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diCenzo GC, Mengoni A, Perrin E. Chromids Aid Genome Expansion and Functional Diversification in the Family Burkholderiaceae. Mol Biol Evol 2019; 36:562-574. [PMID: 30608550 DOI: 10.1093/molbev/msy248] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
Multipartite genomes, containing at least two large replicons, are found in diverse bacteria; however, the advantage of this genome structure remains incompletely understood. Here, we perform comparative genomics of hundreds of finished β-proteobacterial genomes to gain insights into the role and emergence of multipartite genomes. Almost all essential secondary replicons (chromids) of the β-proteobacteria are found in the family Burkholderiaceae. These replicons arose from just two plasmid acquisition events, and they were likely stabilized early in their evolution by the presence of core genes. On average, Burkholderiaceae genera with multipartite genomes had a larger total genome size, but smaller chromosome, than genera without secondary replicons. Pangenome-level functional enrichment analyses suggested that interreplicon functional biases are partially driven by the enrichment of secondary replicons in the accessory pangenome fraction. Nevertheless, the small overlap in orthologous groups present in each replicon's pangenome indicated a clear functional separation of the replicons. Chromids appeared biased to environmental adaptation, as the functional categories enriched on chromids were also overrepresented on the chromosomes of the environmental genera (Paraburkholderia and Cupriavidus) compared with the pathogenic genera (Burkholderia and Ralstonia). Using ancestral state reconstruction, it was predicted that the rate of accumulation of modern-day genes by chromids was more rapid than the rate of gene accumulation by the chromosomes. Overall, the data are consistent with a model where the primary advantage of secondary replicons is in facilitating increased rates of gene acquisition through horizontal gene transfer, consequently resulting in replicons enriched in genes associated with adaptation to novel environments.
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Affiliation(s)
- George C diCenzo
- Department of Biology, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Alessio Mengoni
- Department of Biology, University of Florence, Sesto Fiorentino, Florence, Italy
| | - Elena Perrin
- Department of Biology, University of Florence, Sesto Fiorentino, Florence, Italy
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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: 14] [Impact Index Per Article: 2.3] [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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Peng C, Lin Y, Luo H, Gao F. A Comprehensive Overview of Online Resources to Identify and Predict Bacterial Essential Genes. Front Microbiol 2017; 8:2331. [PMID: 29230204 PMCID: PMC5711816 DOI: 10.3389/fmicb.2017.02331] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/13/2017] [Indexed: 12/15/2022] Open
Abstract
Genes critical for the survival or reproduction of an organism in certain circumstances are classified as essential genes. Essential genes play a significant role in deciphering the survival mechanism of life. They may be greatly applied to pharmaceutics and synthetic biology. The continuous progress of experimental method for essential gene identification has accelerated the accumulation of gene essentiality data which facilitates the study of essential genes in silico. In this article, we present some available online resources related to gene essentiality, including bioinformatic software tools for transposon sequencing (Tn-seq) analysis, essential gene databases and online services to predict bacterial essential genes. We review several computational approaches that have been used to predict essential genes, and summarize the features used for gene essentiality prediction. In addition, we evaluate the available online bacterial essential gene prediction servers based on the experimentally validated essential gene sets of 30 bacteria from DEG. This article is intended to be a quick reference guide for the microbiologists interested in the essential genes.
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Affiliation(s)
- Chong Peng
- Department of Physics, School of Science, Tianjin University, Tianjin, China
| | - Yan Lin
- Department of Physics, School of Science, Tianjin University, Tianjin, China
| | - Hao Luo
- Department of Physics, School of Science, Tianjin University, Tianjin, China
| | - Feng Gao
- Department of Physics, School of Science, Tianjin University, Tianjin, China
- Key Laboratory of Systems Bioengineering (Ministry of Education), Tianjin University, Tianjin, China
- SynBio Research Platform, Collaborative Innovation Center of Chemical Science and Engineering (Tianjin), Tianjin University, Tianjin, China
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Guo FB, Xiong L, Zhang KY, Dong C, Zhang FZ, Woo PCY. Identification and analysis of genomic islands in Burkholderia cenocepacia AU 1054 with emphasis on pathogenicity islands. BMC Microbiol 2017; 17:73. [PMID: 28347342 PMCID: PMC5369199 DOI: 10.1186/s12866-017-0986-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2016] [Accepted: 03/18/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Genomic islands (GIs) are genomic regions that reveal evidence of horizontal DNA transfer. They can code for many functions and may augment a bacterium's adaptation to its host or environment. GIs have been identified in strain J2315 of Burkholderia cenocepacia, whereas in strain AU 1054 there has been no published works on such regions according to our text mining and keyword search in Medline. RESULTS In this study, we identified 21 GIs in AU 1054 by combining two computational tools. Feature analyses suggested that the predictions are highly reliable and hence illustrated the advantage of joint predictions by two independent methods. Based on putative virulence factors, four GIs were further identified as pathogenicity islands (PAIs). Through experiments of gene deletion mutants in live bacteria, two putative PAIs were confirmed, and the virulence factors involved were identified as lipA and copR. The importance of the genes lipA (from PAI 1) and copR (from PAI 2) for bacterial invasion and replication indicates that they are required for the invasive properties of B. cenocepacia and may function as virulence determinants for bacterial pathogenesis and host infection. CONCLUSIONS This approach of in silico prediction of GIs and subsequent identification of potential virulence factors in the putative island regions with final validation using wet experiments could be used as an effective strategy to rapidly discover novel virulence factors in other bacterial species and strains.
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Affiliation(s)
- Feng-Biao Guo
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Key Laboratory for Neuro-information of the Ministry of Education, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Department of Microbiology, The University of Hong Kong, Hong Kong, Special Administrative Region, People's Republic of China
| | - Lifeng Xiong
- Department of Microbiology, The University of Hong Kong, Hong Kong, Special Administrative Region, People's Republic of China
| | - Kai-Yue Zhang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Key Laboratory for Neuro-information of the Ministry of Education, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Chuan Dong
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Key Laboratory for Neuro-information of the Ministry of Education, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Fa-Zhan Zhang
- School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Center for Informational Biology, University of Electronic Science and Technology of China, Chengdu, 610054, China.,Key Laboratory for Neuro-information of the Ministry of Education, University of Electronic Science and Technology of China, Chengdu, 610054, China
| | - Patrick C Y Woo
- Department of Microbiology, The University of Hong Kong, Hong Kong, Special Administrative Region, People's Republic of China.
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Patel S. Drivers of bacterial genomes plasticity and roles they play in pathogen virulence, persistence and drug resistance. INFECTION GENETICS AND EVOLUTION 2016; 45:151-164. [DOI: 10.1016/j.meegid.2016.08.030] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2016] [Revised: 08/26/2016] [Accepted: 08/27/2016] [Indexed: 12/11/2022]
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Abstract
Essential genes are those genes indispensable for the survival of any living cell. Bacterial essential genes constitute the cornerstones of synthetic biology and are often attractive targets in the development of antibiotics and vaccines. Because identification of essential genes with wet-lab ways often means expensive economic costs and tremendous labor, scientists changed to seek for alternative way of computational prediction. Aiming to help to solve this issue, our research group (CEFG: group of Computational, Comparative, Evolutionary and Functional Genomics, http://cefg.uestc.edu.cn) has constructed three online services to predict essential genes in bacterial genomes. These freely available tools are applicable for single gene sequences without annotated functions, single genes with definite names, and complete genomes of bacterial strains. To ensure reliable predictions, the investigated species should belong to the same family (for EGP) or phylum (for CEG_Match and Geptop) with one of the reference species, respectively. As the pilot software for the issue, predicting accuracies of them have been assessed and compared with existing algorithms, and note that all of other published algorithms have not any formed online services. We hope these services at CEFG will help scientists and researchers in the field of essential genes.
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Ye YN, Hua ZG, Huang J, Rao N, Guo FB. CEG: a database of essential gene clusters. BMC Genomics 2013; 14:769. [PMID: 24209780 PMCID: PMC4046693 DOI: 10.1186/1471-2164-14-769] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Accepted: 11/05/2013] [Indexed: 11/30/2022] Open
Abstract
Background Essential genes are indispensable for the survival of living entities. They are the cornerstones of synthetic biology, and are potential candidate targets for antimicrobial and vaccine design. Description Here we describe the Cluster of Essential Genes (CEG) database, which contains clusters of orthologous essential genes. Based on the size of a cluster, users can easily decide whether an essential gene is conserved in multiple bacterial species or is species-specific. It contains the similarity value of every essential gene cluster against human proteins or genes. The CEG_Match tool is based on the CEG database, and was developed for prediction of essential genes according to function. The database is available at http://cefg.uestc.edu.cn/ceg. Conclusions Properties contained in the CEG database, such as cluster size, and the similarity of essential gene clusters against human proteins or genes, are very important for evolutionary research and drug design. An advantage of CEG is that it clusters essential genes based on function, and therefore decreases false positive results when predicting essential genes in comparison with using the similarity alignment method. Electronic supplementary material The online version of this article (doi:10.1186/1471-2164-14-769) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | | | | | | | - Feng-Biao Guo
- Center of Bioinformatics and Key Laboratory for NeuroInformation of Ministry of Education, School of Life Science and Technology, University of Electronic Science and Technology of China, Chengdu 610054, China.
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Abstract
It has become clear that different genome regions need not evolve uniformly. This variation is particularly evident in bacterial genomes with multiple chromosomes, in which smaller, secondary chromosomes evolve more rapidly. We previously demonstrated that substitution rates and gene dispensability were greater on secondary chromosomes in many bacterial genomes. In Vibrio, the secondary chromosome is replicated later during the cell cycle, which reduces the effective dosage of these genes and hence their expression. More rapid evolution of secondary chromosomes may therefore reflect weaker purifying selection on less expressed genes. Here, we test this hypothesis by relating substitution rates of orthologs shared by multiple Burkholderia genomes, each with three chromosomes, to a study of gene expression in genomes differing by a major reciprocal translocation. This model predicts that expression should be greatest on chromosome 1 (the largest) and least on chromosome 3 (the smallest) and that expression should tend to decline within chromosomes from replication origin to terminus. Moreover, gene movement to the primary chromosome should associate with increased expression, and movement to secondary chromosomes should result in reduced expression. Our analysis supports each of these predictions, as translocated genes tended to shift expression toward their new chromosome neighbors despite inevitable cis-acting regulation of expression. This study sheds light on the early dynamics of genomes following rearrangement and illustrates how secondary chromosomes in bacteria may become evolutionary test beds.
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Affiliation(s)
- Jarrett D Morrow
- Department of Molecular, Cellular, and Biomedical Sciences, University of New Hampshire, NH, USA
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The tRNAarg gene and engA are essential genes on the 1.7-Mb pSymB megaplasmid of Sinorhizobium meliloti and were translocated together from the chromosome in an ancestral strain. J Bacteriol 2012; 195:202-12. [PMID: 23123907 DOI: 10.1128/jb.01758-12] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacterial genomes with two (or more) chromosome-like replicons are known, and these appear to be particularly frequent in alphaproteobacteria. The genome of the N(2)-fixing alfalfa symbiont Sinorhizobium meliloti 1021 contains a 3.7-Mb chromosome and 1.4-Mb (pSymA) and 1.7-Mb (pSymB) megaplasmids. In this study, the tRNA(arg) and engA genes, located on the pSymB megaplasmid, are shown to be essential for growth. These genes could be deleted from pSymB when copies were previously integrated into the chromosome. However, in the closely related strain Sinorhizobium fredii NGR234, the tRNA(arg) and engA genes are located on the chromosome, in a 69-kb region designated the engA-tRNA(arg)-rmlC region. This region includes bacA, a gene that is important for intracellular survival during host-bacterium interactions for S. meliloti and the related alphaproteobacterium Brucella abortus. The engA-tRNA(arg)-rmlC region lies between the kdgK and dppF2 (NGR_c24410) genes on the S. fredii chromosome. Synteny analysis showed that kdgK and dppF2 orthologues are adjacent to each other on the chromosomes of 15 sequenced strains of S. meliloti and Sinorhizobium medicae, whereas the 69-kb engA-tRNA(arg)-rmlC region is present on the pSymB-equivalent megaplasmids. This and other evidence strongly suggests that the engA-tRNA(arg)-rmlC region translocated from the chromosome to the progenitor of pSymB in an ancestor common to S. meliloti and S. medicae. To our knowledge, this work represents one of the first experimental demonstrations that essential genes are present on a megaplasmid.
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[Current status of theoretical studies on essential genes in microbes]. YI CHUAN = HEREDITAS 2012; 34:420-30. [PMID: 22522159 DOI: 10.3724/sp.j.1005.2012.00420] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Essential genes are indispensable for the survival of an organism in optimal conditions. Recently, study on essential gene is becoming a hot topic of microbiology, genomics, and bioinformatics. This paper described the experiments that determined essential genes in some microbes and the theoretical researches on essential genes were reviewed. The major content contained comparison of essential genes and non-essential genes based on information on evolutionary conservation and sequence composition, and in silico prediction of essential genes, and analysis of the chromosomal distributions of essential genes. Finally, related progresses were concluded and the open problems were pointed out.
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