secretions. Our previous report has shown that bacteriocin Carocin S1 cannot be secreted by mutants that are defective of T3bSS-related genes such as flhA, flhC, flhD and fliC. We knocked out several genes making up the significant structural components of both T3aSS and T3bSS. The findings led us to hypothesize the potential roles of the T3aSS-related proteins, SctT, SctU and SctV, as flagellar T3SS chaperones in the secretion of Pcc bacteriocins. This current discovery and the findings of our previous study helped us to conceptualize a unique Type III secretion system for bacteriocin extracellular export which is a hybrid of the injectisome and flagellar secretion systems.
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Affiliation(s)
- Huang-Pin Wu
- Division of Pulmonary, Critical Care and Sleep Medicine, Chang Gung Memorial Hospital, Keelung, Taiwan.,College of Medicine, Chang Gung University, Taoyuan, Taiwan
| | - Reymund C Derilo
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., Taichung, 402, Taiwan.,College of Teacher Education, Nueva Vizcaya State University Bambang Campus, Bambang, Nueva Vizcaya, Philippines
| | - Han-Ling Chen
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., Taichung, 402, Taiwan
| | - Tzu-Rung Li
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., Taichung, 402, Taiwan
| | - Ruchi Briam James S Lagitnay
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., Taichung, 402, Taiwan.,College of Arts and Sciences, Nueva Vizcaya State University Bayombong Campus, Bayombong, Nueva Vizcaya, Philippines
| | - Yung-Chieh Chan
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., Taichung, 402, Taiwan
| | - Yutin Chuang
- Department of Entomology, National Chung Hsing University, Taichung City, Taiwan
| | - Duen-Yau Chuang
- Department of Chemistry, National Chung Hsing University, 145, Xingda Rd., Taichung, 402, Taiwan.
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16
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Amemiya K, Dankmeyer JL, Bernhards RC, Fetterer DP, Waag DM, Worsham PL, DeShazer D. Activation of Toll-Like Receptors by Live Gram-Negative Bacterial Pathogens Reveals Mitigation of TLR4 Responses and Activation of TLR5 by Flagella. Front Cell Infect Microbiol 2021; 11:745325. [PMID: 34888257 PMCID: PMC8650638 DOI: 10.3389/fcimb.2021.745325] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Accepted: 10/18/2021] [Indexed: 12/27/2022] Open
Abstract
Successful bacterial pathogens have evolved to avoid activating an innate immune system in the host that responds to the pathogen through distinct Toll-like receptors (TLRs). The general class of biochemical components that activate TLRs has been studied extensively, but less is known about how TLRs interact with the class of compounds that are still associated with the live pathogen. Accordingly, we examined the activation of surface assembled TLR 2, 4, and 5 with live Tier 1 Gram-negative pathogens that included Yersinia pestis (plague), Burkholderia mallei (glanders), Burkholderia pseudomallei (melioidosis), and Francisella tularensis (tularemia). We found that Y. pestis CO92 grown at 28°C activated TLR2 and TLR4, but at 37°C the pathogen activated primarily TLR2. Although B. mallei and B. pseudomallei are genetically related, the former microorganism activated predominately TLR4, while the latter activated predominately TLR2. The capsule of wild-type B. pseudomallei 1026b was found to mitigate the activation of TLR2 and TLR4 when compared to a capsule mutant. Live F. tularensis (Ft) Schu S4 did not activate TLR2 or 4, although the less virulent Ft LVS and F. novicida activated only TLR2. B. pseudomallei purified flagellin or flagella attached to the microorganism activated TLR5. Activation of TLR5 was abolished by an antibody to TLR5, or a mutation of fliC, or elimination of the pathogen by filtration. In conclusion, we have uncovered new properties of the Gram-negative pathogens, and their interaction with TLRs of the host. Further studies are needed to include other microorganism to extend our observations with their interaction with TLRs, and to the possibility of leading to new efforts in therapeutics against these pathogens.
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Affiliation(s)
- Kei Amemiya
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - Jennifer L Dankmeyer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - Robert C Bernhards
- Edgewood Chemical Biological Centre, Aberdeen Proving Ground, Edgewood, MD, United States
| | - David P Fetterer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - David M Waag
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - Patricia L Worsham
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
| | - David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Fort Detrick, Frederick, MD, United States
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17
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Syed I, Wooten RM. Interactions Between Pathogenic Burkholderia and the Complement System: A Review of Potential Immune Evasion Mechanisms. Front Cell Infect Microbiol 2021; 11:701362. [PMID: 34660335 PMCID: PMC8515183 DOI: 10.3389/fcimb.2021.701362] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 09/15/2021] [Indexed: 12/12/2022] Open
Abstract
The genus Burkholderia contains over 80 different Gram-negative species including both plant and human pathogens, the latter of which can be classified into one of two groups: the Burkholderia pseudomallei complex (Bpc) or the Burkholderia cepacia complex (Bcc). Bpc pathogens Burkholderia pseudomallei and Burkholderia mallei are highly virulent, and both have considerable potential for use as Tier 1 bioterrorism agents; thus there is great interest in the development of novel vaccines and therapeutics for the prevention and treatment of these infections. While Bcc pathogens Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia cepacia are not considered bioterror threats, the incredible impact these infections have on the cystic fibrosis community inspires a similar demand for vaccines and therapeutics for the prevention and treatment of these infections as well. Understanding how these pathogens interact with and evade the host immune system will help uncover novel therapeutic targets within these organisms. Given the important role of the complement system in the clearance of bacterial pathogens, this arm of the immune response must be efficiently evaded for successful infection to occur. In this review, we will introduce the Burkholderia species to be discussed, followed by a summary of the complement system and known mechanisms by which pathogens interact with this critical system to evade clearance within the host. We will conclude with a review of literature relating to the interactions between the herein discussed Burkholderia species and the host complement system, with the goal of highlighting areas in this field that warrant further investigation.
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Affiliation(s)
- Irum Syed
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States
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18
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Madhaiyan M, Selvakumar G, Alex TH, Cai L, Ji L. Plant Growth Promoting Abilities of Novel Burkholderia-Related Genera and Their Interactions With Some Economically Important Tree Species. FRONTIERS IN SUSTAINABLE FOOD SYSTEMS 2021. [DOI: 10.3389/fsufs.2021.618305] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A survey of bacterial endophytes associated with the leaves of oil palm and acacias resulted in the isolation of 19 bacterial strains belonging to the genera Paraburkholderia, Caballeronia, and Chitinasiproducens, which are now regarded as distinctively different from the parent genus Burkholderia. Most strains possessed one or more plant growth promotion (PGP) traits although nitrogenase activity was present in only a subset of the isolates. The diazotrophic Paraburkholderia tropica strain S39-2 with multiple PGP traits and the non-diazotrophic Chitinasiproducens palmae strain JS23T with a significant level of 1-aminocyclopropane-1-carboxylate (ACC) deaminase activity were selected to investigate the influence of bacterial inoculation on some economically important tree species. Microscopic examination revealed that P. tropica S39-2 was rhizospheric as well as endophytic while C. palmae JS23T was endophytic. P. tropica strain S39-2 significantly promoted the growth of oil palm, eucalyptus, and Jatropha curcas. Interestingly, the non-diazotrophic, non-auxin producing C. palmae JS23T strain also significantly promoted the growth of oil palm and eucalyptus although it showed negligible effect on J. curcas. Our results suggest that strains belonging to the novel Burkholderia-related genera widely promote plant growth via both N-independent and N-dependent mechanisms. Our results also suggest that the induction of defense response may prevent the colonization of an endophyte in plants.
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19
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Comparative genome analysis of Bacillus thuringiensis strain HD521 and HS18-1. Sci Rep 2021; 11:16590. [PMID: 34400725 PMCID: PMC8368016 DOI: 10.1038/s41598-021-96133-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2020] [Accepted: 07/22/2021] [Indexed: 02/07/2023] Open
Abstract
Bacillus thuringiensis (Bt) is an important biological insecticide used to management of different agricultural pests by producing toxic parasporal crystals proteins. Strain HD521 has an antagonistic effect against Rhizoctonia solani AG1IA, the causal agent of rice sheath blight. This strain with three cry7 genes can the formation of bipyramidal parasporal crystals (BPCs). BPCs are used for insecticidal activities against Henosepilachna vigintioctomaculata larva (Coleoptera). Strain HS18-1 contains different types of BPCs encoding genes and has effective toxicity for Lepidoptera and Diptera insects. Here we report the whole genome sequencing and assembly of HD521 and HS18-1 strains and analyzed the genome constitution covering virulence factors, types of plasmid, insertion sequences, and prophage sequences. The results showed that the genome of strain HD521 contains a circular chromosome and six circular plasmids, encoding eight types of virulence protein factors [Immune Inhibitor A, Hemolytic Enterotoxin, S-layer protein, Phospholipase C, Zwittermicin A-resistance protein, Metalloprotease, Chitinase, and N-acyl homoserine lactonase (AiiA)], four families of insertion sequence, and comprises six pro-phage sequences. The genome of strain HS18-1 contains one circular chromosome and nine circular plasmids, encoding five types of virulence protein factors [Hemolytic Enterotoxin, S-layer protein, Phospholipase C, Chitinase, and N-acyl homoserine lactonase (AiiA)] and four families of insertion sequence, and comprises of three pro-phage sequences. The obtained results will contribute to deeply understand the B. thuringiensis strain HD521 and HS18-1 at the genomic level.
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20
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Dyke JS, Huertas-Diaz MC, Michel F, Holladay NE, Hogan RJ, He B, Lafontaine ER. The Peptidoglycan-associated lipoprotein Pal contributes to the virulence of Burkholderia mallei and provides protection against lethal aerosol challenge. Virulence 2021; 11:1024-1040. [PMID: 32799724 PMCID: PMC7567441 DOI: 10.1080/21505594.2020.1804275] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022] Open
Abstract
Burkholderia mallei is a highly pathogenic bacterium that causes the fatal zoonosis glanders. The organism specifies multiple membrane proteins, which represent prime targets for the development of countermeasures given their location at the host-pathogen interface. We investigated one of these proteins, Pal, and discovered that it is involved in the ability of B. mallei to resist complement-mediated killing and replicate inside host cells in vitro, is expressed in vivo and induces antibodies during the course of infection, and contributes to virulence in a mouse model of aerosol infection. A mutant in the pal gene of the B. mallei wild-type strain ATCC 23344 was found to be especially attenuated, as BALB/c mice challenged with the equivalent of 5,350 LD50 completely cleared infection. Based on these findings, we tested the hypothesis that a vaccine containing the Pal protein elicits protective immunity against aerosol challenge. To achieve this, the pal gene was cloned in the vaccine vector Parainfluenza Virus 5 (PIV5) and mice immunized with the virus were infected with a lethal dose of B. mallei. These experiments revealed that a single dose of PIV5 expressing Pal provided 80% survival over a period of 40 days post-challenge. In contrast, only 10% of mice vaccinated with a PIV5 control virus construct survived infection. Taken together, our data establish that the Peptidoglycan-associated lipoprotein Pal is a critical virulence determinant of B. mallei and effective target for developing a glanders vaccine.
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Affiliation(s)
- Jeremy S Dyke
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine , Athens, GA, USA
| | | | - Frank Michel
- Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia College of Veterinary Medicine , Athens, GA, USA
| | - Nathan E Holladay
- Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia College of Veterinary Medicine , Athens, GA, USA
| | - Robert J Hogan
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine , Athens, GA, USA.,Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia College of Veterinary Medicine , Athens, GA, USA
| | - Biao He
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine , Athens, GA, USA
| | - Eric R Lafontaine
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine , Athens, GA, USA
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21
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Hasebe F. MetW regulates the enzymatic activity of MetX in Pseudomonas. Biosci Biotechnol Biochem 2021; 85:351-358. [PMID: 33604638 DOI: 10.1093/bbb/zbaa044] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2020] [Accepted: 10/05/2020] [Indexed: 11/13/2022]
Abstract
Methionine is a canonical amino acid. The protein MetX is a homoserine O-acyltransferase utilized in the methionine biosynthetic pathway. The metW gene is found adjacent to the metX gene in some bacteria, but its functions are unclear. In this study, I focused on the function of MetW and MetX from Pseudomonas aeruginosa (PaMetW and PaMetX). I demonstrated that PaMetW interacted with and activated the homoserine O-succinyltransferase (HST) activity of PaMetX. Furthermore, I elucidated that the HST activity of PaMetX in complex with PaMetW was inhibited by the addition of S-adenosyl-l-homocysteine (SAH), although PaMetX alone showed no feedback inhibition. Since PaMetW possesses a glycine-rich sequence annotated as a SAM/SAH binding site, I also investigated the relationship between this glycine-rich sequence and the inhibition caused by SAH. I revealed that alanine mutation of PaMetW Gly24 reduced the inhibitory effect of SAH. These results suggest that MetW is a regulatory protein of MetX.
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Affiliation(s)
- Fumihito Hasebe
- Graduate Division of Nutritional and Environmental Sciences, University of Shizuoka, Shizuoka, Japan
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22
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Burkholderia ubonensis High-Level Tetracycline Resistance Is Due to Efflux Pump Synergy Involving a Novel TetA(64) Resistance Determinant. Antimicrob Agents Chemother 2021; 65:AAC.01767-20. [PMID: 33318011 DOI: 10.1128/aac.01767-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023] Open
Abstract
Burkholderia ubonensis, a nonpathogenic soil bacterium belonging to the Burkholderia cepacia complex (Bcc), is highly resistant to some clinically significant antibiotics. The concern is that B. ubonensis may serve as a resistance reservoir for Bcc or B. pseudomallei complex (Bpc) organisms that are opportunistic human pathogens. Using a B. ubonensis strain highly resistant to tetracycline (MIC, ≥256 µg/ml), we identified and characterized tetA(64) that encodes a novel tetracycline-specific efflux pump of the major facilitator superfamily. TetA(64) and associated TetR(64) regulator expression are induced by tetracyclines. Although TetA(64) is the primary tetracycline and doxycycline resistance determinant, maximum tetracycline and doxycycline resistance requires synergy between TetA(64) and the nonspecific AmrAB-OprA resistance nodulation cell division efflux pump. TetA(64) does not efflux minocycline, tigecycline, and eravacycline. Comprehensive screening of genome sequences showed that TetA(64) is unequally distributed in the Bcc and absent from the Bpc. It is present in some major cystic fibrosis pathogens, like Burkholderia cenocepacia, but absent from others like Burkholderia multivorans The tetR(64)-tetA(64) genes are located in a region of chromosome 1 that is highly conserved in Burkholderia sp. Because there is no evidence for transposition, the tetR(64)-tetA(64) genes may have been acquired by homologous recombination after horizontal gene transfer. Although Burkholderia species contain a resident multicomponent efflux pump that allows them to respond to tetracyclines up to a certain concentration, the acquisition of the single-component TetA(64) by some species likely provides the synergy that these bacteria need to defend against high tetracycline concentrations in niche environments.
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A 'Build and Retrieve' methodology to simultaneously solve cryo-EM structures of membrane proteins. Nat Methods 2021; 18:69-75. [PMID: 33408407 PMCID: PMC7808410 DOI: 10.1038/s41592-020-01021-2] [Citation(s) in RCA: 61] [Impact Index Per Article: 20.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 11/16/2020] [Indexed: 11/26/2022]
Abstract
Single-particle cryo-electron microscopy (cryo-EM) has become a powerful technique in the field of structural biology. However, the inability to reliably produce pure, homogeneous membrane protein samples significantly hampers the progress of their structural determination. Here, we develop a bottom-up iterative method, designated “Build and Retrieve” (BaR), that allows us to identify and solve cryo-EM structures of a variety of inner and outer membrane proteins, including membrane protein complexes of different sizes and dimensions, from a heterogeneous, impure protein sample. We also employ the BaR methodology to elucidate structural information from E. coli K12 crude membrane and raw lysate. Our work demonstrates that it is possible to solve high-resolution structures of a number of relatively small (< 100 kDa) and less abundant (< 10%) unidentified membrane proteins within a single, heterogeneous sample. Importantly, these results highlight the potential of cryo-EM for systems structural proteomics.
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Syed I, Wooten RM. Interactions Between Pathogenic Burkholderia and the Complement System: A Review of Potential Immune Evasion Mechanisms. Front Cell Infect Microbiol 2021. [PMID: 34660335 DOI: 10.1086/69216810.3389/fcimb.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/07/2023] Open
Abstract
The genus Burkholderia contains over 80 different Gram-negative species including both plant and human pathogens, the latter of which can be classified into one of two groups: the Burkholderia pseudomallei complex (Bpc) or the Burkholderia cepacia complex (Bcc). Bpc pathogens Burkholderia pseudomallei and Burkholderia mallei are highly virulent, and both have considerable potential for use as Tier 1 bioterrorism agents; thus there is great interest in the development of novel vaccines and therapeutics for the prevention and treatment of these infections. While Bcc pathogens Burkholderia cenocepacia, Burkholderia multivorans, and Burkholderia cepacia are not considered bioterror threats, the incredible impact these infections have on the cystic fibrosis community inspires a similar demand for vaccines and therapeutics for the prevention and treatment of these infections as well. Understanding how these pathogens interact with and evade the host immune system will help uncover novel therapeutic targets within these organisms. Given the important role of the complement system in the clearance of bacterial pathogens, this arm of the immune response must be efficiently evaded for successful infection to occur. In this review, we will introduce the Burkholderia species to be discussed, followed by a summary of the complement system and known mechanisms by which pathogens interact with this critical system to evade clearance within the host. We will conclude with a review of literature relating to the interactions between the herein discussed Burkholderia species and the host complement system, with the goal of highlighting areas in this field that warrant further investigation.
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Affiliation(s)
- Irum Syed
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States
| | - R Mark Wooten
- Department of Medical Microbiology and Immunology, University of Toledo College of Medicine and Life Sciences, Toledo, OH, United States
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Unique Features of Tandem Repeats in Bacteria. J Bacteriol 2020; 202:JB.00229-20. [PMID: 32839174 DOI: 10.1128/jb.00229-20] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2020] [Accepted: 08/17/2020] [Indexed: 02/06/2023] Open
Abstract
DNA tandem repeats, or satellites, are well described in eukaryotic species, but little is known about their prevalence across prokaryotes. Here, we performed the most complete characterization to date of satellites in bacteria. We identified 121,638 satellites from 12,233 fully sequenced and assembled bacterial genomes with a very uneven distribution. We also determined the families of satellites which have a related sequence. There are 85 genomes that are particularly satellite rich and contain several families of satellites of yet unknown function. Interestingly, we only found two main types of noncoding satellites, depending on their repeat sizes, 22/44 or 52 nucleotides (nt). An intriguing feature is the constant size of the repeats in the genomes of different species, whereas their sequences show no conservation. Individual species also have several families of satellites with the same repeat length and different sequences. This result is in marked contrast with previous findings in eukaryotes, where noncoding satellites of many sizes are found in any species investigated. We describe in greater detail these noncoding satellites in the spirochete Leptospira interrogans and in several bacilli. These satellites undoubtedly play a specific role in the species which have acquired them. We discuss the possibility that they represent binding sites for transcription factors not previously described or that they are involved in the stabilization of the nucleoid through interaction with proteins.IMPORTANCE We found an enigmatic group of noncoding satellites in 85 bacterial genomes with a constant repeat size but variable sequence. This pattern of DNA organization is unique and had not been previously described in bacteria. These findings strongly suggest that satellite size in some bacteria is under strong selective constraints and thus that satellites are very likely to play a fundamental role. We also provide a list and properties of all satellites in 12,233 genomes, which may be used for further genomic analysis.
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Norris MH, Tran HTT, Walker MA, Bluhm AP, Zincke D, Trung TT, Thi NV, Thi NP, Schweizer HP, Unger F, Blackburn JK, Hang NTT. Distribution of Serological Response to Burkholderia pseudomallei in Swine from Three Provinces of Vietnam. INTERNATIONAL JOURNAL OF ENVIRONMENTAL RESEARCH AND PUBLIC HEALTH 2020; 17:ijerph17145203. [PMID: 32708490 PMCID: PMC7399857 DOI: 10.3390/ijerph17145203] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/09/2020] [Accepted: 07/16/2020] [Indexed: 01/18/2023]
Abstract
(1) Background: Burkholderia pseudomallei is an environmentally mediated saprophytic pathogen that can cause severe disease in humans. It is well known that B. pseudomallei survives in tropical moist soil environments worldwide, but melioidosis is gaining recognition as a public and veterinary health issue in Vietnam. The contribution of animals to human disease is unknown, necessitating further investigation. (2) Methods: Swine sera were collected from two populations, one grazing and one commercially farmed, from three provinces in Vietnam. ELISAs utilizing B. pseudomallei capsular polysaccharide (CPS), outer polysaccharide (OPS), and Hcp1 protein were used to screen serum samples. Positive samples were mapped to the commune level. Seroprevalence calculations and pig population estimates were used to approximate number of swine exposures per commune. (3) Results: Grazing pigs from Hoa Binh had significantly higher seropositivity levels (11.4%, 95% CI: 9.7–13.1) compared to farmed pigs from Ha Tinh and Nghe An (4%, 95% CI: 3.3–4.7). Average swine seropositivity rates were ~6.3% (95% CI: 5–7.9), higher than previously identified in Vietnam (~0.88%). (4) Conclusions: Initial serological sampling identified a significant number of seropositive and potential melioidosis infections occurring in swine in Vietnam. This work is a critical step in understanding the role swine may play in the epidemiology of human melioidosis in Vietnam.
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Affiliation(s)
- Michael H. Norris
- Spatial Epidemiology and Ecology Research Lab, Department of Geography, University of Florida, Gainesville, FL 32611, USA; (M.A.W.); (A.P.B.); (D.Z.); (J.K.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA;
- Correspondence:
| | - Hang Thi Thu Tran
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (H.T.T.T.); (N.V.T.); (N.P.T.); (N.T.T.H.)
| | - Morgan A. Walker
- Spatial Epidemiology and Ecology Research Lab, Department of Geography, University of Florida, Gainesville, FL 32611, USA; (M.A.W.); (A.P.B.); (D.Z.); (J.K.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA;
| | - Andrew P. Bluhm
- Spatial Epidemiology and Ecology Research Lab, Department of Geography, University of Florida, Gainesville, FL 32611, USA; (M.A.W.); (A.P.B.); (D.Z.); (J.K.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA;
| | - Diansy Zincke
- Spatial Epidemiology and Ecology Research Lab, Department of Geography, University of Florida, Gainesville, FL 32611, USA; (M.A.W.); (A.P.B.); (D.Z.); (J.K.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA;
| | - Trinh Thanh Trung
- VNU-Institute of Microbiology and Biotechnology, Vietnam National University, Hanoi 10000, Vietnam;
| | - Nga Vu Thi
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (H.T.T.T.); (N.V.T.); (N.P.T.); (N.T.T.H.)
| | - Ngoc Pham Thi
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (H.T.T.T.); (N.V.T.); (N.P.T.); (N.T.T.H.)
| | - Herbert P. Schweizer
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA;
- Department of Molecular Genetics and Microbiology, University of Florida, Gainesville, FL 32611, USA
| | - Fred Unger
- International Livestock Research Institute, Hanoi 10000, Vietnam;
| | - Jason K. Blackburn
- Spatial Epidemiology and Ecology Research Lab, Department of Geography, University of Florida, Gainesville, FL 32611, USA; (M.A.W.); (A.P.B.); (D.Z.); (J.K.B.)
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA;
| | - Nguyen Thi Thu Hang
- National Institute of Veterinary Research, Hanoi 10000, Vietnam; (H.T.T.T.); (N.V.T.); (N.P.T.); (N.T.T.H.)
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A Polar Flagellar Transcriptional Program Mediated by Diverse Two-Component Signal Transduction Systems and Basal Flagellar Proteins Is Broadly Conserved in Polar Flagellates. mBio 2020; 11:mBio.03107-19. [PMID: 32127455 PMCID: PMC7064773 DOI: 10.1128/mbio.03107-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Relative to peritrichous bacteria, polar flagellates possess regulatory systems that order flagellar gene transcription differently and produce flagella in specific numbers only at poles. How transcriptional and flagellar biogenesis regulatory systems are interlinked to promote the correct synthesis of polar flagella in diverse species has largely been unexplored. We found evidence for many Gram-negative polar flagellates encoding two-component signal transduction systems with activity linked to the formation of flagellar type III secretion systems to enable production of flagellar rod and hook proteins at a discrete, subsequent stage during flagellar assembly. This polar flagellar transcriptional program assists, in some manner, the FlhF/FlhG flagellar biogenesis regulatory system, which forms specific flagellation patterns in polar flagellates in maintaining flagellation and motility when activity of FlhF or FlhG might be altered. Our work provides insight into the multiple regulatory processes required for polar flagellation. Bacterial flagella are rotating nanomachines required for motility. Flagellar gene expression and protein secretion are coordinated for efficient flagellar biogenesis. Polar flagellates, unlike peritrichous bacteria, commonly order flagellar rod and hook gene transcription as a separate step after production of the MS ring, C ring, and flagellar type III secretion system (fT3SS) core proteins that form a competent fT3SS. Conserved regulatory mechanisms in diverse polar flagellates to create this polar flagellar transcriptional program have not been thoroughly assimilated. Using in silico and genetic analyses and our previous findings in Campylobacter jejuni as a foundation, we observed a large subset of Gram-negative bacteria with the FlhF/FlhG regulatory system for polar flagellation to possess flagellum-associated two-component signal transduction systems (TCSs). We present data supporting a general theme in polar flagellates whereby MS ring, rotor, and fT3SS proteins contribute to a regulatory checkpoint during polar flagellar biogenesis. We demonstrate that Vibrio cholerae and Pseudomonas aeruginosa require the formation of this regulatory checkpoint for the TCSs to directly activate subsequent rod and hook gene transcription, which are hallmarks of the polar flagellar transcriptional program. By reprogramming transcription in V. cholerae to more closely follow the peritrichous flagellar transcriptional program, we discovered a link between the polar flagellar transcription program and the activity of FlhF/FlhG flagellar biogenesis regulators in which the transcriptional program allows polar flagellates to continue to produce flagella for motility when FlhF or FlhG activity may be altered. Our findings integrate flagellar transcriptional and biogenesis regulatory processes involved in polar flagellation in many species.
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Thapa SS, Grove A. Do Global Regulators Hold the Key to Production of Bacterial Secondary Metabolites? Antibiotics (Basel) 2019; 8:antibiotics8040160. [PMID: 31547528 PMCID: PMC6963729 DOI: 10.3390/antibiotics8040160] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 12/18/2022] Open
Abstract
The emergence of multiple antibiotic resistant bacteria has pushed the available pool of antibiotics to the brink. Bacterial secondary metabolites have long been a valuable resource in the development of antibiotics, and the genus Burkholderia has recently emerged as a source of novel compounds with antibacterial, antifungal, and anti-cancer activities. Genome mining has contributed to the identification of biosynthetic gene clusters, which encode enzymes that are responsible for synthesis of such secondary metabolites. Unfortunately, these large gene clusters generally remain silent or cryptic under normal laboratory settings, which creates a hurdle in identification and isolation of these compounds. Various strategies, such as changes in growth conditions and antibiotic stress, have been applied to elicit the expression of these cryptic gene clusters. Although a number of compounds have been isolated from different Burkholderia species, the mechanisms by which the corresponding gene clusters are regulated remain poorly understood. This review summarizes the activity of well characterized secondary metabolites from Burkholderia species and the role of local regulators in their synthesis, and it highlights recent evidence for the role of global regulators in controlling production of secondary metabolites. We suggest that targeting global regulators holds great promise for the awakening of cryptic gene clusters and for developing better strategies for discovery of novel antibiotics.
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Affiliation(s)
- Sudarshan Singh Thapa
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
| | - Anne Grove
- Department of Biological Sciences, Louisiana State University, Baton Rouge, LA 70803, USA.
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Subirana JA, Messeguer X. Satellites in the prokaryote world. BMC Evol Biol 2019; 19:181. [PMID: 31533616 PMCID: PMC6749651 DOI: 10.1186/s12862-019-1504-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2019] [Accepted: 08/28/2019] [Indexed: 11/10/2022] Open
Abstract
Background Satellites or tandem repeats are very abundant in many eukaryotic genomes. Occasionally they have been reported to be present in some prokaryotes, but to our knowledge there is no general comparative study on their occurrence. For this reason we present here an overview of the distribution and properties of satellites in a set of representative species. Our results provide novel insights into the evolutionary relationship between eukaryotes, Archaea and Bacteria. Results We have searched all possible satellites present in the NCBI reference group of genomes in Archaea (142 species) and in Bacteria (119 species), detecting 2735 satellites in Archaea and 1067 in Bacteria. We have found that the distribution of satellites is very variable in different organisms. The archaeal Methanosarcina class stands out for the large amount of satellites in their genomes. Satellites from a few species have similar characteristics to those in eukaryotes, but most species have very few satellites: only 21 species in Archaea and 18 in Bacteria have more than 4 satellites/Mb. The distribution of satellites in these species is reminiscent of what is found in eukaryotes, but we find two significant differences: most satellites have a short length and many of them correspond to segments of genes coding for amino acid repeats. Transposition of non-coding satellites throughout the genome occurs rarely: only in the bacteria Leptospira interrogans and the archaea Methanocella conradii we have detected satellite families of transposed satellites with long repeats. Conclusions Our results demonstrate that the presence of satellites in the genome is not an exclusive feature of eukaryotes. We have described a few prokaryotes which do contain satellites. We present a discussion on their eventual evolutionary significance. Electronic supplementary material The online version of this article (10.1186/s12862-019-1504-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Juan A Subirana
- Department of Computer Science, Universitat Politècnica de Catalunya, Jordi Girona 1-3, 08034, Barcelona, Spain.
| | - Xavier Messeguer
- Department of Computer Science, Universitat Politècnica de Catalunya, Jordi Girona 1-3, 08034, Barcelona, Spain
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30
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Falcão MVD, Silveira PPM, Santana VLA, da Rocha LO, Chaves KP, Mota RA. First record of Burkholderia mallei Turkey 10 strain originating from glanderous horses from Brazil. Braz J Microbiol 2019; 50:1125-1127. [PMID: 31321739 DOI: 10.1007/s42770-019-00113-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 06/25/2019] [Indexed: 11/30/2022] Open
Abstract
Burkholderia (B.) mallei is the causative agent of glanders in Equidae. This study describes the first record of the Turkey 10 strain of B. mallei in glanderous horses in Northeastern of Brazil. This description should contribute to the future actions of diagnosis, control, and eradication of this disease in Brazil.
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Affiliation(s)
- Marcus Vinícius D Falcão
- Department of Veterinary Medicine, Laboratory of Infectious Diseases of Domestic Animals, Federal Rural University of Pernambuco, Manoel de Medeiros street, w/n, Dois Irmãos, Recife, PE, CEP: 52171-900, Brazil.
| | - Pedro P M Silveira
- Federal Superintendence of Agriculture, Livestock and Supply in the State of Pernambuco, Ministry of Agriculture, Livestock and Supply, General San Martin Avenue, 1000, Bongi, Recife, PE, CEP: 50630-060, Brazil
| | - Vania L A Santana
- Federal Superintendence of Agriculture, Livestock and Supply in the State of Pernambuco, Ministry of Agriculture, Livestock and Supply, General San Martin Avenue, 1000, Bongi, Recife, PE, CEP: 50630-060, Brazil
| | - Larissa O da Rocha
- Academic Unit of Viçosa, Laboratory of Infectious Diseases of Domestic Animals, Federal University of Alagoas, Manoel Severino Barbosa, w/n, Bom Sucesso, Viçosa, AL, CEP: 57309-005, Brazil
| | - Karla P Chaves
- Academic Unit of Viçosa, Laboratory of Infectious Diseases of Domestic Animals, Federal University of Alagoas, Manoel Severino Barbosa, w/n, Bom Sucesso, Viçosa, AL, CEP: 57309-005, Brazil
| | - Rinaldo A Mota
- Department of Veterinary Medicine, Laboratory of Infectious Diseases of Domestic Animals, Federal Rural University of Pernambuco, Manoel de Medeiros street, w/n, Dois Irmãos, Recife, PE, CEP: 52171-900, Brazil
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DeShazer D. A novel contact-independent T6SS that maintains redox homeostasis via Zn 2+ and Mn 2+ acquisition is conserved in the Burkholderia pseudomallei complex. Microbiol Res 2019; 226:48-54. [PMID: 31284944 DOI: 10.1016/j.micres.2019.05.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/08/2019] [Accepted: 05/30/2019] [Indexed: 12/21/2022]
Abstract
The Burkholderia pseudomallei complex consists of six phylogenetically related Gram-negative bacterial species that include environmental saprophytes and mammalian pathogens. These microbes possess multiple type VI secretion systems (T6SS) that provide a fitness advantage in diverse niches by translocating effector molecules into prokaryotic and eukaryotic cells in a contact-dependent manner. Several recent studies have elucidated the regulation and function of T6SS-2, a novel contact-independent member of the T6SS family. Expression of the T6SS-2 gene cluster is repressed by OxyR, Zur and TctR and is activated by GvmR and reactive oxygen species (ROS). The last two genes of the T6SS-2 gene cluster encode a zincophore (TseZ) and a manganeseophore (TseM) that are exported into the extracellular milieu in a contact-independent fashion when microbes encounter oxidative stress. TseZ and TseM bind Zn2+ and Mn2+, respectively, and deliver them to bacteria where they provide protection against the lethal effects of ROS. The TonB-dependent transporters that interact with TseZ and TseM, and actively transport Zn2+ and Mn2+ across the outer membrane, have also been identified. Finally, T6SS-2 provides a contact-independent growth advantage in nutrient limited environments and is critical for virulence in Galleria mellonella larvae, but is dispensable for virulence in rodent models of infection.
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Affiliation(s)
- David DeShazer
- Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA.
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Lafontaine ER, Chen Z, Huertas-Diaz MC, Dyke JS, Jelesijevic TP, Michel F, Hogan RJ, He B. The autotransporter protein BatA is a protective antigen against lethal aerosol infection with Burkholderia mallei and Burkholderia pseudomallei. Vaccine X 2019; 1:100002. [PMID: 33826684 PMCID: PMC6668238 DOI: 10.1016/j.jvacx.2018.100002] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 08/06/2018] [Accepted: 12/07/2018] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Burkholderia mallei and Burkholderia pseudomallei are the causative agents of glanders and melioidosis, respectively. There is no vaccine to protect against these highly-pathogenic and intrinsically antibiotic-resistant bacteria, and there is concern regarding their use as biological warfare agents. For these reasons, B. mallei and B. pseudomallei are classified as Tier 1 organisms by the U.S. Federal Select Agent Program and the availability of effective countermeasures represents a critical unmet need. METHODS Vaccines (subunit and vectored) containing the surface-exposed passenger domain of the conserved Burkholderia autotransporter protein BatA were administered to BALB/c mice and the vaccinated animals were challenged with lethal doses of wild-type B. mallei and B. pseudomallei strains via the aerosol route. Mice were monitored for signs of illness for a period of up to 40 days post-challenge and tissues from surviving animals were analyzed for bacterial burden at study end-points. RESULTS A single dose of recombinant Parainfluenza Virus 5 (PIV5) expressing BatA provided 74% and 60% survival in mice infected with B. mallei and B. pseudomallei, respectively. Vaccination with PIV5-BatA also resulted in complete bacterial clearance from the lungs and spleen of 78% and 44% of animals surviving lethal challenge with B. pseudomallei, respectively. In contrast, all control animals vaccinated with a PIV5 construct expressing an irrelevant antigen and infected with B. pseudomallei were colonized in those tissues. CONCLUSION Our study indicates that the autotransporter BatA is a valuable target for developing countermeasures against B. mallei and B. pseudomallei and demonstrates the utility of the PIV5 viral vaccine delivery platform to elicit cross-protective immunity against the organisms.
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Affiliation(s)
- Eric R. Lafontaine
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
| | - Zhenhai Chen
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
| | - Maria Cristina Huertas-Diaz
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
| | - Jeremy S. Dyke
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
| | - Tomislav P. Jelesijevic
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
| | - Frank Michel
- Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
| | - Robert J. Hogan
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
- Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
| | - Biao He
- Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA 30602, USA
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DeShazer D, Lovett S, Richardson J, Koroleva G, Kuehl K, Amemiya K, Sun M, Worsham P, Welkos S. Bacteriophage-associated genes responsible for the widely divergent phenotypes of variants of Burkholderia pseudomallei strain MSHR5848. J Med Microbiol 2019; 68:263-278. [PMID: 30628877 DOI: 10.1099/jmm.0.000908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
PURPOSE Burkholderia pseudomallei, the tier 1 agent of melioidosis, is a saprophytic microbe that causes endemic infections in tropical regions such as South-East Asia and Northern Australia. It is globally distributed, challenging to diagnose and treat, infectious by several routes including inhalation, and has potential for adversarial use. B. pseudomallei strain MSHR5848 produces two colony variants, smooth (S) and rough (R), which exhibit a divergent range of morphological, biochemical and metabolic phenotypes, and differ in macrophage and animal infectivity. We aimed to characterize two major phenotypic differences, analyse gene expression and study the regulatory basis of the variation. METHODOLOGY Phenotypic expression was characterized by DNA and RNA sequencing, microscopy, and differential bacteriology. Regulatory genes were identified by cloning and bioinformatics.Results/Key findings. Whereas S produced larger quantities of extracellular DNA, R was upregulated in the production of a unique chromosome 1-encoded Siphoviridae-like bacteriophage, φMSHR5848. Exploratory transcriptional analyses revealed significant differences in variant expression of genes encoding siderophores, pili assembly, type VI secretion system cluster 4 (T6SS-4) proteins, several exopolysaccharides and secondary metabolites. A single 3 base duplication in S was the only difference that separated the variants genetically. It occurred upstream of a cluster of bacteriophage-associated genes on chromosome 2 that were upregulated in S. The first two genes were involved in regulating expression of the multiple phenotypes distinguishing S and R. CONCLUSION Bacteriophage-associated proteins have a major role in the phenotypic expression of MSHR5848. The goals are to determine the regulatory basis of this phenotypic variation and its role in pathogenesis and environmental persistence of B. pseudomallei.
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Affiliation(s)
- David DeShazer
- 1Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - Sean Lovett
- 2Center for Genome Sciences, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - Joshua Richardson
- 2Center for Genome Sciences, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - Galina Koroleva
- 2Center for Genome Sciences, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA.,†Present address: Room 7N109, Center for Human Immunology, Autoimmunity and Inflammation, National Institute of Allergy and Infectious Diseases, 10 Center Drive, Bethesda, MD 20814, USA
| | - Kathleen Kuehl
- 3Pathology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - Kei Amemiya
- 1Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - Mei Sun
- 4United States Army Medical Research and Materiel Command (USAMRMC), Frederick, MD, USA
| | - Patricia Worsham
- 1Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
| | - Susan Welkos
- 1Bacteriology Division, United States Army Medical Research Institute of Infectious Diseases (USAMRIID), Frederick, MD, USA
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Hogan RJ, Lafontaine ER. Antibodies Are Major Drivers of Protection against Lethal Aerosol Infection with Highly Pathogenic Burkholderia spp. mSphere 2019; 4:e00674-18. [PMID: 30602525 PMCID: PMC6315082 DOI: 10.1128/msphere.00674-18] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Burkholderia pseudomallei and Burkholderia mallei are the causative agents of melioidosis and glanders, respectively. There is no vaccine to protect against these highly pathogenic bacteria, and there is concern regarding their emergence as global public health (B. pseudomallei) and biosecurity (B. mallei) threats. In this issue of mSphere, an article by Khakhum and colleagues (N. Khakhum, P. Bharaj, J. N. Myers, D. Tapia, et al., mSphere 4:e00570-18, 2019, https://doi.org/10.1128/mSphere.00570-18) describes a novel vaccination platform with excellent potential for cross-protection against both Burkholderia species. The report also highlights the importance of antibodies in immunity against these facultative intracellular organisms.
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Affiliation(s)
- Robert J Hogan
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
- Department of Veterinary Biosciences and Diagnostic Imaging, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
| | - Eric R Lafontaine
- Department of Infectious Diseases, College of Veterinary Medicine, University of Georgia, Athens, Georgia, USA
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Mannaa M, Park I, Seo YS. Genomic Features and Insights into the Taxonomy, Virulence, and Benevolence of Plant-Associated Burkholderia Species. Int J Mol Sci 2018; 20:E121. [PMID: 30598000 PMCID: PMC6337347 DOI: 10.3390/ijms20010121] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Revised: 12/24/2018] [Accepted: 12/24/2018] [Indexed: 11/17/2022] Open
Abstract
The members of the Burkholderia genus are characterized by high versatility and adaptability to various ecological niches. With the availability of the genome sequences of numerous species of Burkholderia, many studies have been conducted to elucidate the unique features of this exceptional group of bacteria. Genomic and metabolic plasticity are common among Burkholderia species, as evidenced by their relatively large multi-replicon genomes that are rich in insertion sequences and genomic islands and contain a high proportion of coding regions. Such unique features could explain their adaptability to various habitats and their versatile lifestyles, which are reflected in a multiplicity of species including free-living rhizospheric bacteria, plant endosymbionts, legume nodulators, and plant pathogens. The phytopathogenic Burkholderia group encompasses several pathogens representing threats to important agriculture crops such as rice. Contrarily, plant-beneficial Burkholderia have also been reported, which have symbiotic and growth-promoting roles. In this review, the taxonomy of Burkholderia is discussed emphasizing the recent updates and the contributions of genomic studies to precise taxonomic positioning. Moreover, genomic and functional studies on Burkholderia are reviewed and insights are provided into the mechanisms underlying the virulence and benevolence of phytopathogenic and plant-beneficial Burkholderia, respectively, on the basis of cutting-edge knowledge.
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Affiliation(s)
- Mohamed Mannaa
- Department of Integrated Biological Science, Pusan National University, Busan 46241, Korea.
| | - Inmyoung Park
- Department of Oriental Food and Culinary Arts, Youngsan University, Busan 48015, Korea.
| | - Young-Su Seo
- Department of Integrated Biological Science, Pusan National University, Busan 46241, Korea.
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Bochkareva OO, Moroz EV, Davydov II, Gelfand MS. Genome rearrangements and selection in multi-chromosome bacteria Burkholderia spp. BMC Genomics 2018; 19:965. [PMID: 30587126 PMCID: PMC6307245 DOI: 10.1186/s12864-018-5245-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 11/14/2018] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND The genus Burkholderia consists of species that occupy remarkably diverse ecological niches. Its best known members are important pathogens, B. mallei and B. pseudomallei, which cause glanders and melioidosis, respectively. Burkholderia genomes are unusual due to their multichromosomal organization, generally comprised of 2-3 chromosomes. RESULTS We performed integrated genomic analysis of 127 Burkholderia strains. The pan-genome is open with the saturation to be reached between 86,000 and 88,000 genes. The reconstructed rearrangements indicate a strong avoidance of intra-replichore inversions that is likely caused by selection against the transfer of large groups of genes between the leading and the lagging strands. Translocated genes also tend to retain their position in the leading or the lagging strand, and this selection is stronger for large syntenies. Integrated reconstruction of chromosome rearrangements in the context of strains phylogeny reveals parallel rearrangements that may indicate inversion-based phase variation and integration of new genomic islands. In particular, we detected parallel inversions in the second chromosomes of B. pseudomallei with breakpoints formed by genes encoding membrane components of multidrug resistance complex, that may be linked to a phase variation mechanism. Two genomic islands, spreading horizontally between chromosomes, were detected in the B. cepacia group. CONCLUSIONS This study demonstrates the power of integrated analysis of pan-genomes, chromosome rearrangements, and selection regimes. Non-random inversion patterns indicate selective pressure, inversions are particularly frequent in a recent pathogen B. mallei, and, together with periods of positive selection at other branches, may indicate adaptation to new niches. One such adaptation could be a possible phase variation mechanism in B. pseudomallei.
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Affiliation(s)
- Olga O. Bochkareva
- Kharkevich Institute for Information Transmission Problems, Moscow, Russia
- Center of Life Sciences Skolkovo Institute of Science and Technology, Moscow, Russia
| | - Elena V. Moroz
- Kharkevich Institute for Information Transmission Problems, Moscow, Russia
| | - Iakov I. Davydov
- Department of Ecology and Evolution & Department of Computational Biology, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Mikhail S. Gelfand
- Kharkevich Institute for Information Transmission Problems, Moscow, Russia
- Center of Life Sciences Skolkovo Institute of Science and Technology, Moscow, Russia
- Faculty of Computer Science, Higher School of Economics, Moscow, Russia
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MarR Family Transcription Factors from Burkholderia Species: Hidden Clues to Control of Virulence-Associated Genes. Microbiol Mol Biol Rev 2018; 83:83/1/e00039-18. [PMID: 30487164 DOI: 10.1128/mmbr.00039-18] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Species within the genus Burkholderia exhibit remarkable phenotypic diversity. Genomic plasticity, including genome reduction and horizontal gene transfer, has been correlated with virulence traits in several species. However, the conservation of virulence genes in species otherwise considered to have limited potential for infection suggests that phenotypic diversity may not be explained solely on the basis of genetic diversity. Instead, differential organization and control of gene regulatory networks may underlie many phenotypic differences. In this review, we evaluate how regulation of gene expression by members of the multiple antibiotic resistance regulator (MarR) family of transcription factors may contribute to shaping the physiological diversity of Burkholderia species, with a focus on the clinically relevant human pathogens. All Burkholderia species encode a relatively large number of MarR proteins, a feature common to bacteria that must respond to environmental changes such as those associated with host invasion. However, evolution of gene regulatory networks has likely resulted in orthologous transcription factors controlling disparate sets of genes. Adaptation to, and survival in, diverse habitats, including a human or plant host, is key to the success of Burkholderia species as (opportunistic) pathogens, and recent reports suggest that control of virulence-associated genes by MarR proteins features prominently among the survival strategies employed by these species. We suggest that identification of MarR regulons will contribute significantly to clarification of virulence determinants and phenotypic diversity.
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Misra HS, Maurya GK, Kota S, Charaka VK. Maintenance of multipartite genome system and its functional significance in bacteria. J Genet 2018; 97:1013-1038. [PMID: 30262715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Bacteria are unicellular organisms that do not show compartmentalization of the genetic material and other cellular organelles as seen in higher organisms. Earlier, bacterial genomes were defined as single circular chromosome and extrachromosomal plasmids. Recently, many bacteria were found harbouringmultipartite genome system and the numbers of copies of genome elements including chromosomes vary from one to several per cell. Interestingly, it is noticed that majority of multipartite genome-harbouring bacteria are either stress tolerant or pathogens. Further, it is observed that the secondary genomes in these bacteria encode proteins that are involved in bacterial genome maintenance and also contribute to higher stress tolerance, and pathogenicity in pathogenic bacteria. Surprisingly, in some bacteria the genes encoding the proteins of classical homologous recombination pathways are present only on the secondary chromosomes, and some do not have either of the classical homologous recombination pathways. This review highlights the presence of ploidy and multipartite genomes in bacterial system, the underlying mechanisms of genome maintenance and the possibilities of these features contributing to higher abiotic and biotic stress tolerance in these bacteria.
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Affiliation(s)
- Hari Sharan Misra
- Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 085, India.
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Rossi E, Paroni M, Landini P. Biofilm and motility in response to environmental and host-related signals in Gram negative opportunistic pathogens. J Appl Microbiol 2018; 125:1587-1602. [PMID: 30153375 DOI: 10.1111/jam.14089] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 05/30/2018] [Accepted: 07/20/2018] [Indexed: 12/13/2022]
Abstract
Most bacteria can switch between a planktonic, sometimes motile, form and a biofilm mode, in which bacterial cells can aggregate and attach to a solid surface. The transition between these two forms represents an example of bacterial adaptation to environmental signals and stresses. In 'environmental pathogens', namely, environmental bacteria that are also able to cause disease in animals and humans, signals associated either with the host or with the external environment, such as temperature, oxygen availability, nutrient concentrations etc., play a major role in triggering the switch between the motile and the biofilm mode, via complex regulatory mechanisms that control flagellar synthesis and motility, and production of adhesion factors. In this review article, we present examples of how environmental signals can impact biofilm formation and cell motility in the Gram negative bacteria Pseudomonas aeruginosa, Escherichia coli and in the Burkholderia genus, and how the switch between motile and biofilm mode can be an essential part of a more general process of adaptation either to the host or to the external environment.
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Affiliation(s)
- E Rossi
- Department of Clinical Microbiology, Rigshospitalet, København, Denmark
| | - M Paroni
- Department of Biosciences, Università degli Studi di Milano, Milan, Italy
| | - P Landini
- Department of Biosciences, Università degli Studi di Milano, Milan, Italy
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Misra HS, Maurya GK, Kota S, Charaka VK. Maintenance of multipartite genome system and its functional significance in bacteria. J Genet 2018. [DOI: 10.1007/s12041-018-0969-x] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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41
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Sadiq MA, Hassan L, Aziz SA, Zakaria Z, Musa HI, Amin MM, Othman N. Phylogenetic Diversity of Burkholderia pseudomallei isolated from veterinary cases and the environments in Peninsular Malaysia. Vet Anim Sci 2018; 6:21-28. [PMID: 32734049 PMCID: PMC7386693 DOI: 10.1016/j.vas.2018.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2017] [Accepted: 07/30/2018] [Indexed: 12/01/2022] Open
Abstract
This study was designed to determine the genotype and the phylogeny of Burkholderia pseudomallei isolated from veterinary cases and from the animal environments in Peninsular Malaysia. The Malaysian B. pseudomallei population were then compared to those found elsewhere. A total of 113 isolates from veterinary cases (35) and the environment (56 from soil and 22 from water) were characterized using multilocus sequence typing (MLST). Two novel alleles, allele 97 and 69 of the gene locus ace and lepA respectively were recovered. Isolates were resolved into 12 distinct sequence types (STs) out of which five were novel, namely ST1130, ST1131, ST1338, ST1339 and ST1367. The isolates from veterinary cases co-clustered with those from the environment. B. pseudomallei isolates in this study were highly clonal and have descended from a common ancestor clonal complex (CC) 48 found in Southeast Asia. This study shows that veterinary case isolates are often caused by similar STs, with similar populations found in the direct animal environment and those previously reported to cause human infections in Malaysia and elsewhere. Isolates of B. pseudomallei from human infections have been given more attention, with a comparatively lower focus on isolates from animals and the farm environment. This study highlighted the genotype and phylogeny of B. pseudomallei isolated from animals and the environment and their relations to the isolates from human cases reported in Malaysia and elsewhere. Most STs reported in this study, from veterinary cases and animal environment are similar to those previously reported as causing human infections in Malaysia and elsewhere. Therefore, even though direct zoonosis is uncommon, monitoring melioidosis occurrences in animals can provide insights on the bacterial strains infecting humans.
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Affiliation(s)
- Muhammad Abubakar Sadiq
- Faculty of Veterinary Medicine, Universiti Putra Malaysia (UPM), 44300 UPM Serdang, Selangor Darul Ehsan, Malaysia.,Department of Veterinary Public Health and Preventive Medicine, Faculty of Veterinary Medicine, University of Maiduguri, P.M.B 1069, Maiduguri, Borno State, Nigeria
| | - Latiffah Hassan
- Faculty of Veterinary Medicine, Universiti Putra Malaysia (UPM), 44300 UPM Serdang, Selangor Darul Ehsan, Malaysia
| | - Saleha Abdul Aziz
- Faculty of Veterinary Medicine, Universiti Putra Malaysia (UPM), 44300 UPM Serdang, Selangor Darul Ehsan, Malaysia
| | - Zunita Zakaria
- Faculty of Veterinary Medicine, Universiti Putra Malaysia (UPM), 44300 UPM Serdang, Selangor Darul Ehsan, Malaysia
| | - Hassan Ismail Musa
- Faculty of Veterinary Medicine, Universiti Putra Malaysia (UPM), 44300 UPM Serdang, Selangor Darul Ehsan, Malaysia.,Department of Veterinary Public Health and Preventive Medicine, Faculty of Veterinary Medicine, University of Maiduguri, P.M.B 1069, Maiduguri, Borno State, Nigeria
| | - Maswati Mat Amin
- Makmal Veterinar Kawasan Bukit Tengah, Peti Surat 63, 14007 Bukit Mertajam, Seberang Perai Tengah, Pulau Pinang, Malaysia
| | - Norlida Othman
- Makmal Veterinar Kawasan Kota Bharu, Jabatan Perkhidmatan Veterinar 16150 Kubang Kerian, Kota Bharu, Kelantan, Malaysia
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Loong SK, Soh YH, Mahfodz NH, Johari J, AbuBakar S. Synovial Tissue Infection with Burkholderia fungorum. Emerg Infect Dis 2018; 22:1834-5. [PMID: 27648477 PMCID: PMC5038425 DOI: 10.3201/eid2210.151114] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Klonowska A, Melkonian R, Miché L, Tisseyre P, Moulin L. Transcriptomic profiling of Burkholderia phymatum STM815, Cupriavidus taiwanensis LMG19424 and Rhizobium mesoamericanum STM3625 in response to Mimosa pudica root exudates illuminates the molecular basis of their nodulation competitiveness and symbiotic evolutionary history. BMC Genomics 2018; 19:105. [PMID: 29378510 PMCID: PMC5789663 DOI: 10.1186/s12864-018-4487-2] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2017] [Accepted: 01/17/2018] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND Rhizobial symbionts belong to the classes Alphaproteobacteria and Betaproteobacteria (called "alpha" and "beta"-rhizobia). Most knowledge on the genetic basis of symbiosis is based on model strains belonging to alpha-rhizobia. Mimosa pudica is a legume that offers an excellent opportunity to study the adaptation toward symbiotic nitrogen fixation in beta-rhizobia compared to alpha-rhizobia. In a previous study (Melkonian et al., Environ Microbiol 16:2099-111, 2014) we described the symbiotic competitiveness of M. pudica symbionts belonging to Burkholderia, Cupriavidus and Rhizobium species. RESULTS In this article we present a comparative analysis of the transcriptomes (by RNAseq) of B. phymatum STM815 (BP), C. taiwanensis LMG19424 (CT) and R. mesoamericanum STM3625 (RM) in conditions mimicking the early steps of symbiosis (i.e. perception of root exudates). BP exhibited the strongest transcriptome shift both quantitatively and qualitatively, which mirrors its high competitiveness in the early steps of symbiosis and its ancient evolutionary history as a symbiont, while CT had a minimal response which correlates with its status as a younger symbiont (probably via acquisition of symbiotic genes from a Burkholderia ancestor) and RM had a typical response of Alphaproteobacterial rhizospheric bacteria. Interestingly, the upregulation of nodulation genes was the only common response among the three strains; the exception was an up-regulated gene encoding a putative fatty acid hydroxylase, which appears to be a novel symbiotic gene specific to Mimosa symbionts. CONCLUSION The transcriptional response to root exudates was correlated to each strain nodulation competitiveness, with Burkholderia phymatum appearing as the best specialised symbiont of Mimosa pudica.
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Affiliation(s)
| | - Rémy Melkonian
- IRD, UMR LSTM, Campus de Baillarguet, Montpellier, France
| | - Lucie Miché
- IRD, UMR LSTM, Campus de Baillarguet, Montpellier, France.,Present address: Aix Marseille University, University of Avignon, CNRS, IRD, IMBE, Marseille, France
| | | | - Lionel Moulin
- IRD, Cirad, University of Montpellier, IPME, Montpellier, France.
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Norris MH, Khan MSR, Chirakul S, Schweizer HP, Tuanyok A. Outer Membrane Vesicle Vaccines from Biosafe Surrogates Prevent Acute Lethal Glanders in Mice. Vaccines (Basel) 2018; 6:E5. [PMID: 29320408 PMCID: PMC5874646 DOI: 10.3390/vaccines6010005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 01/04/2018] [Accepted: 01/06/2018] [Indexed: 01/13/2023] Open
Abstract
Burkholderia mallei is a host-adapted Gram-negative mammalian pathogen that causes the severe disease glanders. Glanders can manifest as a rapid acute progression or a chronic debilitating syndrome primarily affecting solipeds and humans in close association with infected animals. In USA, B. mallei is classified as one of the most important bacterial biothreat agents. Presently, there is no licensed glanders vaccine available for humans or animals. In this work, outer membrane vesicles (OMVs) were isolated from three attenuated biosafe bacterial strains, Burkholderia pseudomallei Bp82, B. thailandensis E555, and B. thailandensis TxDOH and used to vaccinate mice. B. thailandensis OMVs induced significantly higher antibody responses that were investigated. B. mallei specific serum antibody responses were of higher magnitude in mice vaccinated with B. thailandensis OMVs compared to levels in mice vaccinated with B. pseudomallei OMVs. OMVs derived from biosafe strains protected mice from acute lethal glanders with vesicles from the two B. thailandensis strains affording significant protection (>90%) up to 35 days post-infection with some up to 60 days. Organ loads from 35-day survivors indicated bacteria colonization of the lungs, liver, and spleen while those from 60 days had high CFUs in the spleens. The highest antibody producing vaccine (B. thailandensis E555 OMVs) also protected C57BL/6 mice from acute inhalational glanders with evidence of full protection.
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Affiliation(s)
- Michael H Norris
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine; University of Florida, Gainesville, FL 32608, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
| | - Mohammad S R Khan
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine; University of Florida, Gainesville, FL 32608, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
| | - Sunisa Chirakul
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine; University of Florida, Gainesville, FL 32608, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
| | - Herbert P Schweizer
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
- Department of Molecular Genetics and Microbiology, College of Medicine, University of Florida, Gainesville, FL 32603, USA.
| | - Apichai Tuanyok
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine; University of Florida, Gainesville, FL 32608, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA.
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Zimmerman SM, Long ME, Dyke JS, Jelesijevic TP, Michel F, Lafontaine ER, Hogan RJ. Use of Immunohistochemistry to Demonstrate In Vivo Expression of the Burkholderia mallei Virulence Factor BpaB During Experimental Glanders. Vet Pathol 2017; 55:258-267. [PMID: 29145795 DOI: 10.1177/0300985817736113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Burkholderia mallei causes the highly contagious and debilitating zoonosis glanders, which infects via inhalation or percutaneous inoculation and often culminates in life-threatening pneumonia and sepsis. In humans, glanders is difficult to diagnose and requires prolonged antibiotic therapy with low success rates. No vaccine exists to protect against B. mallei, and there is concern regarding its use as a bioweapon. The authors previously identified the protein BpaB as a potential target for devising therapies due to its role in adherence to host cells and the formation of biofilms in vitro and its contribution to pathogenicity in a mouse model of glanders. In the present study, the authors developed an immunostaining approach to probe tissues of experimentally infected animals and demonstrated that BpaB is produced exclusively in vivo by wild-type B. mallei in target organs from mice and marmosets. They detected the expression of BpaB by B. mallei both extracellularly and within macrophages, neutrophils, and epithelial cells in respiratory tissues (7/10 marmoset; 2/2 mouse). The authors also noted the intracellular expression of BpaB by B. mallei in macrophages in the regional lymph nodes of mice (2/2 tissues) and MALT of marmosets (4/5 tissues). It is interesting that B. mallei bacteria infecting distal organs did not express BpaB (2/2 mice; 3/3 marmosets), suggesting that the protein is not necessary for bacterial fitness in these anatomic locations. These findings underscore the value of BpaB as a target for developing medical countermeasures and provide insight into its role in pathogenesis.
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Affiliation(s)
- Shawn M Zimmerman
- 1 Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | - Mackenzie E Long
- 2 Veterinary Teaching Hospital, University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | - Jeremy S Dyke
- 1 Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | - Tomislav P Jelesijevic
- 1 Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | - Frank Michel
- 3 Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | - Eric R Lafontaine
- 1 Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | - Robert J Hogan
- 1 Department of Infectious Diseases, University of Georgia College of Veterinary Medicine, Athens, GA, USA.,3 Department of Veterinary Biosciences and Diagnostic Imaging, University of Georgia College of Veterinary Medicine, Athens, GA, USA
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Butt AT, Thomas MS. Iron Acquisition Mechanisms and Their Role in the Virulence of Burkholderia Species. Front Cell Infect Microbiol 2017; 7:460. [PMID: 29164069 PMCID: PMC5681537 DOI: 10.3389/fcimb.2017.00460] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Accepted: 10/18/2017] [Indexed: 11/19/2022] Open
Abstract
Burkholderia is a genus within the β-Proteobacteriaceae that contains at least 90 validly named species which can be found in a diverse range of environments. A number of pathogenic species occur within the genus. These include Burkholderia cenocepacia and Burkholderia multivorans, opportunistic pathogens that can infect the lungs of patients with cystic fibrosis, and are members of the Burkholderia cepacia complex (Bcc). Burkholderia pseudomallei is also an opportunistic pathogen, but in contrast to Bcc species it causes the tropical human disease melioidosis, while its close relative Burkholderia mallei is the causative agent of glanders in horses. For these pathogens to survive within a host and cause disease they must be able to acquire iron. This chemical element is essential for nearly all living organisms due to its important role in many enzymes and metabolic processes. In the mammalian host, the amount of accessible free iron is negligible due to the low solubility of the metal ion in its higher oxidation state and the tight binding of this element by host proteins such as ferritin and lactoferrin. As with other pathogenic bacteria, Burkholderia species have evolved an array of iron acquisition mechanisms with which to capture iron from the host environment. These mechanisms include the production and utilization of siderophores and the possession of a haem uptake system. Here, we summarize the known mechanisms of iron acquisition in pathogenic Burkholderia species and discuss the evidence for their importance in the context of virulence and the establishment of infection in the host. We have also carried out an extensive bioinformatic analysis to identify which siderophores are produced by each Burkholderia species that is pathogenic to humans.
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Affiliation(s)
- Aaron T Butt
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, United Kingdom
| | - Mark S Thomas
- Department of Infection, Immunity and Cardiovascular Disease, Faculty of Medicine, Dentistry and Health, University of Sheffield, Sheffield, United Kingdom
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Titball RW, Burtnick MN, Bancroft GJ, Brett P. Burkholderia pseudomallei and Burkholderia mallei vaccines: Are we close to clinical trials? Vaccine 2017; 35:5981-5989. [DOI: 10.1016/j.vaccine.2017.03.022] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/17/2017] [Accepted: 03/07/2017] [Indexed: 10/19/2022]
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Antibodies against In Vivo-Expressed Antigens Are Sufficient To Protect against Lethal Aerosol Infection with Burkholderia mallei and Burkholderia pseudomallei. Infect Immun 2017; 85:IAI.00102-17. [PMID: 28507073 DOI: 10.1128/iai.00102-17] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2017] [Accepted: 05/08/2017] [Indexed: 12/22/2022] Open
Abstract
Burkholderia mallei, a facultative intracellular bacterium and tier 1 biothreat, causes the fatal zoonotic disease glanders. The organism possesses multiple genes encoding autotransporter proteins, which represent important virulence factors and targets for developing countermeasures in pathogenic Gram-negative bacteria. In the present study, we investigated one of these autotransporters, BatA, and demonstrate that it displays lipolytic activity, aids in intracellular survival, is expressed in vivo, elicits production of antibodies during infection, and contributes to pathogenicity in a mouse aerosol challenge model. A mutation in the batA gene of wild-type strain ATCC 23344 was found to be particularly attenuating, as BALB/c mice infected with the equivalent of 80 median lethal doses cleared the organism. This finding prompted us to test the hypothesis that vaccination with the batA mutant strain elicits protective immunity against subsequent infection with wild-type bacteria. We discovered that not only does vaccination provide high levels of protection against lethal aerosol challenge with B. mallei ATCC 23344, it also protects against infection with multiple isolates of the closely related organism and causative agent of melioidosis, Burkholderia pseudomallei Passive-transfer experiments also revealed that the protective immunity afforded by vaccination with the batA mutant strain is predominantly mediated by IgG antibodies binding to antigens expressed exclusively in vivo Collectively, our data demonstrate that BatA is a target for developing medical countermeasures and that vaccination with a mutant lacking expression of the protein provides a platform to gain insights regarding mechanisms of protective immunity against B. mallei and B. pseudomallei, including antigen discovery.
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Parhizgari N, Gouya MM, Mostafavi E. Emerging and re-emerging infectious diseases in Iran. IRANIAN JOURNAL OF MICROBIOLOGY 2017; 9:122-142. [PMID: 29225752 PMCID: PMC5719507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Despite development of preventive and controlling strategies regarding infectious diseases, they are still considered as one of the most significant leading causes of morbidity and mortality, worldwide. Changes in humans' demographics and behaviors, microbial and ecological alterations, agricultural development, international travels and susceptibility to infectious diseases have resulted in increased reports of emerging infectious diseases (EIDs) and reemerging infectious diseases (RIDs) in various geographical areas. Because of the various types of geographic properties in Iran, substantial climatic variability, as well as unstable political situations and poor public health conditions in some of neighboring countries, EIDs and RIDs are serious public health problems; among them, zoonotic and drug resistant diseases are the most significant. Hence, this review provides an overview of the significant bacterial, viral and fungal EIDs and RIDs in Iran regarding their epidemiological aspects.
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Affiliation(s)
- Najmeh Parhizgari
- Department of Virology, School of Public Health, Tehran University of Medical Sciences, Tehran, Iran,Department of Epidemiology and Biostatistics, Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Tehran, Iran
| | - Mohammad Mehdi Gouya
- The Center for Communicable Diseases Control, Department for Health Affairs, Ministry of Health and Medical Education, Tehran, Iran
| | - Ehsan Mostafavi
- Department of Epidemiology and Biostatistics, Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Tehran, Iran,National Reference Laboratory for Plague, Tularemia and Q Fever, Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Akanlu, Kabudar Ahang, Hamadan, Iran,Corresponding author: Ehsan Mostafavi, DVM, PhD, Department of Epidemiology and Biostatistics, Research Centre for Emerging and Reemerging Infectious Diseases, Pasteur Institute of Iran, Tehran, Iran. Telefax: +98-21-66496448,
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Vibrio cholerae VciB Mediates Iron Reduction. J Bacteriol 2017; 199:JB.00874-16. [PMID: 28348025 DOI: 10.1128/jb.00874-16] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2016] [Accepted: 03/19/2017] [Indexed: 11/20/2022] Open
Abstract
Vibrio cholerae is the causative agent of the severe diarrheal disease cholera. V. cholerae thrives within the human host, where it replicates to high numbers, but it also persists within the aquatic environments of ocean and brackish water. To survive within these nutritionally diverse environments, V. cholerae must encode the necessary tools to acquire the essential nutrient iron in all forms it may encounter. A prior study of systems involved in iron transport in V. cholerae revealed the existence of vciB, which, while unable to directly transport iron, stimulates the transport of iron through ferrous (Fe2+) iron transport systems. We demonstrate here a role for VciB in V. cholerae in which VciB stimulates the reduction of Fe3+ to Fe2+, which can be subsequently transported into the cell with the ferrous iron transporter Feo. Iron reduction is independent of functional iron transport but is associated with the electron transport chain. Comparative analysis of VciB orthologs suggests a similar role for other proteins in the VciB family. Our data indicate that VciB is a dimer located in the inner membrane with three transmembrane segments and a large periplasmic loop. Directed mutagenesis of the protein reveals two highly conserved histidine residues required for function. Taken together, our results support a model whereby VciB reduces ferric iron using energy from the electron transport chain.IMPORTANCEVibrio cholerae is a prolific human pathogen and environmental organism. The acquisition of essential nutrients such as iron is critical for replication, and V. cholerae encodes a number of mechanisms to use iron from diverse environments. Here, we describe the V. cholerae protein VciB that increases the reduction of oxidized ferric iron (Fe3+) to the ferrous form (Fe2+), thus promoting iron acquisition through ferrous iron transporters. Analysis of VciB orthologs in Burkholderia and Aeromonas spp. suggest that they have a similar activity, allowing a functional assignment for this previously uncharacterized protein family. This study builds upon our understanding of proteins known to mediate iron reduction in bacteria.
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