1
|
Devlin T, Marx DC, Roskopf MA, Bubb QR, Plummer AM, Fleming KG. FkpA enhances membrane protein folding using an extensive interaction surface. Protein Sci 2023; 32:e4592. [PMID: 36775935 PMCID: PMC10031210 DOI: 10.1002/pro.4592] [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: 09/27/2022] [Revised: 01/17/2023] [Accepted: 02/07/2023] [Indexed: 02/14/2023]
Abstract
Outer membrane protein (OMP) biogenesis in gram-negative bacteria is managed by a network of periplasmic chaperones that includes SurA, Skp, and FkpA. These chaperones bind unfolded OMPs (uOMPs) in dynamic conformational ensembles to suppress aggregation, facilitate diffusion across the periplasm, and enhance folding. FkpA primarily responds to heat-shock stress, but its mechanism is comparatively understudied. To determine FkpA chaperone function in the context of OMP folding, we monitored the folding of three OMPs and found that FkpA, unlike other periplasmic chaperones, increases the folded yield but decreases the folding rate of OMPs. The results indicate that FkpA behaves as a chaperone and not as a folding catalyst to influence the OMP folding trajectory. Consistent with the folding assay results, FkpA binds all three uOMPs as determined by sedimentation velocity (SV) and photo-crosslinking experiments. We determine the binding affinity between FkpA and uOmpA171 by globally fitting SV titrations and find it to be intermediate between the known affinities of Skp and SurA for uOMP clients. Notably, complex formation steeply depends on the urea concentration, suggesting an extensive binding interface. Initial characterizations of the complex using photo-crosslinking indicate that the binding interface spans the entire FkpA molecule. In contrast to prior findings, folding and binding experiments performed using subdomain constructs of FkpA demonstrate that the full-length chaperone is required for full activity. Together these results support that FkpA has a distinct and direct effect on OMP folding that it achieves by utilizing an extensive chaperone-client interface to tightly bind clients.
Collapse
Affiliation(s)
- Taylor Devlin
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Dagan C. Marx
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Michaela A. Roskopf
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Quenton R. Bubb
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Ashlee M. Plummer
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| | - Karen G. Fleming
- T.C. Jenkins Department of BiophysicsJohns Hopkins UniversityBaltimoreMarylandUSA
| |
Collapse
|
2
|
SurA-like and Skp-like Proteins as Important Virulence Determinants of the Gram Negative Bacterial Pathogens. Int J Mol Sci 2022; 24:ijms24010295. [PMID: 36613738 PMCID: PMC9820271 DOI: 10.3390/ijms24010295] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2022] [Revised: 12/19/2022] [Accepted: 12/20/2022] [Indexed: 12/28/2022] Open
Abstract
In the Gram-negative bacteria, many important virulence factors reach their destination via two-step export systems, and they must traverse the periplasmic space before reaching the outer membrane. Since these proteins must be maintained in a structure competent for transport into or across the membrane, they frequently require the assistance of chaperones. Based on the results obtained for the model bacterium Escherichia coli and related species, it is assumed that in the biogenesis of the outer membrane proteins and the periplasmic transit of secretory proteins, the SurA peptidyl-prolyl isomerase/chaperone plays a leading role, while the Skp chaperone is rather of secondary importance. However, detailed studies carried out on several other Gram-negative pathogens indicate that the importance of individual chaperones in the folding and transport processes depends on the properties of client proteins and is species-specific. Taking into account the importance of SurA functions in bacterial virulence and severity of phenotypes due to surA mutations, this folding factor is considered as a putative therapeutic target to combat microbial infections. In this review, we present recent findings regarding SurA and Skp proteins: their mechanisms of action, involvement in processes related to virulence, and perspectives to use them as therapeutic targets.
Collapse
|
3
|
Abstract
Vitamin B6 is an ensemble of six interconvertible vitamers: pyridoxine (PN), pyridoxamine (PM), pyridoxal (PL), and their 5'-phosphate derivatives, PNP, PMP, and PLP. Pyridoxal 5'-phosphate is a coenzyme in a variety of enzyme reactions concerning transformations of amino and amino acid compounds. This review summarizes all known and putative PLP-binding proteins found in the Escherichia coli MG1655 proteome. PLP can have toxic effects since it contains a very reactive aldehyde group at its 4' position that easily forms aldimines with primary and secondary amines and reacts with thiols. Most PLP is bound either to the enzymes that use it as a cofactor or to PLP carrier proteins, protected from the cellular environment but at the same time readily transferable to PLP-dependent apoenzymes. E. coli and its relatives synthesize PLP through the seven-step deoxyxylulose-5-phosphate (DXP)-dependent pathway. Other bacteria synthesize PLP in a single step, through a so-called DXP-independent pathway. Although the DXP-dependent pathway was the first to be revealed, the discovery of the widespread DXP-independent pathway determined a decline of interest in E. coli vitamin B6 metabolism. In E. coli, as in most organisms, PLP can also be obtained from PL, PN, and PM, imported from the environment or recycled from protein turnover, via a salvage pathway. Our review deals with all aspects of vitamin B6 metabolism in E. coli, from transcriptional to posttranslational regulation. A critical interpretation of results is presented, in particular, concerning the most obscure aspects of PLP homeostasis and delivery to PLP-dependent enzymes.
Collapse
|
4
|
Marx DC, Plummer AM, Faustino AM, Devlin T, Roskopf MA, Leblanc MJ, Lessen HJ, Amann BT, Fleming PJ, Krueger S, Fried SD, Fleming KG. SurA is a cryptically grooved chaperone that expands unfolded outer membrane proteins. Proc Natl Acad Sci U S A 2020; 117:28026-28035. [PMID: 33093201 PMCID: PMC7668074 DOI: 10.1073/pnas.2008175117] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2020] [Accepted: 08/26/2020] [Indexed: 11/18/2022] Open
Abstract
The periplasmic chaperone network ensures the biogenesis of bacterial outer membrane proteins (OMPs) and has recently been identified as a promising target for antibiotics. SurA is the most important member of this network, both due to its genetic interaction with the β-barrel assembly machinery complex as well as its ability to prevent unfolded OMP (uOMP) aggregation. Using only binding energy, the mechanism by which SurA carries out these two functions is not well-understood. Here, we use a combination of photo-crosslinking, mass spectrometry, solution scattering, and molecular modeling techniques to elucidate the key structural features that define how SurA solubilizes uOMPs. Our experimental data support a model in which SurA binds uOMPs in a groove formed between the core and P1 domains. This binding event results in a drastic expansion of the rest of the uOMP, which has many biological implications. Using these experimental data as restraints, we adopted an integrative modeling approach to create a sparse ensemble of models of a SurA•uOMP complex. We validated key structural features of the SurA•uOMP ensemble using independent scattering and chemical crosslinking data. Our data suggest that SurA utilizes three distinct binding modes to interact with uOMPs and that more than one SurA can bind a uOMP at a time. This work demonstrates that SurA operates in a distinct fashion compared to other chaperones in the OMP biogenesis network.
Collapse
Affiliation(s)
- Dagan C Marx
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Ashlee M Plummer
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | | | - Taylor Devlin
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Michaela A Roskopf
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Mathis J Leblanc
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Henry J Lessen
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Barbara T Amann
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Patrick J Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218
| | - Susan Krueger
- National Institute of Standards and Technology, Gaithersburg, MD 20899
| | - Stephen D Fried
- Department of Chemistry, Johns Hopkins University, Baltimore, MD 21218
| | - Karen G Fleming
- Thomas C. Jenkins Department of Biophysics, Johns Hopkins University, Baltimore, MD 21218;
| |
Collapse
|
5
|
Wang YK, Krasnopeeva E, Lin SY, Bai F, Pilizota T, Lo CJ. Comparison of Escherichia coli surface attachment methods for single-cell microscopy. Sci Rep 2019; 9:19418. [PMID: 31857669 PMCID: PMC6923479 DOI: 10.1038/s41598-019-55798-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 11/05/2019] [Indexed: 12/22/2022] Open
Abstract
For in vivo, single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment. Different surface attachment methods have been used both for atomic force and optical microscopy (including super resolution), and some have been reported to affect bacterial physiology. However, a systematic comparison of the effects these attachment methods have on the bacterial physiology is lacking. Here we present such a comparison for bacterium Escherichia coli, and assess the growth rate, size and intracellular pH of cells growing attached to different, commonly used, surfaces. We demonstrate that E. coli grow at the same rate, length and internal pH on all the tested surfaces when in the same growth medium. The result suggests that tested attachment methods can be used interchangeably when studying E. coli physiology.
Collapse
Affiliation(s)
- Yao-Kuan Wang
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China
| | - Ekaterina Krasnopeeva
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, EH9 3FF, Edinburgh, UK
| | - Ssu-Yuan Lin
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China
| | - Fan Bai
- Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing, 100871, China
| | - Teuta Pilizota
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, EH9 3FF, Edinburgh, UK.
| | - Chien-Jung Lo
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China.
| |
Collapse
|
6
|
Pandey S, Delgado C, Kumari H, Florez L, Mathee K. Outer-membrane protein LptD (PA0595) plays a role in the regulation of alginate synthesis in Pseudomonas aeruginosa. J Med Microbiol 2018; 67:1139-1156. [PMID: 29923820 DOI: 10.1099/jmm.0.000752] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
PURPOSE The presence of alginate-overproducing (Alg+) strains of Pseudomonas aeruginosa in cystic fibrosis patients is indicative of chronic infection. The Alg+ phenotype is generally due to a mutation in the mucA gene, encoding an innermembrane protein that sequesters AlgT/U, the alginate-specific sigma factor. AlgT/U release from the anti-sigma factor MucA is orchestrated via a complex cascade called regulated intramembrane proteolysis. The goal of this study is to identify new players involved in the regulation of alginate production. METHODOLOGY Previously, a mutant with a second-site suppressor of alginate production (sap), sap27, was isolated from the constitutively Alg+ PDO300 that harbours the mucA22 allele. A cosmid from a P. aeruginosa minimum tiling path library was identified via en masse complementation of sap27. The cosmid was transposon mutagenized to map the contributing gene involved in the alginate production. The identified gene was sequenced in sap27 along with algT/U, mucA, algO and mucP. The role of the novel gene was explored using precise in-frame algO and algW deletion mutants of PAO1 and PDO300.Results/Key findings. The gene responsible for restoring the mucoid phenotype was mapped to lptD encoding an outer-membrane protein. However, the sequencing of sap27 revealed a mutation in algO, but not in lptD. In addition, we demonstrate that lipopolysaccharide transport protein D (LptD)-dependent alginate production requires AlgW in PAO1 and AlgO in PDO300. CONCLUSION LptD plays a specific role in alginate production. Our findings suggest that there are two pathways for the production of alginate in P. aeruginosa, one involving AlgW in the wild-type, and one involving AlgO in the mucA22 mutant.
Collapse
Affiliation(s)
- Sundar Pandey
- 1Department of Biological Sciences, College of Arts Sciences and Education, Florida International University, Miami, FL, USA
| | - Camila Delgado
- 2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,†Present address: Langone Medical Center, New York University School of Medicine, New York, USA
| | - Hansi Kumari
- 2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,3Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Laura Florez
- 2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| | - Kalai Mathee
- 4Biomolecular Sciences Institute, Florida International University, Miami, FL, USA.,2Department of Microbiology and Infectious Diseases, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA.,3Department of Human and Molecular Genetics, Herbert Wertheim College of Medicine, Florida International University, Miami, FL, USA
| |
Collapse
|
7
|
Kim SK, Park YM, Jung KH, Chai YG. Deletion of a putative NlpC/P60 endopeptidase BAS1812 affects germination, long-term survival and endospore formation in Bacillus anthracis. MICROBIOLOGY-SGM 2016; 163:144-152. [PMID: 28008818 DOI: 10.1099/mic.0.000416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Bacillus anthracis, an aetiologic agent of the zoonotic disease anthrax, encodes a putative NlpC/P60 endopeptidase BAS1812. It harbours a signal peptide, three bacterial SH3 domains and an NlpC/P60 family domain. Previous studies showed that BAS1812 is immunogenic in infected hosts and is a potential biomarker for anthrax treatment. To date, however, little information is known about its function and involvement in anthrax pathogenesis. Here we describe the phenotypic effect of BAS1812 deletion in B. anthracis Sterne strain. Transcriptional analysis showed that BAS1812 expression in a host-like environment was enhanced at the end of log phase, started to diminish after entry to stationary phase and increased again late in stationary phase. The constructed BAS1812 mutant showed impaired long-term survival in the stationary growth phase, less resilience to detergent, lesser endospore formation and delayed germination. The mutant also showed diminished ability to degrade peptidoglycan, but its ability to produce anthrax exotoxins was not affected. We hypothesize that BAS1812 is a cell wall hydrolase involved in biological activities related to maintaining cell wall integrity, sporulation and spore germination.
Collapse
Affiliation(s)
- Se Kye Kim
- Department of Molecular and Life Science, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Yun Min Park
- Department of Molecular and Life Science, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Kyoung Hwa Jung
- Department of Molecular and Life Science, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Young Gyu Chai
- Department of Bionanotechnology, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, Seoul 04763, Republic of Korea.,Department of Molecular and Life Science, Hanyang University, 55 Hanyangdaehak-ro, Sangnok-gu, Ansan, Gyeonggi-do 15588, Republic of Korea
| |
Collapse
|
8
|
Dynamic periplasmic chaperone reservoir facilitates biogenesis of outer membrane proteins. Proc Natl Acad Sci U S A 2016; 113:E4794-800. [PMID: 27482090 DOI: 10.1073/pnas.1601002113] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Outer membrane protein (OMP) biogenesis is critical to bacterial physiology because the cellular envelope is vital to bacterial pathogenesis and antibiotic resistance. The process of OMP biogenesis has been studied in vivo, and each of its components has been studied in isolation in vitro. This work integrates parameters and observations from both in vivo and in vitro experiments into a holistic computational model termed "Outer Membrane Protein Biogenesis Model" (OMPBioM). We use OMPBioM to assess OMP biogenesis mathematically in a global manner. Using deterministic and stochastic methods, we are able to simulate OMP biogenesis under varying genetic conditions, each of which successfully replicates experimental observations. We observe that OMPs have a prolonged lifetime in the periplasm where an unfolded OMP makes, on average, hundreds of short-lived interactions with chaperones before folding into its native state. We find that some periplasmic chaperones function primarily as quality-control factors; this function complements the folding catalysis function of other chaperones. Additionally, the effective rate for the β-barrel assembly machinery complex necessary for physiological folding was found to be higher than has currently been observed in vitro. Overall, we find a finely tuned balance between thermodynamic and kinetic parameters maximizes OMP folding flux and minimizes aggregation and unnecessary degradation. In sum, OMPBioM provides a global view of OMP biogenesis that yields unique insights into this essential pathway.
Collapse
|
9
|
Chai Q, Ferrell B, Zhong M, Zhang X, Ye C, Wei Y. Diverse sequences are functional at the C-terminus of the E. coli periplasmic chaperone SurA. Protein Eng Des Sel 2014; 27:111-6. [PMID: 24586054 DOI: 10.1093/protein/gzu003] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
SurA is a major periplasmic molecular chaperone in Escherichia coli and has been shown to assist the biogenesis of several outer membrane proteins. The C-terminal fragment of SurA folds into a short β-strand, which forms a small three-stranded anti-parallel β-sheet module with the N-terminal β-hairpin. We found that the length of the C-terminal fragment, rather than its exact amino acid composition, had a big impact on SurA function. To investigate the determinant factor of the C-terminal sequence, we created a library of SurA constructs randomized in the last 10 residues. We screened the library and randomly analyzed 19 constructs that displayed SurA activity. The C-termini of these constructs shared little sequence similarity, except that β-strand-forming residues were preferentially enriched. Three SurA constructs were expressed and purified for structural characterization. Circular dichroism and fluorescence spectroscopy analyses revealed that their structures were similar to the structure of the wild-type SurA. Our results suggest that for scaffolding purpose proteins may tolerate various sequences provided certain general requirements such as hydrophobicity and secondary structure propensity are satisfied. Furthermore, the sequence tolerance of SurA at the C-terminus indicates that this area is not likely to be involved in substrate binding.
Collapse
Affiliation(s)
- Qian Chai
- Department of Chemistry, University of Kentucky, 305 Chemistry-Physics Building, Lexington, KY 40506-0055, USA
| | | | | | | | | | | |
Collapse
|
10
|
Effect of acidic condition on the metabolic regulation of Escherichia coli and its phoB mutant. Arch Microbiol 2012; 195:161-71. [DOI: 10.1007/s00203-012-0861-7] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Revised: 12/05/2012] [Accepted: 12/06/2012] [Indexed: 10/27/2022]
|
11
|
Insights into the function and structural flexibility of the periplasmic molecular chaperone SurA. J Bacteriol 2012; 195:1061-7. [PMID: 23275244 DOI: 10.1128/jb.01143-12] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SurA is the primary periplasmic molecular chaperone that facilitates the folding and assembling of outer membrane proteins (OMPs) in Gram-negative bacteria. Deletion of the surA gene in Escherichia coli leads to a decrease in outer membrane density and an increase in bacterial drug susceptibility. Here, we conducted mutational studies on SurA to identify residues that are critical for function. One mutant, SurA(V37G), significantly reduced the activity of SurA. Further characterization indicated that SurA(V37G) was structurally similar to, but less stable than, the wild-type protein. The loss of activity in SurA(V37G) could be restored through the introduction of a pair of Cys residues and the subsequent formation of a disulfide bond. Inspired by this success, we created three additional SurA constructs, each containing a disulfide bond at different regions of the protein between two rigid secondary structural elements. The formation of disulfide bond in these mutants has no observable detrimental effect on protein activity, indicating that SurA does not undergo large-scale conformational change while performing its function.
Collapse
|
12
|
The role of SurA factor in outer membrane protein transport and virulence. Int J Med Microbiol 2010; 300:421-8. [PMID: 20447864 DOI: 10.1016/j.ijmm.2010.04.012] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Revised: 03/16/2010] [Accepted: 04/05/2010] [Indexed: 11/22/2022] Open
Abstract
The Escherichia coli periplasmic chaperone and peptidyl-prolyl isomerase (PPIase) SurA is a major factor in the biogenesis of β-barrel outer membrane proteins (OMPs) and as such plays an integral role in cell envelope homeostasis and cell envelope functions. Recently, the biological importance of SurA was further substantiated by the finding that SurA also affects pathogenicity, being required for full virulence of uropathogenic Escherichia coli, Salmonella, and Shigella spp. Moreover, given the conservation of the protein, SurA likely plays similar roles in other Gram-negative bacteria and may hence prove a valuable drug target against Gram-negative pathogens. While our understanding on how SurA promotes transport and folding of β-barrel OMPs, how it provides support to virulence, and how it functions at a molecular level is still limited, major contributions have recently been made on our way to find answers to these questions. This review is a compilation of our current state of knowledge on E. coli SurA function and a discussion of recent findings with a particular emphasis on the pleiotropic contributions of SurA to pathogenicity.
Collapse
|
13
|
Weininger U, Jakob RP, Kovermann M, Balbach J, Schmid FX. The prolyl isomerase domain of PpiD from Escherichia coli shows a parvulin fold but is devoid of catalytic activity. Protein Sci 2010; 19:6-18. [PMID: 19866485 DOI: 10.1002/pro.277] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
PpiD is a periplasmic folding helper protein of Escherichia coli. It consists of an N-terminal helix that anchors PpiD in the inner membrane near the SecYEG translocon, followed by three periplasmic domains. The second domain (residues 264-357) shows homology to parvulin-like prolyl isomerases. This domain is a well folded, stable protein and follows a simple two-state folding mechanism. In its solution structure, as determined by NMR spectroscopy, it resembles most closely the first parvulin domain of the SurA protein, which resides in the periplasm of E. coli as well. A previously reported prolyl isomerase activity of PpiD could not be reproduced when using improved protease-free peptide assays or assays with refolding proteins as substrates. The parvulin domain of PpiD interacts, however, with a proline-containing tetrapeptide, and the binding site, as identified by NMR resonance shift analysis, colocalized with the catalytic sites of other parvulins. In its structure, the parvulin domain of PpiD resembles most closely the inactive first parvulin domain of SurA, which is part of the chaperone unit of this protein and presumably involved in substrate recognition.
Collapse
Affiliation(s)
- Ulrich Weininger
- Institut für Physik, Biophysik, and Mitteldeutsches Zentrum für Struktur und Dynamik der Proteine (MZP), Martin-Luther-Universität Halle-Wittenberg, D-06120 Halle(Saale), Germany
| | | | | | | | | |
Collapse
|
14
|
Periplasmic peptidyl-prolyl isomerases SurA and FkpA play an important role in the starvation-stress response (SSR) of Salmonella enterica serovar Typhimurium. Antonie van Leeuwenhoek 2010; 98:51-63. [PMID: 20232248 DOI: 10.1007/s10482-010-9428-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 03/04/2010] [Indexed: 10/19/2022]
Abstract
Carbon-energy source (C)-starved cells of Salmonella enterica serovar Typhimurium (S. Typhimurium) are remarkably more resistant to stress than actively growing ones. Carbon-starved S. Typhimurium is capable of withstanding extended periods of starvation and assault from a number of different stresses that rapidly kill growing cells. These unique properties of the C-starved cell are the direct result of a series of genetic and physiological adaptations referred to as the starvation-stress response (SSR). Previous work established that the SSR of S. Typhimurium is partially regulated by the extracytoplasmic function sigma factor sigma(E). As part of an effort to identify sigma(E)-regulated SSR genes, we investigated surA and fkpA, encoding two different classes of peptidyl-prolyl isomerase that function in folding cell envelope proteins. Both surA and fkpA are members of the heat-shock-inducible sigma(E) regulon of Escherichia coli. Although both genes are expressed in C-starved Salmonella cells, evidence indicates that surA and fkpA are not C-starvation-inducible. Furthermore, their expression during C-starvation does not appear to be sigma(E)-dependent. Nonetheless, surA and fkpA proved to be important, to differing degrees, for long-term C-starvation survival and for the cross-resistance of C-starved cells to high temperature, acidic pH, and the antimicrobial peptide polymyxin B, but neither were required for cross-resistance to oxidative stress. These results point to fundamental differences between heat-shock-inducible and C-starvation-inducible genes regulated by sigma(E) and suggest that genes other than surA and fkpA are involved in the sigma(E)-regulated branch of the SSR in Salmonella.
Collapse
|
15
|
OmpA of uropathogenic Escherichia coli promotes postinvasion pathogenesis of cystitis. Infect Immun 2009; 77:5245-51. [PMID: 19797074 DOI: 10.1128/iai.00670-09] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Type 1 pilus directs bladder epithelial binding and invasion by uropathogenic Escherichia coli (UPEC) in the initial stage of cystitis, but the bacterial determinants of postinvasion events in the pathogenesis of cystitis are largely undetermined. We show here that the UPEC outer membrane protein A (OmpA), a monomeric, major, integral protein component of the bacterial outer membrane, functions as a critical determinant of intracellular virulence for UPEC, promoting persistent infection within bladder epithelium. Using a murine urinary tract infection (UTI) model, we demonstrate that whereas deletion of the UPEC ompA gene did not disrupt initial epithelial binding and invasion by UPEC, it did preclude completion of the intracellular bacterial community (IBC) pathway, accompanied by diminishing bacterial loads in the bladder. This defect in epithelial persistence of the ompA mutant was enhanced in competitive infections with wild-type UPEC. Microscopic examinations revealed that the ompA mutant formed significantly fewer IBCs, and those that were initiated were unable to progress past the early stages of maturation. These defects could be corrected by complementation of ompA. In addition, expression of ompA during wild-type UTI was sharply increased at time points correlated with IBC development and the arrival of host immune effector cells. Our findings establish OmpA as a key UPEC virulence factor that functions after epithelial invasion to facilitate IBC maturation and chronic bacterial persistence.
Collapse
|
16
|
Trotsenko YA, Torgonskaya ML. The aerobic degradation of dichloromethane: Structural-functional aspects (a review). APPL BIOCHEM MICRO+ 2009. [DOI: 10.1134/s0003683809030016] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
|
17
|
Kwiatkowska J, Matuszewska E, Kuczyńska-Wiśnik D, Laskowska E. Aggregation of Escherichia coli proteins during stationary phase depends on glucose and oxygen availability. Res Microbiol 2008; 159:651-7. [DOI: 10.1016/j.resmic.2008.09.008] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2008] [Revised: 09/11/2008] [Accepted: 09/22/2008] [Indexed: 11/29/2022]
|
18
|
Streit F, Delettre J, Corrieu G, Béal C. Acid adaptation ofLactobacillus delbrueckiisubsp.bulgaricusinduces physiological responses at membrane and cytosolic levels that improves cryotolerance. J Appl Microbiol 2008; 105:1071-80. [DOI: 10.1111/j.1365-2672.2008.03848.x] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
19
|
Wohlkönig A, Hodak H, Clantin B, Sénéchal M, Bompard C, Jacob-Dubuisson F, Villeret V. Crystallization and preliminary X-ray diffraction analysis of the peptidylprolyl isomerase Par27 of Bordetella pertussis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2008; 64:809-12. [PMID: 18765910 DOI: 10.1107/s1744309108024731] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2008] [Accepted: 08/01/2008] [Indexed: 11/10/2022]
Abstract
Proteins with both peptidylprolyl isomerase (PPIase) and chaperone activities play a crucial role in protein folding in the periplasm of Gram-negative bacteria. Few such proteins have been structurally characterized and to date only the crystal structure of SurA from Escherichia coli has been reported. Par27, the prototype of a new group of parvulins, has recently been identified. Par27 exhibits both chaperone and PPIase activities in vitro and is the first identified parvulin protein that forms dimers in solution. Par27 has been expressed in E. coli. The protein was purified using affinity and gel-filtration chromatographic techniques and crystallized in two different crystal forms. Form A, which belongs to space group P2 (unit-cell parameters a = 42.2, b = 142.8, c = 56.0 A, beta = 95.1 degrees ), diffracts to 2.8 A resolution, while form B, which belongs to space group C222 (unit-cell parameters a = 54.6, b = 214.1, c = 57.8 A), diffracts to 2.2 A resolution. Preliminary diffraction data analysis agreed with the presence of one monomer in the asymmetric unit of the orthorhombic crystal form and two in the monoclinic form.
Collapse
Affiliation(s)
- Alexandre Wohlkönig
- Approches Structurales et Fonctionnelles de Pathogenèse, Institut de Biologie de Lille, Institut Pasteur de Lille, Université de Lille 1, Université de Lille 2, IFR142, 1 Rue du Professeur Calmette, BP245 Lille 59021 CEDEX, France
| | | | | | | | | | | | | |
Collapse
|
20
|
Armalytė J, Šeputienė V, Melefors Ö, Sužiedėlienė E. An Escherichia coli asr mutant has decreased fitness during colonization in a mouse model. Res Microbiol 2008; 159:486-93. [DOI: 10.1016/j.resmic.2008.06.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2008] [Revised: 06/05/2008] [Accepted: 06/06/2008] [Indexed: 11/28/2022]
|
21
|
Stymest KH, Klappa P. The periplasmic peptidyl prolyl cis-trans isomerases PpiD and SurA have partially overlapping substrate specificities. FEBS J 2008; 275:3470-9. [PMID: 18498364 DOI: 10.1111/j.1742-4658.2008.06493.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
One of the rate-limiting steps in protein folding has been shown to be the cis-trans isomerization of proline residues, catalysed by a range of peptidyl prolyl cis-trans isomerases (PPIases). In the periplasmic space of Escherichia coli and other Gram-negative bacteria, two PPIases, SurA and PpiD, have been identified, which show high sequence similarity to the catalytic domain of the small PPIase parvulin. This observation raises a question regarding the biological significance of two apparently similar enzymes present in the same cellular compartment: do they interact with different substrates or do they catalyse different reactions? The substrate-binding motif of PpiD has not been characterized so far, and no biochemical data were available on how this folding catalyst recognizes and interacts with substrates. To characterize the interaction between model peptides and the periplasmic PPIase PpiD from E. coli, we employed a chemical crosslinking strategy that has been used previously to elucidate the interaction of substrates with SurA. We found that PpiD interacted with a range of model peptides independently of whether they contained proline residues or not. We further demonstrate here that PpiD and SurA interact with similar model peptides, and therefore must have partially overlapping substrate specificities. However, the binding motif of PpiD appears to be less specific than that of SurA, indicating that the two PPIases might interact with different substrates. We therefore propose that, although PpiD and SurA have partially overlapping substrate specificities, they fulfil different functions in the cell.
Collapse
|
22
|
Hodak H, Wohlkönig A, Smet-Nocca C, Drobecq H, Wieruszeski JM, Sénéchal M, Landrieu I, Locht C, Jamin M, Jacob-Dubuisson F. The Peptidyl–Prolyl Isomerase and Chaperone Par27 of Bordetella pertussis as the Prototype for a New Group of Parvulins. J Mol Biol 2008; 376:414-26. [DOI: 10.1016/j.jmb.2007.10.088] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2007] [Revised: 10/26/2007] [Accepted: 10/31/2007] [Indexed: 11/15/2022]
|
23
|
Castanié-Cornet MP, Cam K, Jacq A. RcsF is an outer membrane lipoprotein involved in the RcsCDB phosphorelay signaling pathway in Escherichia coli. J Bacteriol 2006; 188:4264-70. [PMID: 16740933 PMCID: PMC1482940 DOI: 10.1128/jb.00004-06] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The RcsCDB signal transduction system is an atypical His-Asp phosphorelay conserved in gamma-proteobacteria. Besides the three proteins directly involved in the phosphorelay, two proteins modulate the activity of the system. One is RcsA, which can stimulate the activity of the response regulator RcsB independently of the phosphorelay to regulate a subset of RcsB targets. The other is RcsF, a putative outer membrane lipoprotein mediating the signaling to the sensor RcsC. How RcsF transduces the signal to RcsC is unknown. Although the molecular and physiological signals remain to be identified, the common feature among the reported Rcs-activating conditions is perturbation of the envelope. As an initial step to explore the RcsF-RcsC functional relationship, we demonstrate that RcsF is an outer membrane lipoprotein oriented towards the periplasm. We also report that a null mutation in surA, a gene required for correct folding of periplasmic proteins, activates the Rcs pathway through RcsF. In contrast, activation of this pathway by overproduction of the membrane chaperone-like protein DjlA does not require RcsF. Conversely, activation of the pathway by RcsF overproduction does not require DjlA either, indicating the existence of two independent signaling pathways toward RcsC.
Collapse
Affiliation(s)
- Marie-Pierre Castanié-Cornet
- Institut de Génétique et de Microbiologie, UMR 8621, Centre National de la Recherche Scientifique and Université Paris-Sud, Bâtiment 400, 91 405 Orsay cedex, France
| | | | | |
Collapse
|
24
|
Lee JW, Lee SY, Song H, Yoo JS. The proteome ofMannheimia succiniciproducens, a capnophilic rumen bacterium. Proteomics 2006; 6:3550-66. [PMID: 16758448 DOI: 10.1002/pmic.200500837] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mannheimia succiniciproducens MBEL55E isolated from bovine rumen is an industrially important bacterium as an efficient succinic acid producer. Recently, its full genome sequence was determined. In the present study, we analyzed the M. succiniciproducens proteome based on the genome information using 2-DE and MS. We established proteome reference map of M. succiniciproducens by analyzing whole cellular proteins, membrane proteins, and secreted proteins. More than 200 proteins were identified and characterized by MS/MS supported by various bioinformatic tools. The presence of proteins previously annotated as hypothetical proteins or proteins having putative functions were also confirmed. Based on the proteome reference map, cells in the different growth phases were analyzed at the proteome level. Comparative proteome profiling revealed valuable information to understand physiological changes during growth, and subsequently suggested target genes to be manipulated for the strain improvement.
Collapse
Affiliation(s)
- Jeong Wook Lee
- Department of Chemical & Biomolecular Engineering, Metabolic and Biomolecular Engineering National Research Laboratory, BioProcess Engineering Research Center, Korea Advanced Institute of Science and Technology, Daejeon, Republic of Korea
| | | | | | | |
Collapse
|
25
|
Aguirre-Ramírez M, Ramírez-Santos J, Van Melderen L, Gómez-Eichelmann MC. Expression of the F plasmid ccd toxin-antitoxin system in Escherichia coli cells under nutritional stress. Can J Microbiol 2006; 52:24-30. [PMID: 16541156 DOI: 10.1139/w05-107] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The ccd system of the F plasmid encodes CcdB, a protein toxic to DNA-gyrase, and CcdA, its antitoxin. The function attributed to this system is to contribute to plasmid stability by killing bacteria that lose the plasmid during cell division. However, the function of ccd in resting bacteria is not clear. Results presented show that ccd transcription increases as bacteria enter stationary phase and that the amount of the Ccd proteins is higher in bacteria under nutritional stress than in growing bacteria. Moreover, an increase in the frequency of Lac+ "adaptive" mutations was observed in stationary-phase bacteria that over-express the Ccd proteins.
Collapse
Affiliation(s)
- Marisela Aguirre-Ramírez
- Departamento de Biologia Molecular Biotecnología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, DF México
| | | | | | | |
Collapse
|
26
|
Boshoff HI, Barry CE. Is the mycobacterial cell wall a hopeless drug target for latent tuberculosis? ACTA ACUST UNITED AC 2006. [DOI: 10.1016/j.ddmec.2006.06.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
|
27
|
Hicks WM, Kotlajich MV, Visick JE. Recovery from long-term stationary phase and stress survival in Escherichia coli require the L-isoaspartyl protein carboxyl methyltransferase at alkaline pH. MICROBIOLOGY-SGM 2005; 151:2151-2158. [PMID: 16000706 DOI: 10.1099/mic.0.27835-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The L-isoaspartyl protein carboxyl methyltransferase (pcm) can stimulate repair of isoaspartyl residues arising spontaneously in proteins to normal L-aspartyl residues. PCM is needed in Escherichia coli for maximal long-term survival when exposed to oxidative stress, osmotic stress, repeated heat stress or methanol. The effect of pH on a pcm mutant during long-term stationary phase was examined. PCM was not required for long-term survival of E. coli subjected to pH stress alone; however, PCM-deficient cells showed impaired resistance to paraquat and methanol only at elevated pH. The mutant also showed stress-survival phenotypes in minimal medium buffered to pH 9.0. Accumulation of isoaspartyl residues was accelerated at pH 8.0 or 9.0 in vivo, though PCM-deficient cells did not show higher levels of damage. However, the pcm mutant displayed an extended lag phase in recovering from stationary phase at pH 9.0. Protein repair by PCM thus plays a key role in long-term stress survival only at alkaline pH in E. coli, and it may function primarily to repair damage in cells that are recovering from nutrient limitation and in those cells that are able to divide during long-term stationary phase.
Collapse
Affiliation(s)
- Wade M Hicks
- Department of Biology, North Central College, Naperville, IL 60540, USA
| | | | - Jonathan E Visick
- Department of Biology, North Central College, Naperville, IL 60540, USA
| |
Collapse
|
28
|
Cuny C, Dukan L, Fraysse L, Ballesteros M, Dukan S. Investigation of the first events leading to loss of culturability during Escherichia coli starvation: future nonculturable bacteria form a subpopulation. J Bacteriol 2005; 187:2244-8. [PMID: 15774865 PMCID: PMC1065215 DOI: 10.1128/jb.187.7.2244-2248.2005] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In previous experiments we were able to separate, using a nondestructive separation technique, culturable and nonculturable bacteria, from a Luria-Bertani (LB) medium culture of Escherichia coli incubated for 48 h. We observed in the nonculturable bacterial population an increase in oxidative damage and up-induction of most defenses against reactive oxygen species (ROS), along with a decrease in cytoplasmic superoxide dismutases. In this study, using the same separation technique, we separated into two subpopulations a 10-h LB medium culture containing only culturable bacteria. For the first time, we succeeded in associating physical separation with physiological differences. Although the levels of defense against ROS (RpoS, RpoH, OxyR, and SoxRS regulons) and oxidative damage (carbonyl contents) were apparently the same, we found that bacteria in one subpopulation were more sensitive to LB medium starvation and to various stresses, such as phosphate buffer starvation, heat shock, and hydrogen peroxide exposure. Based on these results, we suggest that these physiological differences reflect uncharacterized bacterial modifications which do not directly involve defenses against ROS.
Collapse
Affiliation(s)
- Caroline Cuny
- Laboratoire de Chimie Bactérienne-UPR 9043-CNRS, 31 Chemin Joseph Aiguier, 13402 Marseille cedex 20, France
| | | | | | | | | |
Collapse
|
29
|
Ravagnani A, Finan CL, Young M. A novel firmicute protein family related to the actinobacterial resuscitation-promoting factors by non-orthologous domain displacement. BMC Genomics 2005; 6:39. [PMID: 15774001 PMCID: PMC1084345 DOI: 10.1186/1471-2164-6-39] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2004] [Accepted: 03/17/2005] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND In Micrococcus luteus growth and resuscitation from starvation-induced dormancy is controlled by the production of a secreted growth factor. This autocrine resuscitation-promoting factor (Rpf) is the founder member of a family of proteins found throughout and confined to the actinobacteria (high G + C Gram-positive bacteria). The aim of this work was to search for and characterise a cognate gene family in the firmicutes (low G + C Gram-positive bacteria) and obtain information about how they may control bacterial growth and resuscitation. RESULTS In silico analysis of the accessory domains of the Rpf proteins permitted their classification into several subfamilies. The RpfB subfamily is related to a group of firmicute proteins of unknown function, represented by YabE of Bacillus subtilis. The actinobacterial RpfB and firmicute YabE proteins have very similar domain structures and genomic contexts, except that in YabE, the actinobacterial Rpf domain is replaced by another domain, which we have called Sps. Although totally unrelated in both sequence and secondary structure, the Rpf and Sps domains fulfil the same function. We propose that these proteins have undergone "non-orthologous domain displacement", a phenomenon akin to "non-orthologous gene displacement" that has been described previously. Proteins containing the Sps domain are widely distributed throughout the firmicutes and they too fall into a number of distinct subfamilies. Comparative analysis of the accessory domains in the Rpf and Sps proteins, together with their weak similarity to lytic transglycosylases, provide clear evidence that they are muralytic enzymes. CONCLUSIONS The results indicate that the firmicute Sps proteins and the actinobacterial Rpf proteins are cognate and that they control bacterial culturability via enzymatic modification of the bacterial cell envelope.
Collapse
Affiliation(s)
- Adriana Ravagnani
- Institute of Biological Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3DD, UK
| | - Christopher L Finan
- Institute of Biological Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3DD, UK
| | - Michael Young
- Institute of Biological Sciences, University of Wales, Aberystwyth, Ceredigion SY23 3DD, UK
| |
Collapse
|
30
|
Stokes NR, Murray HD, Subramaniam C, Gourse RL, Louis P, Bartlett W, Miller S, Booth IR. A role for mechanosensitive channels in survival of stationary phase: regulation of channel expression by RpoS. Proc Natl Acad Sci U S A 2003; 100:15959-64. [PMID: 14671322 PMCID: PMC307675 DOI: 10.1073/pnas.2536607100] [Citation(s) in RCA: 94] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2003] [Indexed: 11/18/2022] Open
Abstract
The mechanosensitive (MS) channels MscS and MscL are essential for the survival of hypoosmotic shock by Escherichia coli cells. We demonstrate that MscS and MscL are induced by osmotic stress and by entry into stationary phase. Reduced levels of MS proteins and reduced expression of mscL- and mscS-LacZ fusions in an rpoS mutant strain suggested that the RNA polymerase holoenzyme containing sigmaS is responsible, at least in part, for regulating production of MS channel proteins. Consistent with the model that the effect of sigmaS is direct, the MscS and MscL promoters both use RNA polymerase containing sigmaS in vitro. Conversely, clpP or rssB mutations, which cause enhanced levels of sigmaS, show increased MS channel protein synthesis. RpoS null mutants are sensitive to hypoosmotic shock upon entry into stationary phase. These data suggest that MscS and MscL are components of the RpoS regulon and play an important role in ensuring structural integrity in stationary phase bacteria.
Collapse
Affiliation(s)
- Neil R Stokes
- Department of Molecular and Cell Biology, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, Scotland, United Kingdom
| | | | | | | | | | | | | | | |
Collapse
|
31
|
Molina PM, Parma AE, Sanz ME. Survival in acidic and alcoholic medium of Shiga toxin-producing Escherichia coli O157:H7 and non-O157:H7 isolated in Argentina. BMC Microbiol 2003; 3:17. [PMID: 12914672 PMCID: PMC194472 DOI: 10.1186/1471-2180-3-17] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2003] [Accepted: 08/13/2003] [Indexed: 11/30/2022] Open
Abstract
BACKGROUND In spite of Argentina having one of the highest frequencies of haemolytic uraemic syndrome (HUS), the incidence of Escherichia coli O157:H7 is low in comparison to rates registered in the US. Isolation of several non-O157 shiga toxin-producing Escherichia coli (STEC) strains from cattle and foods suggests that E. coli O157:H7 is an uncommon serotype in Argentina. The present study was undertaken to compare the survival rates of selected non-O157 STEC strains under acidic and alcoholic stress conditions, using an E. coli O157:H7 strain as reference. RESULTS Growth at 37 degrees C of E. coli O26:H11, O88:H21, O91:H21, O111:H-, O113:H21, O116:H21, O117:H7, O157:H7, O171:H2 and OX3:H21, was found to occur at pH higher than 4.0. When the strains were challenged to acid tolerance at pH as low as 2.5, viability extended beyond 8 h, but none of the bacteria, except E. coli O91:H21, could survive longer than 24 h, the autochthonous E. coli O91:H21 being the more resistant serotype. No survival was found after 24 h in Luria Bertani broth supplemented with 12% ethanol, but all these serotypes were shown to be very resistant to 6% ethanol. E. coli O91:H21 showed the highest resistance among serotypes tested. CONCLUSIONS This information is relevant in food industry, which strongly relies on the acid or alcoholic conditions to inactivate pathogens. This study revealed that stress resistance of some STEC serotypes isolated in Argentina is higher than that for E. coli O157:H7.
Collapse
Affiliation(s)
- Pablo M Molina
- Laboratorio de Inmunoquímica y Biotecnología, Animal Health Department, Universidad Nacional del Centro-CIC, Tandil (7000), Argentina
| | - Alberto E Parma
- Laboratorio de Inmunoquímica y Biotecnología, Animal Health Department, Universidad Nacional del Centro-CIC, Tandil (7000), Argentina
| | - Marcelo E Sanz
- Laboratorio de Inmunoquímica y Biotecnología, Animal Health Department, Universidad Nacional del Centro-CIC, Tandil (7000), Argentina
| |
Collapse
|
32
|
SHARMA M, TAORMINA PJ, BEUCHAT LR. Habituation of Foodborne Pathogens Exposed to Extreme pH Conditions: Genetic Basis and Implications in Foods and Food Processing Environments. FOOD SCIENCE AND TECHNOLOGY RESEARCH 2003. [DOI: 10.3136/fstr.9.115] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
33
|
Goffin C, Ghuysen JM. Biochemistry and comparative genomics of SxxK superfamily acyltransferases offer a clue to the mycobacterial paradox: presence of penicillin-susceptible target proteins versus lack of efficiency of penicillin as therapeutic agent. Microbiol Mol Biol Rev 2002; 66:702-38, table of contents. [PMID: 12456788 PMCID: PMC134655 DOI: 10.1128/mmbr.66.4.702-738.2002] [Citation(s) in RCA: 161] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The bacterial acyltransferases of the SxxK superfamily vary enormously in sequence and function, with conservation of particular amino acid groups and all-alpha and alpha/beta folds. They occur as independent entities (free-standing polypeptides) and as modules linked to other polypeptides (protein fusions). They can be classified into three groups. The group I SxxK D,D-acyltransferases are ubiquitous in the bacterial world. They invariably bear the motifs SxxK, SxN(D), and KT(S)G. Anchored in the plasma membrane with the bulk of the polypeptide chain exposed on the outer face of it, they are implicated in the synthesis of wall peptidoglycans of the most frequently encountered (4-->3) type. They are inactivated by penicillin and other beta-lactam antibiotics acting as suicide carbonyl donors in the form of penicillin-binding proteins (PBPs). They are components of a morphogenetic apparatus which, as a whole, controls multiple parameters such as shape and size and allows the bacterial cells to enlarge and duplicate their particular pattern. Class A PBP fusions comprise a glycosyltransferase module fused to an SxxK acyltransferase of class A. Class B PBP fusions comprise a linker, i.e., protein recognition, module fused to an SxxK acyltransferase of class B. They ensure the remodeling of the (4-->3) peptidoglycans in a cell cycle-dependent manner. The free-standing PBPs hydrolyze D,D peptide bonds. The group II SxxK acyltransferases frequently have a partially modified bar code, but the SxxK motif is invariant. They react with penicillin in various ways and illustrate the great plasticity of the catalytic centers. The secreted free-standing PBPs, the serine beta-lactamases, and the penicillin sensors of several penicillin sensory transducers help the D,D-acyltransferases of group I escape penicillin action. The group III SxxK acyltransferases are indistinguishable from the PBP fusion proteins of group I in motifs and membrane topology, but they resist penicillin. They are referred to as Pen(r) protein fusions. Plausible hypotheses are put forward on the roles that the Pen(r) protein fusions, acting as L,D-acyltransferases, may play in the (3-->3) peptidoglycan-synthesizing molecular machines. Shifting the wall peptidoglycan from the (4-->3) type to the (3-->3) type could help Mycobacterium tuberculosis and Mycobacterium leprae survive by making them penicillin resistant.
Collapse
Affiliation(s)
- Colette Goffin
- Center for Protein Engineering, Institut de Chimie, University of Liège, B-4000 Sart Tilman, Liège, Belgium
| | | |
Collapse
|
34
|
Stancik LM, Stancik DM, Schmidt B, Barnhart DM, Yoncheva YN, Slonczewski JL. pH-dependent expression of periplasmic proteins and amino acid catabolism in Escherichia coli. J Bacteriol 2002; 184:4246-58. [PMID: 12107143 PMCID: PMC135203 DOI: 10.1128/jb.184.15.4246-4258.2002] [Citation(s) in RCA: 235] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Escherichia coli grows over a wide range of pHs (pH 4.4 to 9.2), and its own metabolism shifts the external pH toward either extreme, depending on available nutrients and electron acceptors. Responses to pH values across the growth range were examined through two-dimensional electrophoresis (2-D gels) of the proteome and through lac gene fusions. Strain W3110 was grown to early log phase in complex broth buffered at pH 4.9, 6.0, 8.0, or 9.1. 2-D gel analysis revealed the pH dependence of 19 proteins not previously known to be pH dependent. At low pH, several acetate-induced proteins were elevated (LuxS, Tpx, and YfiD), whereas acetate-repressed proteins were lowered (Pta, TnaA, DksA, AroK, and MalE). These responses could be mediated by the reuptake of acetate driven by changes in pH. The amplified proton gradient could also be responsible for the acid induction of the tricarboxylic acid (TCA) enzymes SucB and SucC. In addition to the autoinducer LuxS, low pH induced another potential autoinducer component, the LuxH homolog RibB. pH modulated the expression of several periplasmic and outer membrane proteins: acid induced YcdO and YdiY; base induced OmpA, MalE, and YceI; and either acid or base induced OmpX relative to pH 7. Two pH-dependent periplasmic proteins were redox modulators: Tpx (acid-induced) and DsbA (base-induced). The locus alx, induced in extreme base, was identified as ygjT, whose product is a putative membrane-bound redox modulator. The cytoplasmic superoxide stress protein SodB was induced by acid, possibly in response to increased iron solubility. High pH induced amino acid metabolic enzymes (TnaA and CysK) as well as lac fusions to the genes encoding AstD and GabT. These enzymes participate in arginine and glutamate catabolic pathways that channel carbon into acids instead of producing alkaline amines. Overall, these data are consistent with a model in which E. coli modulates multiple transporters and pathways of amino acid consumption so as to minimize the shift of its external pH toward either acidic or alkaline extreme.
Collapse
|
35
|
Pease AJ, Roa BR, Luo W, Winkler ME. Positive growth rate-dependent regulation of the pdxA, ksgA, and pdxB genes of Escherichia coli K-12. J Bacteriol 2002; 184:1359-69. [PMID: 11844765 PMCID: PMC134838 DOI: 10.1128/jb.184.5.1359-1369.2002] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We found that transcription of the pdxA and pdxB genes, which mediate steps in the biosynthesis of the essential coenzyme pyridoxal 5"-phosphate, and the ksgA gene, which encodes an rRNA modification enzyme and is partly cotranscribed with pdxA, is subject to positive growth rate regulation in Escherichia coli K-12. The amounts of the pdxA-ksgA cotranscript and pdxB- and ksgA-specific transcripts and expression from pdxA- and pdxB-lacZ fusions increased as the growth rate increased. The half-lives of ksgA- and pdxB-specific transcripts were not affected by the growth rate, whereas the half-life of the pdxA-ksgA cotranscript was too short to be measured accurately. A method of normalization was applied to determine the amount of mRNA synthesized per gene and the rate of protein accumulation per gene. Normalization removed an apparent anomaly at fast growth rates and demonstrated that positive regulation of pdxB occurs at the level of transcription initiation over the whole range of growth rates tested. RNA polymerase limitation and autoregulation could not account for the positive growth rate regulation of pdxA, pdxB, and ksgA transcription. On the other hand, growth rate regulation of the amount of the pdxA-ksgA cotranscript was abolished by a fis mutation, suggesting a role for the Fis protein. In contrast, the fis mutation had no effect on pdxB- or ksgA-specific transcript amounts. The amounts of the pdxA-ksgA cotranscript and ksgA-specific transcript were repressed in the presence of high intracellular concentrations of guanosine tetraphosphate; however, this effect was independent of relA function for the pdxA-ksgA cotranscript. Amounts of the pdxB-specific transcript remained unchanged during amino acid starvation in wild-type and relA mutant strains.
Collapse
Affiliation(s)
- Andrew J Pease
- Department of Microbiology and Molecular Genetics, University of Texas Houston Medical School, Houston, TX 77030-1501, USA
| | | | | | | |
Collapse
|
36
|
Testerman TL, Vazquez-Torres A, Xu Y, Jones-Carson J, Libby SJ, Fang FC. The alternative sigma factor sigmaE controls antioxidant defences required for Salmonella virulence and stationary-phase survival. Mol Microbiol 2002; 43:771-82. [PMID: 11929531 DOI: 10.1046/j.1365-2958.2002.02787.x] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bacteria must contend with conditions of nutrient limitation in all natural environments. Complex programmes of gene expression, controlled in part by the alternative sigma factors sigmaS (sigma38, RpoS) and sigmaH (sigma32, RpoH), allow a number of bacterial species to survive conditions of partial or complete starvation. We show here that the alternative sigma factor sigmaE (sigma24, RpoE) also facilitates the survival of Salmonella typhimurium under conditions of nutrient deprivation. Expression of the sigmaE regulon is strongly induced upon entry of Salmonella into stationary phase. A Salmonella mutant lacking sigmaE has reduced survival during stationary phase as well as increased susceptibility to oxidative stress. A Salmonella strain lacking both sigmaE and sigmaS is non-viable after just 24 h in stationary phase, but survival of these mutants is completely preserved under anaerobic stationary-phase conditions, suggesting that oxidative injury is one of the major mechanisms of reduced microbial viability during periods of nutrient deprivation. Moreover, the attenuated virulence of sigmaE-deficient Salmonella for mice can be largely restored by genetic abrogation of the host phagocyte respiratory burst, suggesting that the sigmaE regulon plays an important antioxidant role during Salmonella infection of mammalian hosts.
Collapse
Affiliation(s)
- Traci L Testerman
- Department of Medicine, University of Colorado Health Sciences Center, Denver, CO 80262, USA
| | | | | | | | | | | |
Collapse
|
37
|
Webb HM, Ruddock LW, Marchant RJ, Jonas K, Klappa P. Interaction of the periplasmic peptidylprolyl cis-trans isomerase SurA with model peptides. The N-terminal region of SurA id essential and sufficient for peptide binding. J Biol Chem 2001; 276:45622-7. [PMID: 11546789 DOI: 10.1074/jbc.m107508200] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
One of the rate-limiting steps in protein folding has been shown to be the cis-trans isomerization of proline residues, which is catalyzed by a range of peptidylprolyl cis-trans isomerases. To characterize the interaction between model peptides and the periplasmic peptidylprolyl cis-trans isomerase SurA from E. coli, we employed a chemical cross-linking strategy that has been used previously to elucidate the interaction of substrates with other folding catalysts. The interaction between purified SurA and model peptides was significant in that it showed saturation and was abolished by denaturation of SurA; however the interaction was independent of the presence of proline residues in the model peptides. From results obtained by limited proteolysis we conclude that an N-terminal fragment of SurA, comprising 150 amino acids that do not contain the active sites involved in the peptidylprolyl cis-trans isomerization, is essential for the binding of peptides by SurA. This was confirmed by probing the interaction of the model peptide with the recombinant N-terminal fragment, expressed in Escherichia coli. Hence we propose that, similar to protein disulfide isomerase and other folding catalysts, SurA exhibits a modular architecture composed of a substrate binding domain and distinct catalytically active domains.
Collapse
Affiliation(s)
- H M Webb
- University of Kent, Canterbury CT2 7NJ, United Kingdom
| | | | | | | | | |
Collapse
|
38
|
Rizzitello AE, Harper JR, Silhavy TJ. Genetic evidence for parallel pathways of chaperone activity in the periplasm of Escherichia coli. J Bacteriol 2001; 183:6794-800. [PMID: 11698367 PMCID: PMC95519 DOI: 10.1128/jb.183.23.6794-6800.2001] [Citation(s) in RCA: 199] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The periplasm of Escherichia coli contains many proteins proposed to have redundant functions in protein folding. Using depletion analysis, we directly demonstrated that null mutations in skp and surA, as well as in degP and surA, result in synthetic phenotypes, suggesting that Skp, SurA, and DegP are functionally redundant. The Deltaskp surA::kan combination has a bacteriostatic effect and leads to filamentation, while the degP::Tn10 surA::kan combination is bactericidal. The steady-state levels of several envelope proteins are greatly reduced upon depletion of a wild-type copy of surA in both instances. We suggest that the functional redundancy of Skp, SurA, and DegP lies in the periplasmic chaperone activity. Taken together, our data support a model in which the periplasm of E. coli contains parallel pathways for chaperone activity. In particular, we propose that Skp and DegP are components of the same pathway and that SurA is a component of a separate pathway. The loss of either pathway has minimal effects on the cell, while the loss of both pathways results in the synthetic phenotypes observed.
Collapse
Affiliation(s)
- A E Rizzitello
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| | | | | |
Collapse
|
39
|
Fukuda T, Nakahigashi K, Inokuchi H. Viability of escherichia coli cells under long-term cultivation in a rich nutrient medium. Genes Genet Syst 2001; 76:271-8. [PMID: 11817642 DOI: 10.1266/ggs.76.271] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We investigated the viability of Escherichia coli cells during long-term cultivation in Brain Heart Infusion (BHI) medium and observed that the number of viable cells increased, then decreased, and increased again, in this medium, and finally the cells died out within about 10 days. This cell death may result from an increase in the pH of the medium. After repeated cultivation in BHI, bacterial cells that did not die out even under conditions of further cultivation were obtainable from cultures showing a stabilized viable count. We propose that long-term cultivation in BHI medium is a good system for studying growth phase-specific events in E. coli cells, because the total life-cycle of a population of E. coli, including exponential growth, stationary phase, and extinction, can be seen during a period of only about 10 days. Also, this system clearly allows detection of a phenotype that may not be detectable in other commonly used media. Moreover, in this report, we show that mutants displaying the GASP (growth advantage in stationary phase) phenotype appear at high frequency under long-term cultivation conditions.
Collapse
Affiliation(s)
- T Fukuda
- Department of Biophysics, Graduate School of Science, Kyoto University, Japan
| | | | | |
Collapse
|
40
|
Matsuzaki M, Kiso Y, Yamamoto I, Satoh T. Gene disruption analysis of DppA isolated as a periplasmic molecular chaperone-like protein for folding of dimethyl sulfoxide reductase in Rhodobacter sphaeroides f. sp. denitrificans. FEMS Microbiol Lett 2000; 193:223-9. [PMID: 11111028 DOI: 10.1111/j.1574-6968.2000.tb09428.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
The effect of inactivation of DppA, a dipeptide transport protein identified as a periplasmic molecular chaperone-like protein, on the formation of active dimethyl sulfoxide reductase (DMSOR) was examined in Rhodobacter sphaeroides f. sp. denitrificans. All of the dppA-disrupted mutants produced a normal level of native form of DMSOR and grew by DMSO respiration, indicating that the loss of DppA protein alone had no effect on the formation of active DMSOR. The periplasmic fraction of the dppA-disrupted mutant also had the activity to prevent aggregation of acid-unfolded DMSOR. Two proteins, DctP and BztA, were further identified as the proteins with the activity. Their activities, however, were much lower than that of DppA. These results suggest that several substrate binding proteins might be implicated in the folding of unfolded DMSOR in the periplasm.
Collapse
Affiliation(s)
- M Matsuzaki
- Department of Biological Science, Graduate School of Science, Hiroshima University, Kagamiyama 1-3-1, 739-8526, Higashi-Hiroshima, Japan
| | | | | | | |
Collapse
|
41
|
Keer J, Smeulders MJ, Gray KM, Williams HD. Mutants of Mycobacterium smegmatis impaired in stationary-phase survival. MICROBIOLOGY (READING, ENGLAND) 2000; 146 ( Pt 9):2209-2217. [PMID: 10974108 DOI: 10.1099/00221287-146-9-2209] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A bank of 600 insertional mutants of Mycobacterium smegmatis was screened for mutants defective in stationary-phase survival. Of 74 mutants picked by the initial screen, 21 had stationary-phase survival defects and 7 of these were studied in more detail. In general, mutants survived stationary phase significantly less well in rich medium than under carbon-starvation conditions. In all cases the loss of viability in stationary phase was not complete even after prolonged incubation. All mutants showed an initial decrease in viability, during the first 40 d in stationary phase, followed by an increase in viable counts that returned viability close to the levels of the wild-type. Southern hybridization experiments showed that recovery of viability was not a consequence of precise excision or movement of the transposon. Two of the survival mutants differed from the wild-type in their colony morphology, and recovery of their viability in stationary phase was coincident with the return of wild-type colony morphology. It is possible that second-site suppressor mutations accumulate that alleviate the effects of the original mutation. For five of the mutants the DNA flanking the site of transposition was amplified by ligation-mediated PCR and sequenced to identify the disrupted locus. In each case, homologous genes were identified in the Mycobacterium tuberculosis genome, three of which have clearly predicted functions in M. tuberculosis as a penicillin-binding protein, in biotin biosynthesis and as a polyketide synthase. This is the first identification of genes implicated in the stationary-phase survival of mycobacteria.
Collapse
Affiliation(s)
- Jacquie Keer
- Department of Biology, Imperial College of Science, Technology and Medicine, Imperial College Road, London SW7 2AZ, UK1
| | - Marjan J Smeulders
- Department of Biology, Imperial College of Science, Technology and Medicine, Imperial College Road, London SW7 2AZ, UK1
| | - Kathryn M Gray
- Department of Biology, Imperial College of Science, Technology and Medicine, Imperial College Road, London SW7 2AZ, UK1
| | - Huw D Williams
- Department of Biology, Imperial College of Science, Technology and Medicine, Imperial College Road, London SW7 2AZ, UK1
| |
Collapse
|
42
|
Sydenham M, Douce G, Bowe F, Ahmed S, Chatfield S, Dougan G. Salmonella enterica serovar typhimurium surA mutants are attenuated and effective live oral vaccines. Infect Immun 2000; 68:1109-15. [PMID: 10678914 PMCID: PMC97255 DOI: 10.1128/iai.68.3.1109-1115.2000] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A previously described attenuated TnphoA mutant (BRD441) of Salmonella enterica serovar Typhimurium C5 (I. Miller, D. Maskell, C. Hormaeche, K. Johnson, D. Pickard, and G. Dougan, Infect. Immun. 57:2758-2763, 1989) was characterized, and the transposon was shown to be inserted in surA, a gene which encodes a peptidylprolyl-cis, trans-isomerase. A defined surA deletion mutation was introduced into S. enterica serovar Typhimurium C5 and the mutant strain, named S. enterica serovar Typhimurium BRD1115, was extensively characterized both in vitro and in vivo. S. enterica serovar Typhimurium BRD1115 was found to be defective in the ability to adhere to and invade eukaryotic cells. Furthermore, S. enterica serovar Typhimurium BRD1115 was attenuated by at least 3 log units when administered orally or intravenously to BALB/c mice. Complementation of the mutation with a plasmid carrying the intact surA gene almost completely restored the virulence of BRD1115. In addition, S. enterica serovar Typhimurium BRD1115 demonstrated potential as a vaccine candidate, since mice immunized with BRD1115 were protected against subsequent challenge with S. enterica serovar Typhimurium C5. S. enterica serovar Typhimurium BRD1115 also showed potential as a vehicle for the effective delivery of heterologous antigens, such as the nontoxic, protective fragment C domain of tetanus toxin, to the murine immune system.
Collapse
Affiliation(s)
- M Sydenham
- Medeva Vaccine Development Group, Department of Biochemistry, Imperial College of Science, Technology and Medicine, London SW7 2AZ, United Kingdom
| | | | | | | | | | | |
Collapse
|
43
|
Vasi FK, Lenski RE. Ecological strategies and fitness tradeoffs inEscherichia coli mutants adapted to prolonged starvation. J Genet 1999. [DOI: 10.1007/bf02994702] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
44
|
Abstract
Inducible tolerance to acidic and alkaline environments is recognized as an important survival strategy for many prokaryotic and eukaryotic microorganisms. Recent developments in understanding this phenomenon include the identification of regulatory genes, specific tolerance mechanisms and genes associated with tolerance. In addition, there is significant evidence linking pH responses with virulence.
Collapse
Affiliation(s)
- J W Foster
- Department of Microbiology and Immunology, University of South Alabama, College of Medicine, Mobile, AL 36688, USA.
| |
Collapse
|
45
|
Blankenhorn D, Phillips J, Slonczewski JL. Acid- and base-induced proteins during aerobic and anaerobic growth of Escherichia coli revealed by two-dimensional gel electrophoresis. J Bacteriol 1999; 181:2209-16. [PMID: 10094700 PMCID: PMC93635 DOI: 10.1128/jb.181.7.2209-2216.1999] [Citation(s) in RCA: 167] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Proteins induced by acid or base, during long-term aerobic or anaerobic growth in complex medium, were identified in Escherichia coli. Two-dimensional gel electrophoresis revealed pH-dependent induction of 18 proteins, nine of which were identified by N-terminal sequencing. At pH 9, tryptophan deaminase (TnaA) was induced to a high level, becoming one of the most abundant proteins observed. TnaA may reverse alkalinization by metabolizing amino acids to produce acidic products. Also induced at high pH, but only in anaerobiosis, was glutamate decarboxylase (GadA). The gad system (GadA/GadBC) neutralizes acidity and enhances survival in extreme acid; its induction during anaerobic growth may help protect alkaline-grown cells from the acidification resulting from anaerobic fermentation. To investigate possible responses to internal acidification, cultures were grown in propionate, a membrane-permeant weak acid which acidifies the cytoplasm. YfiD, a homologue of pyruvate formate lyase, was induced to high levels at pH 4.4 and induced twofold more by propionate at pH 6; both of these conditions cause internal acidification. At neutral or alkaline pH, YfiD was virtually absent. YfiD is therefore a strong candidate for response to internal acidification. Acid or propionate also increased the expression of alkyl hydroperoxide reductase (AhpC) but only during aerobic growth. At neutral or high pH, AhpC showed no significant difference between aerobic and anaerobic growth. The increase of AhpC in acid may help protect the cell from the greater concentrations of oxidizing intermediates at low pH. Isocitrate lyase (AceA) was induced by oxygen across the pH range but showed substantially greater induction in acid or in base than at pH 7. Additional responses observed included the induction of MalE at high pH and induction of several enzymes of sugar metabolism at low pH: the phosphotransferase system components ManX and PtsH and the galactitol fermentation enzyme GatY. Overall, our results indicate complex relationships between pH and oxygen and a novel permeant acid-inducible gene, YfiD.
Collapse
Affiliation(s)
- D Blankenhorn
- Department of Biology, Kenyon College, Gambier, Ohio 43022, USA
| | | | | |
Collapse
|