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Abstract
The stressosome co-ordinates the response of Bacillus subtilis to the imposition of a variety of physical and environmental insults. These stresses include fluctuations in salt concentration, the presence of ethanol, changes in pH and even the level of UV light. Despite the obvious and significant differences between these quite different physicochemical stimuli, the result is the same: the stressosome is phosphorylated by a key kinase to initiate the sigma(B) cascade. The phosphorylation of the stressosome initiates a signal transduction system that up-regulates the expression of stress-responsive genes so that the Bacillus can survive the imposition of stress. Hence the stressosome acts as a hub, receiving manifold different stimuli to effect a single outcome. Using single-particle analysis of cryo-electron micrographs, we have been able to reconstruct a series of molecular envelopes of the stressosome. These maps have been interpreted at near-atomic resolution with crystal structures of the individual components of the stressosome to provide the first visualization of this unique signalling hub. The macromolecular structure adopted by the stressosome provides the signalling cascade with the potential for co-operative behaviour, which we have also measured in live bacteria. These experiments are consistent with the tuning of the response of B. subtilis to stress relative to the magnitude of the insult.
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52
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de Been M, Francke C, Siezen RJ, Abee T. Novel sigmaB regulation modules of Gram-positive bacteria involve the use of complex hybrid histidine kinases. MICROBIOLOGY-SGM 2010; 157:3-12. [PMID: 21051490 DOI: 10.1099/mic.0.045740-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A common bacterial strategy to cope with stressful conditions is the activation of alternative sigma factors that control specific regulons enabling targeted responses. In the human pathogen Bacillus cereus, activation of the major stress-responsive sigma factor σ(B) is controlled by a signalling route that involves the multi-sensor hybrid histidine kinase RsbK. RsbK-type kinases are not restricted to the B. cereus group, but occur in a wide variety of other bacterial species, including members of the the low-GC Gram-positive genera Geobacillus and Paenibacillus as well as the high-GC actinobacteria. Genome context and protein sequence analyses of 118 RsbK homologues revealed extreme variability in N-terminal sensory as well as C-terminal regulatory domains and suggested that RsbK-type kinases are subject to complex fine-tuning systems, including sensitization and desensitization via methylation and demethylation within the helical domain preceding the H-box. The RsbK-mediated stress-responsive sigma factor activation mechanism that has evolved in B. cereus and the other species differs markedly from the extensively studied and highly conserved RsbRST-mediated σ(B) activation route found in Bacillus subtilis and other low-GC Gram-positive bacteria. Implications for future research on sigma factor control mechanisms are presented and current knowledge gaps are briefly discussed.
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Affiliation(s)
- Mark de Been
- Faculty of Veterinary Medicine, Department of Veterinary Biosciences, Veterinary Microbiology and Epidemiology, University of Helsinki, Helsinki, Finland.,TI Food and Nutrition (TIFN), Wageningen, The Netherlands.,Laboratory of Food Microbiology, Wageningen University and Research Centre, Wageningen, The Netherlands.,Centre for Molecular and Biomolecular Informatics (CMBI), NCMLS, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Christof Francke
- TI Food and Nutrition (TIFN), Wageningen, The Netherlands.,Centre for Molecular and Biomolecular Informatics (CMBI), NCMLS, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Roland J Siezen
- NIZO food research BV, Ede, The Netherlands.,TI Food and Nutrition (TIFN), Wageningen, The Netherlands.,Centre for Molecular and Biomolecular Informatics (CMBI), NCMLS, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Tjakko Abee
- TI Food and Nutrition (TIFN), Wageningen, The Netherlands.,Laboratory of Food Microbiology, Wageningen University and Research Centre, Wageningen, The Netherlands
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53
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Stressosomes formed in Bacillus subtilis from the RsbR protein of Listeria monocytogenes allow σ(B) activation following exposure to either physical or nutritional stress. J Bacteriol 2010; 192:6279-86. [PMID: 20935101 DOI: 10.1128/jb.00467-10] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
The general stress regulon of Bacillus subtilis is controlled by σ(B), a transcription factor that is activated by physical or nutritional stress. In B. subtilis, each of these two stresses is communicated to the primary σ(B) regulators by distinct pathways. Physical stress activation of σ(B) involves a large-molecular-mass (>10(6)-Da) structure (stressosome) formed by one or more homologous proteins (RsbRA, -B, -C, and -D) onto which the pathway's principal regulators are bound. The RsbR proteins are thought to be potential receptors for stress signaling. Listeria monocytogenes encodes orthologs of σ(B) and its principal regulators; however, unlike B. subtilis, L. monocytogenes appears to use the stressosome pathway for both physical and nutritional stress activation of σ(B). In the current work, a B. subtilis strain that expressed L. monocytogenes rsbR (rsbR(Lm)) in lieu of B. subtilis rsbR (rsbR(Bs)) was created and was found to display the Listeria phenotype of σ(B) activation following exposure to either physical or nutritional stress. B. subtilis expressing either the RsbR paralog rsbRC or rsbRD, but not rsbRA or rsbRB, as the sole source of RsbR also allowed σ(B) induction following nutritional stress. It is unclear whether the nutritional stress induction seen in these strains is the result of a direct effect of nutritional stress on stressosome activity or a consequence of the background levels of σ(B) activation in these strains and the effects of diminished ATP on the downstream phosphorylation reaction needed to reinactivate σ(B).
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Aínsa JA, Bird N, Ryding NJ, Findlay KC, Chater KF. The complex whiJ locus mediates environmentally sensitive repression of development of Streptomyces coelicolor A3(2). Antonie van Leeuwenhoek 2010; 98:225-36. [PMID: 20405209 DOI: 10.1007/s10482-010-9443-3] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2010] [Accepted: 04/01/2010] [Indexed: 11/27/2022]
Abstract
A segment of DNA was isolated that complemented several poorly characterised sporulation-defective white-colony mutants of Streptomyces coelicolor A3(2) from an early collection (Hopwood et al., J Gen Microbiol 61: 397-408, 1970). Complementation was attributable to a gene, SCO4543, named whiJ, encoding a likely DNA-binding protein. Surprisingly, although some mutations in whiJ had a white colony phenotype, complete deletion of the wild-type or mutant gene gave a wild-type morphology. The whiJ gene is a member of a large paralogous set of S. coelicolor genes including abaAorfA, which regulates antibiotic production; and genes flanking whiJ are paralogues of other gene classes that are often associated with whiJ-like genes (Gehring et al., Proc Natl Acad Sci USA 97: 9642-9647, 2000). Thus, the small gene SCO4542 encodes a paralogue of the abaAorfD gene product, and SCO4544 encodes a paralogue of a family of likely anti-sigma factors (including the product of abaAorfB). Deletion of SCO4542 resulted in a medium-dependent bald- or white-colony phenotype, which could be completely suppressed by the simultaneous deletion of whiJ. A model is proposed in which WhiJ binds to operator sequences to repress developmental genes, with repression being released by interaction with the WhiJ-associated SCO4542 protein. It is suggested that this activity of SCO4542 protein is prevented by an unknown signal.
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Affiliation(s)
- José A Aínsa
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Colney, Norwich NR4 7UH, UK
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55
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Phosphorylation of MgrA and its effect on expression of the NorA and NorB efflux pumps of Staphylococcus aureus. J Bacteriol 2010; 192:2525-34. [PMID: 20233929 DOI: 10.1128/jb.00018-10] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
MgrA is a global regulator in Staphylococcus aureus that controls the expression of diverse genes encoding virulence factors and multidrug resistance (MDR) efflux transporters. We identified pknB, which encodes the (Ser/Thr) kinase PknB, in the S. aureus genome. PknB was able to autophosphorylate as well as phosphorylate purified MgrA. We demonstrated that rsbU, which encodes a Ser/Thr phosphatase and is involved in the activation of the SigB regulon, was able to dephosphorylate MgrA-P but not PknB-P. Serines 110 and 113 of MgrA were found to be phosphorylated, and Ala substitutions at these positions resulted in reductions in the level of phosphorylation of MgrA. DNA gel shift binding assays using norA and norB promoters showed that MgrA-P was able to bind the norB promoter but not the norA promoter, a pattern which was the reverse of that for unphosphorylated MgrA. The double mutant MgrA(S110A-S113A) bound to the norA promoter but not the norB promoter. The double mutant led to a 2-fold decrease in norA transcripts and a 2-fold decrease in the MICs of norfloxacin and ciprofloxacin in strain RN6390. Thus, phosphorylation of MgrA results in loss of binding to the norA promoter, but with a gain of the ability to bind the norB promoter. Loss of the ability to phosphorylate MgrA by Ala substitution resulted in increased repression of norA expression and in reductions in susceptibilities to NorA substrates.
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56
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Reeves A, Martinez L, Haldenwang W. Expression of, and in vivo stressosome formation by, single members of the RsbR protein family in Bacillus subtilis. MICROBIOLOGY-SGM 2009; 156:990-998. [PMID: 20019076 DOI: 10.1099/mic.0.036095-0] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The Bacillus subtilis stressosome is a 1.8 MDa complex that is the focal point for activating the bacterium's general response to physical stress. In vitro studies demonstrated that the stressosome's core element can be formed from one or more of a family of paralogous proteins (RsbRA, -RB, -RC and -RD) onto which the system's activator protein (RsbT) and its principal inhibitor (RsbS) are bound. The RsbR components of the stressosome are envisioned to be the initial receptors of stress signalling with the stressosome structure itself serving as a device to integrate multiple stress signals for a coordinated response. In the current work, we examine several of the in vivo characteristics of the RsbR family members, including their expression and ability to form stressosomes to regulate sigma(B). Translational fusions of lacZ to each rsbR paralogue revealed that rsbRA, -RB and -RC are expressed at similar levels, which remain relatively constant during growth, ethanol stress and entry into stationary phase. rsbRD, in contrast, is expressed at a level that is only slightly above background during growth, but is induced to 30 % of the rsbRA expression level following ethanol stress. Velocity sedimentation analyses of B. subtilis extracts from strains expressing single rsbR paralogues demonstrated that each incorporates RsbS into fast-sedimenting complexes. However, consistent with rsbRD's lower expression, the RsbRD-dependent RsbS complexes were present at only 20 % of the level of the complexes seen in a wild-type strain. The lower stressosome level in the RsbRD strain is still able to hold RsbT's activity in check, implying that the RsbR/S component of stressosomes is normally in excess for the control of RsbT. Consistent with such a notion, reporter gene and Western blot assays demonstrate that although RsbT is synthesized at the same rate as RsbRA and RsbS, RsbT's ultimate level in growing B. subtilis is only 10 % that of RsbRA. Apparently, RsbT's inherent structure and/or its passage between the stressosome and its activation target compromises its persistence.
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Affiliation(s)
- Adam Reeves
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
| | - Luis Martinez
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
| | - William Haldenwang
- Department of Microbiology and Immunology, The University of Texas Health Science Center at San Antonio, San Antonio, TX 78229-3900, USA
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57
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de Been M, Tempelaars MH, van Schaik W, Moezelaar R, Siezen RJ, Abee T. A novel hybrid kinase is essential for regulating the sigma(B)-mediated stress response of Bacillus cereus. Environ Microbiol 2009; 12:730-45. [PMID: 19958380 DOI: 10.1111/j.1462-2920.2009.02116.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A common bacterial strategy for monitoring environmental challenges is to use two-component systems, which consist of a sensor histidine kinase (HK) and a response regulator (RR). In the food-borne pathogen Bacillus cereus, the alternative sigma factor sigma(B) is activated by the RR RsbY. Here we present strong indications that the PP2C-type phosphatase RsbY receives its input from the multi-sensor hybrid kinase BC1008 (renamed RsbK). Genome analyses revealed that, across bacilli, rsbY and rsbK are located in a conserved gene cluster. A B. cereus rsbK deletion strain was shown to be incapable of inducing sigma(B) upon stress conditions and was impaired in its heat adaptive response. Comparison of the wild-type and rsbK mutant transcriptomes upon heat shock revealed that RsbK was primarily involved in the activation of the sigma(B)-mediated stress response. Truncation of the RsbK RR receiver domain demonstrated the importance of this domain for sigma(B) induction upon stress. The domain architecture of RsbK suggests that in the B. cereus group and in other bacilli, environmental and intracellular stress signalling routes are combined into one single protein. This strategy is markedly different from the sigma(B) activation pathway in other low-GC Gram-positives.
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Affiliation(s)
- Mark de Been
- TI Food and Nutrition (TIFN), Wageningen, the Netherlands.
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58
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Suganuma M, Teh AH, Makino M, Shimizu N, Kaneko T, Hirata K, Yamamoto M, Kumasaka T. Crystallization and preliminary X-ray analysis of the stress-response PPM phosphatase RsbX from Bacillus subtilis. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:1128-30. [PMID: 19923733 PMCID: PMC2777041 DOI: 10.1107/s1744309109038846] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2009] [Accepted: 09/25/2009] [Indexed: 11/10/2022]
Abstract
RsbX from Bacillus subtilis is a manganese-dependent PPM phosphatase and negatively regulates the signal transduction of the general stress response by the dephosphorylation of RsbS and RsbR, which are activators of the alternative RNA polymerase sigma factor SigB. In order to elucidate the structural-functional relationship of its Ser/Thr protein-phosphorylation mechanism, an X-ray crystallographic diffraction study of RsbX was performed. Recombinant RsbX was expressed in Escherichia coli, purified and crystallized. Crystals were obtained using the sitting-drop vapour-diffusion method and X-ray diffraction data were collected to 1.06 angstrom resolution with an R(merge) of 8.1%. The crystals belonged to the triclinic space group P1, with unit-cell parameters a = 33.3, b = 41.7, c = 68.6 angstrom , alpha = 98.8, beta = 90.0, gamma = 108.4 degrees.
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Affiliation(s)
| | - Aik Hong Teh
- Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), Japan
| | - Masatomo Makino
- Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), Japan
| | - Nobutaka Shimizu
- Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), Japan
| | - Tomonori Kaneko
- Department of Life Science, Tokyo Institute of Technology, Japan
| | | | | | - Takashi Kumasaka
- Japan Synchrotron Radiation Research Institute (SPring-8/JASRI), Japan
- RIKEN SPring-8 Center, Japan
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59
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Greenstein AE, Hammel M, Cavazos A, Alber T. Interdomain communication in the Mycobacterium tuberculosis environmental phosphatase Rv1364c. J Biol Chem 2009; 284:29828-35. [PMID: 19700407 DOI: 10.1074/jbc.m109.056168] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
An "environmental phosphatase" controls bacterial transcriptional responses through alternative sigma factor subunits of RNA polymerase and a partner switching mechanism has been proposed to mediate phosphatase regulation. In many bacteria, the environmental phosphatase and multiple regulators are encoded in separate genes whose products form transient complexes. In contrast, in the Mycobacterium tuberculosis homolog, Rv1364c, the phosphatase is fused to two characteristic regulatory modules with sequence similarities to anti-sigma factor kinases and anti-anti-sigma factor proteins. Here we exploit this fusion to explore interactions between the phosphatase and the regulatory domains. We show quantitatively that the anti-sigma factor kinase domain activates the phosphatase domain, the kinase-phosphatase fusion protein autophosphorylates in Escherichia coli, and phosphorylation is antagonized by the phosphatase activity. Small angle x-ray scattering defines solution structures consistent with the interdomain communication observed biochemically. Taken together, these data indicate that Rv1364c provides a single chain framework to understand the structure, function, and regulation of environmental phosphatases throughout the bacterial kingdom.
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Affiliation(s)
- Andrew E Greenstein
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3220, USA
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60
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orf4 of the Bacillus cereus sigB gene cluster encodes a general stress-inducible Dps-like bacterioferritin. J Bacteriol 2009; 191:4522-33. [PMID: 19429618 DOI: 10.1128/jb.00272-09] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The function of orf4 in the sigB cluster in Bacillus cereus ATCC 14579 remains to be explored. Amino-acid sequence analysis has revealed that Orf4 is homologous with bacterioferritins and Dps. In this study, we generated an orf4-null mutant and produced recombinant protein rOrf4 to establish the role of orf4. In vitro, the purified rOrf4 was found to exist in two distinct forms, a dimeric form and a polymer form, through size exclusion analysis. The latter form exhibited a unique filament structure, in contrast to the typical spherical tetracosamer structure of bacterioferritins; the former can be induced to form rOrf4 polymers immediately after the addition of FeCl(2). Catalysis of the oxidation of ferrous irons by ferroxidase activity was detected with rOrf4, and the mineralized irons were subsequently sequestered only in the rOrf4 polymer. Moreover, rOrf4 exerted DNA-protective activity against oxidative damage via DNA binding in a nonspecific manner, as is seen with Dps. In vivo, deletion of orf4 had no effect on activation of the alternative sigma factor sigma(B), and therefore, orf4 is not associated with sigma(B) regulation; however, orf4 can be significantly upregulated upon environmental stress but not H(2)O(2) treatment. B. cereus strains with constitutive Orf4 expression exhibited a viability higher than that of the orf4-null mutant, under specific oxidative stress or heat shock. Taken together, these results suggest that Orf4 functions as a Dps-like bacterioferritin in response to environmental stress and can provide cell protection from oxidative damage through iron sequestration and DNA binding.
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61
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Hecker M, Reder A, Fuchs S, Pagels M, Engelmann S. Physiological proteomics and stress/starvation responses in Bacillus subtilis and Staphylococcus aureus. Res Microbiol 2009; 160:245-58. [PMID: 19403106 DOI: 10.1016/j.resmic.2009.03.008] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2009] [Revised: 03/20/2009] [Accepted: 03/23/2009] [Indexed: 10/20/2022]
Abstract
Gel-based proteomics is a useful approach for visualizing the responses of bacteria to stress and starvation stimuli. In order to face stress/starvation, bacteria have developed very complicated gene expression networks. A proteomic view of stress/starvation responses, however, is only a starting point which should promote follow-up studies aimed at the comprehensive description of single regulons, their signal transduction pathways on the one hand, and their adaptive functions on the other, and finally their integration into complex gene expression networks. This "road map of physiological proteomics" will be demonstrated for the general stress regulon controlled by sigma(B) in Bacillus subtilis and the oxygen starvation response with Rex as a master regulator in Staphylococcus aureus.
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Affiliation(s)
- Michael Hecker
- Institute for Microbiology, Ernst-Moritz-Arndt-University Greifswald, Jahnstrasse 15A, 17487 Greifswald, Germany.
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62
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Pané-Farré J, Jonas B, Hardwick SW, Gronau K, Lewis RJ, Hecker M, Engelmann S. Role of RsbU in controlling SigB activity in Staphylococcus aureus following alkaline stress. J Bacteriol 2009; 191:2561-73. [PMID: 19201800 PMCID: PMC2668408 DOI: 10.1128/jb.01514-08] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2008] [Accepted: 01/28/2009] [Indexed: 02/04/2023] Open
Abstract
SigB is an alternative sigma factor that controls a large regulon in Staphylococcus aureus. Activation of SigB requires RsbU, a protein phosphatase 2C (PP2C)-type phosphatase. In a closely related organism, Bacillus subtilis, RsbU activity is stimulated upon interaction with RsbT, a kinase, which following an activating stimulus switches from a 25S high-molecular-weight complex, the stressosome, to the N-terminal domain of RsbU. Active RsbU dephosporylates RsbV and thereby triggers the release of SigB from its inhibitory complex with RsbW. While RsbU, RsbV, RsbW, and SigB are conserved in S. aureus, proteins similar to RsbT and the components of the stressosome are not, raising the question of how RsbU activity and hence SigB activity are controlled in S. aureus. We found that in contrast to the case in B. subtilis, the induced expression of RsbU was sufficient to stimulate SigB-dependent transcription in S. aureus. However, activation of SigB-dependent transcription following alkaline stress did not lead to a clear accumulation of SigB and its regulators RsbV and RsbW or to a change in the RsbV/RsbV-P ratio in S. aureus. When expressed in B. subtilis, the S. aureus RsbU displayed a high activity even in the absence of an inducing stimulus. This high activity could be transferred to the PP2C domain of the B. subtilis RsbU protein by a fusion to the N-terminal domain of the S. aureus RsbU. Collectively, the data suggest that the activity of the S. aureus RsbU and hence SigB may be subjected to different regulation in comparison to that in B. subtilis.
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Affiliation(s)
- Jan Pané-Farré
- Institut für Mikrobiologie, Ernst-Moritz-Arndt-Universität, F.-L.-Jahn-Str. 15, D-17487 Greifswald, Germany.
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63
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Marles-Wright J, Grant T, Delumeau O, van Duinen G, Firbank SJ, Lewis PJ, Murray JW, Newman JA, Quin MB, Race PR, Rohou A, Tichelaar W, van Heel M, Lewis RJ. Molecular Architecture of the "Stressosome," a Signal Integration and Transduction Hub. Science 2008; 322:92-6. [DOI: 10.1126/science.1159572] [Citation(s) in RCA: 130] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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64
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Quin M, Newman J, Firbank S, Lewis RJ, Marles-Wright J. Crystallization and preliminary X-ray analysis of RsbS from Moorella thermoacetica at 2.5 A resolution. Acta Crystallogr Sect F Struct Biol Cryst Commun 2008; 64:196-9. [PMID: 18323607 DOI: 10.1107/s1744309108003849] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2008] [Accepted: 02/05/2008] [Indexed: 01/18/2023]
Abstract
The thermophilic bacterium Moorella thermoacetica possesses an rsb operon that is related to the genetic locus common to many Gram-positive bacteria that regulates the activity of the stress-responsive sigma factor sigma(B). One of the gene products of this operon is RsbS, a single STAS-domain protein that is a component of higher order assemblies in Bacillus subtilis known as 'stressosomes'. It is expected that similar complexes are found in M. thermoacetica, but in this instance regulating the biosynthesis of cyclic di-GMP, a ubiquitous secondary messenger. Selenomethionine-labelled MtRsbS protein was crystallized at room temperature using the hanging-drop vapour-diffusion method. Crystals belonging to space group P2(1)2(1)2(1), with unit-cell parameters a = 51.07, b = 60.52, c = 89.28 A, diffracted to 2.5 A resolution on beamline I04 of the Diamond Light Source. The selenium substructure was solved using SHELX and it is believed that this represents the first reported ab initio crystal structure to be solved using diffraction data collected at DLS.
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Affiliation(s)
- Maureen Quin
- Structural Biology Laboratory, Institute for Cell and Molecular Biosciences, Medical School, Newcastle University, Newcastle upon Tyne NE2 4HH, England
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65
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Marles-Wright J, Lewis RJ. Stress responses of bacteria. Curr Opin Struct Biol 2007; 17:755-60. [DOI: 10.1016/j.sbi.2007.08.004] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Revised: 07/31/2007] [Accepted: 08/01/2007] [Indexed: 10/22/2022]
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66
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Ventura M, Canchaya C, Tauch A, Chandra G, Fitzgerald GF, Chater KF, van Sinderen D. Genomics of Actinobacteria: tracing the evolutionary history of an ancient phylum. Microbiol Mol Biol Rev 2007; 71:495-548. [PMID: 17804669 PMCID: PMC2168647 DOI: 10.1128/mmbr.00005-07] [Citation(s) in RCA: 597] [Impact Index Per Article: 35.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Actinobacteria constitute one of the largest phyla among bacteria and represent gram-positive bacteria with a high G+C content in their DNA. This bacterial group includes microorganisms exhibiting a wide spectrum of morphologies, from coccoid to fragmenting hyphal forms, as well as possessing highly variable physiological and metabolic properties. Furthermore, Actinobacteria members have adopted different lifestyles, and can be pathogens (e.g., Corynebacterium, Mycobacterium, Nocardia, Tropheryma, and Propionibacterium), soil inhabitants (Streptomyces), plant commensals (Leifsonia), or gastrointestinal commensals (Bifidobacterium). The divergence of Actinobacteria from other bacteria is ancient, making it impossible to identify the phylogenetically closest bacterial group to Actinobacteria. Genome sequence analysis has revolutionized every aspect of bacterial biology by enhancing the understanding of the genetics, physiology, and evolutionary development of bacteria. Various actinobacterial genomes have been sequenced, revealing a wide genomic heterogeneity probably as a reflection of their biodiversity. This review provides an account of the recent explosion of actinobacterial genomics data and an attempt to place this in a biological and evolutionary context.
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Affiliation(s)
- Marco Ventura
- Department of Genetics, Biology of Microorganisms, Anthropology and Evolution, University of Parma, parco Area delle Scienze 11a, 43100 Parma, Italy.
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67
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Eymann C, Becher D, Bernhardt J, Gronau K, Klutzny A, Hecker M. Dynamics of protein phosphorylation on Ser/Thr/Tyr inBacillus subtilis. Proteomics 2007; 7:3509-26. [PMID: 17726680 DOI: 10.1002/pmic.200700232] [Citation(s) in RCA: 75] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The Ser/Thr/Tyr phosphoproteome of Bacillus subtilis was analyzed by a 2-D gel-based approach combining Pro-Q Diamond staining and [(33)P]-labeling. In exponentially growing B. subtilis cells 27 proteins could be identified after staining with Pro-Q Diamond and/or [(33)P]-labeling and one additional protein was labeled solely by [(33)P] resulting in a total of 28 potentially phosphorylated proteins. These proteins are mainly involved in enzymatic reactions of basic carbon metabolism and the regulation of the alternative sigma factor sigma(B). We also found significant changes of the phosphoproteome including increased phosphorylation and dephosphorylation rates of some proteins as well as the detection of four newly phosphorylated proteins in response to stress or starvation. For nine proteins, phosphorylation sites at serine or threonine residues were determined by MS. These include the known phosphorylation sites of Crh, PtsH, and RsbV. Additionally, we were able to identify novel phosphorylation sites of AroA, Pyk, and YbbT. Interestingly, the phosphorylation of RsbRA, B, C, and D, four proteins of a multicomponent protein complex involved in environmental stress signaling, was found during exponential growth. For RsbRA, B, and D, phosphorylation of one of the conserved threonine residues in their C-termini were verified by MS (T171, T186, T181, respectively).
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Affiliation(s)
- Christine Eymann
- Institute for Microbiology, Ernst-Moritz-Arndt-University Greifswald, Greifswald, Germany
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68
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Reeves A, Gerth U, Völker U, Haldenwang WG. ClpP modulates the activity of the Bacillus subtilis stress response transcription factor, sigmaB. J Bacteriol 2007; 189:6168-75. [PMID: 17586624 PMCID: PMC1951893 DOI: 10.1128/jb.00756-07] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The general stress regulon of Bacillus subtilis is controlled by the activity state of sigmaB, a transcription factor that is switched on following exposure to either physical or nutritional stress. ClpP is the proteolytic component of an ATP-dependent protease that is essential for the proper regulation of multiple adaptive responses in B. subtilis. Among the proteins whose abundance increases in ClpP- B. subtilis are several known to depend on sigmaB for their expression. In the current work we examine the relationship of ClpP to the activity of sigmaB. The data reveal that the loss of ClpP in otherwise wild-type B. subtilis results in a small increase in sigmaB activity during growth and a marked enhancement of sigmaB activity following its induction by either physical or nutritional stress. It appears to be the persistence of sigmaB's activity rather than its induction that is principally affected by the loss of ClpP. sigmaB-dependent reporter gene activity rose in parallel in ClpP+ and ClpP- B. subtilis strains but failed to display its normal transience in the ClpP- strain. The putative ClpP targets are likely to be stress generated and novel. Enhanced sigmaB activity in ClpP- B. subtilis was triggered by physical stress but not by the induced synthesis of the physical stress pathway's positive regulator (RsbT). In addition, Western blot analyses failed to detect differences in the levels of the principal known sigmaB regulators in ClpP+ and ClpP- B. subtilis strains. The data suggest a model in which ClpP facilitates the turnover of stress-generated factors, which persist in ClpP's absence to stimulate ongoing sigmaB activity.
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Affiliation(s)
- Adam Reeves
- Department of Microbiology and Immunology, MC7758, University of Texas Health Science Center, 7703 Floyd Curl Dr., San Antonio, TX 78229-3900, USA
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69
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Greenstein AE, MacGurn JA, Baer CE, Falick AM, Cox JS, Alber T. M. tuberculosis Ser/Thr protein kinase D phosphorylates an anti-anti-sigma factor homolog. PLoS Pathog 2007; 3:e49. [PMID: 17411339 PMCID: PMC1847690 DOI: 10.1371/journal.ppat.0030049] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2006] [Accepted: 02/15/2007] [Indexed: 12/05/2022] Open
Abstract
Receptor Ser/Thr protein kinases are candidates for sensors that govern developmental changes and disease processes of Mycobacterium tuberculosis (Mtb), but the functions of these kinases are not established. Here, we show that Mtb protein kinase (Pkn) D overexpression alters transcription of numerous bacterial genes, including Rv0516c, a putative anti-anti–sigma factor, and genes regulated by sigma factor F. The PknD kinase domain directly phosphorylated Rv0516c, but no other sigma factor regulator, in vitro. In contrast, the purified PknB and PknE kinase domains phosphorylated distinct sigma regulators. Rather than modifying a consensus site, PknD phosphorylated Rv0516c in vitro and in vivo on Thr2 in a unique N-terminal extension. This phosphorylation inhibited Rv0516c binding in vitro to a homologous anti-anti–sigma factor, Rv2638. These results support a model in which signals transmitted through PknD alter the transcriptional program of Mtb by stimulating phosphorylation of a sigma factor regulator at an unprecedented control site. Many bacteria, including Mycobacterium tuberculosis (Mtb), sense the environment using a family of signaling proteins called Ser/Thr protein kinases (STPKs), but the functions of these sensors are not well understood. This study shows that the Mtb protein kinase (Pkn) D STPK attaches a phosphate group to one and only one member of a family of regulators of “alternative” sigma factors, which activate sets of genes in numerous bacteria. Phosphorylation of the regulator at an unprecedented position abolished binding in vitro to a putative partner. Remarkably, increasing PknD activity in Mtb not only strongly activated the gene encoding the specific regulatory protein phosphorylated by PknD, but also altered the expression of genes controlled by an alternative sigma factor. By providing evidence for a mechanistic link between PknD and gene regulation, this work supports a new model in which STPKs in numerous microorganisms transduce environmental signals by controlling expression of specific groups of genes. Thus, certain bacterial STPKs may orchestrate aspects of the coordinate control of gene expression essential for adaptation in the environment and in host infections.
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Affiliation(s)
- Andrew E Greenstein
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
| | - Jason A MacGurn
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Christina E Baer
- Biophysics Graduate Group, University of California, Berkeley, California, United States of America
| | - Arnold M Falick
- Howard Hughes Medical Institute Mass Spectrometry Laboratory, University of California, Berkeley, California, United States of America
| | - Jeffery S Cox
- Department of Microbiology and Immunology, University of California San Francisco, San Francisco, California, United States of America
| | - Tom Alber
- Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America
- * To whom correspondence should be addressed. E-mail:
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70
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Igoshin OA, Brody MS, Price CW, Savageau MA. Distinctive topologies of partner-switching signaling networks correlate with their physiological roles. J Mol Biol 2007; 369:1333-52. [PMID: 17498739 PMCID: PMC2727513 DOI: 10.1016/j.jmb.2007.04.021] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2006] [Revised: 04/09/2007] [Accepted: 04/09/2007] [Indexed: 10/23/2022]
Abstract
Regulatory networks controlling bacterial gene expression often evolve from common origins and share homologous proteins and similar network motifs. However, when functioning in different physiological contexts, these motifs may be re-arranged with different topologies that significantly affect network performance. Here we analyze two related signaling networks in the bacterium Bacillus subtilis in order to assess the consequences of their different topologies, with the aim of formulating design principles applicable to other systems. These two networks control the activities of the general stress response factor sigma(B) and the first sporulation-specific factor sigma(F). Both networks have at their core a "partner-switching" mechanism, in which an anti-sigma factor forms alternate complexes either with the sigma factor, holding it inactive, or with an anti-anti-sigma factor, thereby freeing sigma. However, clear differences in network structure are apparent: the anti-sigma factor for sigma(F) forms a long-lived, "dead-end" complex with its anti-anti-sigma factor and ADP, whereas the genes encoding sigma(B) and its network partners lie in a sigma(B)-controlled operon, resulting in positive and negative feedback loops. We constructed mathematical models of both networks and examined which features were critical for the performance of each design. The sigma(F) model predicts that the self-enhancing formation of the dead-end complex transforms the network into a largely irreversible hysteretic switch; the simulations reported here also demonstrate that hysteresis and slow turn off kinetics are the only two system properties associated with this complex formation. By contrast, the sigma(B) model predicts that the positive and negative feedback loops produce graded, reversible behavior with high regulatory capacity and fast response time. Our models demonstrate how alterations in network design result in different system properties that correlate with regulatory demands. These design principles agree with the known or suspected roles of similar networks in diverse bacteria.
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Affiliation(s)
- Oleg A. Igoshin
- Department of Biomedical Engineering, University of California, Davis, CA, 95616
| | - Margaret S. Brody
- Department of Food Science, University of California, Davis, CA, 95616
| | - Chester W. Price
- Department of Food Science, University of California, Davis, CA, 95616
| | - Michael A. Savageau
- Department of Biomedical Engineering, University of California, Davis, CA, 95616
- Corresponding author: e-mail: ; phone 1(530) 754-8375; fax: 1(530) 7545739
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71
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Hardwick SW, Pané-Farré J, Delumeau O, Marles-Wright J, Murray JW, Hecker M, Lewis RJ. Structural and functional characterization of partner switching regulating the environmental stress response in Bacillus subtilis. J Biol Chem 2007; 282:11562-72. [PMID: 17303566 DOI: 10.1074/jbc.m609733200] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The general stress response of Bacillus subtilis and close relatives provides the cell with protection from a variety of stresses. The upstream component of the environmental stress signal transduction cascade is activated by the RsbT kinase that switches binding partners from a 25 S macromolecular complex, the stressosome, to the RsbU phosphatase. Once the RsbU phosphatase is activated by interacting with RsbT, the alternative sigma factor, sigmaB, directs transcription of the general stress regulon. Previously, we demonstrated that the N-terminal domain of RsbU mediates the binding of RsbT. We now describe residues in N-RsbU that are crucial to this interaction by experimentation both in vitro and in vivo. Furthermore, crystal structures of the N-RsbU mutants provide a molecular explanation for the loss of interaction. Finally, we also characterize mutants in RsbT that affect binding to both RsbU and a simplified, binary model of the stressosome and thus identify overlapping binding surfaces on the RsbT "switch."
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Affiliation(s)
- Steven W Hardwick
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, United Kingdom
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72
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Reeves A, Haldenwang WG. Isolation and characterization of dominant mutations in the Bacillus subtilis stressosome components RsbR and RsbS. J Bacteriol 2006; 189:1531-41. [PMID: 17158665 PMCID: PMC1855730 DOI: 10.1128/jb.01649-06] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The general stress response of Bacillus subtilis is controlled by the activity state of the sigma(B) transcription factor. Physical stress is communicated to sigma(B) via a large-molecular-mass (>10(6)-Da) structure (the stressosome) formed by one or more members of a family of homologous proteins (RsbR, YkoB, YojH, YqhA). The positive regulator (RsbT) of the sigma(B) stress induction pathway is incorporated into the complex bound to an inhibitor protein (RsbS). Exposure to stress empowers an RsbT-dependent phosphorylation of RsbR and RsbS, with the subsequent release of RsbT to activate downstream processes. The mechanism by which stress initiates these reactions is unknown. In an attempt to identify changes in stressosome components that could lead to sigma(B) activation, a DNA segment encoding these proteins was mutagenized and placed into B. subtilis to create a merodiploid strain for these genes. Eight mutations that allowed heightened sigma(B) activity in the presence of their wild-type counterparts were isolated. Two of the mutations are missense changes in rsbR, and six are amino acid changes in rsbS. Additional experiments suggested that both of the rsbR mutations and three of the rsbS mutations likely enhance sigma(B) activity by elevating the level of RsbS phosphorylation. All of the mutations were found to be dominant over wild-type alleles only when they are cotranscribed within an rsbR rsbS rsbT operon. The data suggest that changes in RsbR can initiate the downstream events that lead to sigma(B) activation and that RsbR, RsbS, and RsbT likely interact with each other concomitantly with their synthesis.
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Affiliation(s)
- Adam Reeves
- Department of Microbiology and Immunology-MC7758, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
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73
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Gaidenko TA, Kim TJ, Weigel AL, Brody MS, Price CW. The blue-light receptor YtvA acts in the environmental stress signaling pathway of Bacillus subtilis. J Bacteriol 2006; 188:6387-95. [PMID: 16923906 PMCID: PMC1595380 DOI: 10.1128/jb.00691-06] [Citation(s) in RCA: 117] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
The general stress response of the bacterium Bacillus subtilis is regulated by a partner-switching mechanism in which serine and threonine phosphorylation controls protein interactions in the stress-signaling pathway. The environmental branch of this pathway contains a family of five paralogous proteins that function as negative regulators. Here we present genetic evidence that a sixth paralog, YtvA, acts as a positive regulator in the same environmental signaling branch. We also present biochemical evidence that YtvA and at least three of the negative regulators can be isolated from cell extracts in a large environmental signaling complex. YtvA differs from these associated negative regulators by its flavin mononucleotide (FMN)-containing light-oxygen-voltage domain. Others have shown that this domain has the photochemistry expected for a blue-light sensor, with the covalent linkage of the FMN chromophore to cysteine 62 composing a critical part of the photocycle. Consistent with the view that light intensity modifies the output of the environmental signaling pathway, we found that cysteine 62 is required for YtvA to exert its positive regulatory role in the absence of other stress. Transcriptional analysis of the ytvA structural gene indicated that it provides the entry point for at least one additional environmental input, mediated by the Spx global regulator of disulfide stress. These results support a model in which the large signaling complex serves to integrate multiple environmental signals in order to modulate the general stress response.
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Affiliation(s)
- Tatiana A Gaidenko
- Department of Food Science and Technology University of California, Davis, CA 95616, USA
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74
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Delumeau O, Chen CC, Murray JW, Yudkin MD, Lewis RJ. High-molecular-weight complexes of RsbR and paralogues in the environmental signaling pathway of Bacillus subtilis. J Bacteriol 2006; 188:7885-92. [PMID: 16963570 PMCID: PMC1636303 DOI: 10.1128/jb.00892-06] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bacillus subtilis has developed an intricate signal transduction cascade to respond to the imposition of a variety of stresses on the cell. Reversible protein phosphorylation and the formation of alternative protein-protein complexes modulate the activity of sigma(B), the RNA polymerase sigma factor subunit responsible for the transcription of the general stress response genes. Some of the regulators of sigma(B), such as RsbR and RsbS, are known to associate in a 25S complex, called the stressosome, that can bind RsbT until RsbT phosphorylates target residues in RsbR and RsbS. To date, the RsbR-RsbS complex appears to be the most upstream component of the sigma(B) regulatory pathway. This large structure is thought to play an important role in sensing and/or integrating signals from different physical stresses. The roles of the paralogues of RsbR that are found in B. subtilis remain unclear. We describe here how the RsbR paralogues copurify with RsbR from B. subtilis cell lysates, and we demonstrate in vitro that the paralogues form large complexes either with RsbS or with a prepurified RsbR-RsbS binary complex. We conclude from these biochemical studies that stressosomes in B. subtilis cells contain minimally RsbS and all of the RsbT-phosphorylatable RsbR paralogues.
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Affiliation(s)
- Olivier Delumeau
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, United Kingdom
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75
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Chater KF, Chandra G. The evolution of development inStreptomycesanalysed by genome comparisons. FEMS Microbiol Rev 2006; 30:651-72. [PMID: 16911038 DOI: 10.1111/j.1574-6976.2006.00033.x] [Citation(s) in RCA: 102] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
There is considerable information about the genetic control of the processes by which mycelial Streptomyces bacteria form spore-bearing aerial hyphae. The recent acquisition of genome sequences for 16 species of actinobacteria, including two streptomycetes, makes it possible to try to reconstruct the evolution of Streptomyces differentiation by a comparative genomic approach, and to place the results in the context of current views on the evolution of bacteria. Most of the developmental genes evaluated are found only in actinobacteria that form sporulating aerial hyphae, with several being peculiar to streptomycetes. Only four (whiA, whiB, whiD, crgA) are generally present in nondifferentiating actinobacteria, and only two (whiA, whiG) are found in other bacteria, where they are widespread. Thus, the evolution of Streptomyces development has probably involved the stepwise acquisition of laterally transferred DNA, each successive acquisition giving rise either to regulatory changes that affect the conditions under which development is initiated, or to changes in cellular structure or morphology.
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Affiliation(s)
- Keith F Chater
- Department of Molecular Microbiology, John Innes Centre, Norwich Research Park, Colney, Norwich, UK.
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76
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Pané-Farré J, Jonas B, Förstner K, Engelmann S, Hecker M. The sigmaB regulon in Staphylococcus aureus and its regulation. Int J Med Microbiol 2006; 296:237-58. [PMID: 16644280 DOI: 10.1016/j.ijmm.2005.11.011] [Citation(s) in RCA: 136] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2005] [Revised: 10/05/2005] [Accepted: 11/01/2005] [Indexed: 11/30/2022] Open
Abstract
The Staphylococcus aureus genome codes for a sigma factor that shows close sequence similarity to the alternative sigma factor sigmaB of Bacillus subtilis. However, of the proteins controlling the activity of sigmaB in B. subtilis only RsbU, RsbV, and RsbW are encoded in the staphylococcal genome. Therefore, the regulation of the sigmaB activity must differ between these two bacterial species. The present study was designed (i) to describe the sigmaB regulon and (ii) to identify stimuli leading to an activation of sigmaB-dependent transcription. All conditions under which sigmaB was activated in S. aureus (heat shock, addition of MnCl2 or NaCl, alkaline shock) required the presence of RsbU, a positive regulator of sigmaB. In contrast to B. subtilis, a drop in the cellular ATP level caused by the addition of carbonyl cyanide m-chlorophenylhydrazone did not lead to an activation of sigmaB in S. aureus. Moreover, ethanol, a strong inductor of sigmaB activity in B. subtilis, also failed to induce sigmaB in S. aureus. Expression of sigB and sigmaB-dependent genes was enhanced following entry into stationary phase of cells grown in complex medium (LB medium). Our DNA microarray data indicated that 122 genes are positively regulated by sigmaB under alkaline stress conditions. Interestingly, only 12% of these genes have an orthologue in the B. subtilis sigmaB regulon, suggesting that the function of the sigmaB regulon in S. aureus is different from that in B. subtilis. We could show that sigmaB of S. aureus, in contrast to B. subtilis, may have a function in more basic cellular processes such as cell envelope composition, membrane transport processes and intermediary metabolism. sigmaB-dependent genes identified by the DNA microarray approach were subjected to detailed transcriptional analyses using primer extension and Northern blot techniques. These analyses confirmed our DNA microarray data and furthermore revealed different regulatory groups of sigmaB-dependent genes.
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Affiliation(s)
- Jan Pané-Farré
- Institut für Mikrobiologie, Ernst-Moritz-Arndt-Universität, F.-L.-Jahn-Str. 15, D-17487 Greifswald, Germany
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77
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Zhang S, Reeves A, Woodbury RL, Haldenwang WG. Coexpression patterns of sigma(B) regulators in Bacillus subtilis affect sigma(B) inducibility. J Bacteriol 2006; 187:8520-5. [PMID: 16321960 PMCID: PMC1317008 DOI: 10.1128/jb.187.24.8520-8525.2005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
RsbT is an essential component of the pathway that activates the Bacillus subtilis sigma(B) transcription factor in response to physical stress. rsbT is located within an operon that includes the genes for its principal negative regulator (RsbS) and the stress pathway component that it activates (RsbU), as immediate upstream and downstream neighbors. In the current work we demonstrate that RsbT's ability to function is strongly influenced by coexpression with these adjoining genes. When rsbT is expressed at a site displaced from rsbS and rsbU, RsbT accumulates but it is unable to activate sigma(B) following stress. RsbT activity is restored if rsbT is cotranscribed at the alternative site with the genes that normally abut it. Additionally, an rsbS allele whose product allows constitutively high RsbT-dependent sigma(B) activity displays this activity in rsbS merodiploid strains only when cotranscribed with rsbT and is recessive to a wild-type rsbS allele only if the wild-type rsbS gene is not cotranscribed with an rsbT gene of its own. The data suggest that RsbS and RsbT are synthesized in equivalent amounts and interact coincidently with their synthesis to form stable regulatory complexes that maintain RsbT in a state from which it can be stress activated.
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Affiliation(s)
- Shuyu Zhang
- Department of Microbiology and Immunology, MC7758, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA.
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78
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Zhang S, Haldenwang WG. Contributions of ATP, GTP, and redox state to nutritional stress activation of the Bacillus subtilis sigmaB transcription factor. J Bacteriol 2005; 187:7554-60. [PMID: 16267279 PMCID: PMC1280325 DOI: 10.1128/jb.187.22.7554-7560.2005] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The general stress regulon of Bacillus subtilis is induced by activation of the sigma(B) transcription factor. sigma(B) activation occurs when one of two phosphatases responds to physical or nutritional stress to activate a positive sigma(B) regulator by dephosphorylation. The signal that triggers the nutritional stress phosphatase (RsbP) is unknown; however, RsbP activation occurs under culture conditions (glucose/phosphate starvation, azide or decoyinine treatment) that reduce the cell's levels of ATP and/or GTP. Variances in nucleotide levels in these instances may be coincidental rather than causal. RsbP carries a domain (PAS) that in some regulatory systems can respond directly to changes in electron transport, proton motive force, or redox potential, changes that typically precede shifts in high-energy nucleotide levels. The current work uses Bacillus subtilis with mutations in the oxidative phosphorylation and purine nucleotide biosynthetic pathways in conjunction with metabolic inhibitors to better define the inducing signal for RsbP activation. The data argue that a drop in ATP, rather than changes in GTP, proton motive force, or redox state, is the key to triggering sigma(B) activation.
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Affiliation(s)
- Shuyu Zhang
- Department of Microbiology & Immunology, University of Texas Health Science Center, San Antonio, 78229-3900, USA
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79
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Murray JW, Delumeau O, Lewis RJ. Structure of a nonheme globin in environmental stress signaling. Proc Natl Acad Sci U S A 2005; 102:17320-5. [PMID: 16301540 PMCID: PMC1297668 DOI: 10.1073/pnas.0506599102] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2005] [Indexed: 11/18/2022] Open
Abstract
RsbR is a regulator of sigma(B), the RNA polymerase sigma factor subunit responsible for transcribing the general stress response genes when environmental stress is imposed on Bacillus subtilis. The C-terminal domain of RsbR and its paralogues is a substrate for the kinase function of another sigma(B) regulator, RsbT, but the amino acid sequence of the N-terminal domain of RsbR does not reveal any obvious biochemical function. RsbR, its paralogues, and other regulators of sigma(B), including RsbS and RsbT, form large signaling complexes, called stressosomes. We have determined and present here the crystal structure of the N-terminal domain of RsbR. Unexpectedly, this structure belongs to the globin fold superfamily, but there is no bound cofactor. The globin domain from globin-coupled sensory systems replaces the N-terminal domain of RsbR in some bacteria, indicating a common genetic ancestry for RsbR and the globin family. We suggest that the globin fold has been "recycled" in RsbR and that one more activity can be included in the repertoire of globin functions, namely the ability to bind signaling macromolecules such as RsbT.
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Affiliation(s)
- James W Murray
- Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle, Newcastle upon Tyne, UK
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80
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Pané-Farré J, Lewis RJ, Stülke J. The RsbRST Stress Module in Bacteria: A Signalling System That May Interact with Different Output Modules. J Mol Microbiol Biotechnol 2005; 9:65-76. [PMID: 16319496 DOI: 10.1159/000088837] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In the Gram-positive bacterium Bacillus subtilis, the activity of the alternative sigma factor sigma(B) is triggered upon exposure of the bacteria to environmental stress conditions or to nutrient limitation. sigma(B) activity is controlled by protein-phosphorylation-dependent interactions of anti-sigma with anti-anti-sigma factors. Under stress conditions, the phosphatase RsbU triggers release of sigma(B) and thus induces the expression of stress genes. RsbU activity is controlled by three proteins, RsbR, RsbS and RsbT which form a supramolecular complex called the stressosome. Here we review the occurrence of the genes encoding the stressosome proteins (called the RsbRST module) in a wide variety of bacteria. While this module is linked to the gene encoding sigma(B) and its direct regulators in B. subtilis and its close relatives, genes encoding two-component regulatory systems and more complex phosphorelays are clustered with the RsbRST module in bacteria as diverse as cyanobacteria, bacteroidetes, proteobacteria, and deinococci. The conservation of the RsbRST module and its clustering with different types of regulatory systems suggest that the stressosome proteins form a signal sensing and transduction unit that relays information to very different output modules.
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Affiliation(s)
- Jan Pané-Farré
- Institut für Mikrobiologie, Ernst-Moritz-Arndt-Universität Greifswald, Greifswald, Deutschland
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81
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van Schaik W, Abee T. The role of sigmaB in the stress response of Gram-positive bacteria -- targets for food preservation and safety. Curr Opin Biotechnol 2005; 16:218-24. [PMID: 15831390 DOI: 10.1016/j.copbio.2005.01.008] [Citation(s) in RCA: 104] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
The alternative sigma factor sigmaB modulates the stress response of several Gram-positive bacteria, including Bacillus subtilis and the food-borne human pathogens Bacillus cereus, Listeria monocytogenes and Staphylococcus aureus. In all these bacteria, sigmaB is responsible for the transcription of genes that can confer stress resistance to the vegetative cell. Recent findings indicate that sigmaB also plays an important role in antibiotic resistance, pathogenesis and cellular differentiation processes such as biofilm formation and sporulation. Although there are important differences in the regulation of sigmaB and in the set of genes regulated by sigmaB in B. subtilis, B. cereus, L. monocytogenes and S. aureus, there are also some conserved themes. A mechanistic understanding of the sigmaB activation processes and assessment of its regulon could provide tools for pathogen control and inactivation both in the food industry and clinical settings.
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Affiliation(s)
- Willem van Schaik
- Wageningen Centre for Food Sciences and Laboratory of Food Microbiology, Wageningen University, Bomenweg 2, 6703 HD, Wageningen, The Netherlands
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82
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van Schaik W, Tempelaars MH, Zwietering MH, de Vos WM, Abee T. Analysis of the role of RsbV, RsbW, and RsbY in regulating {sigma}B activity in Bacillus cereus. J Bacteriol 2005; 187:5846-51. [PMID: 16077134 PMCID: PMC1196065 DOI: 10.1128/jb.187.16.5846-5851.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Accepted: 05/24/2005] [Indexed: 12/23/2022] Open
Abstract
The alternative sigma factor sigma(B) is an important regulator of the stress response of Bacillus cereus. Here, the role of the regulatory proteins RsbV, RsbW, and RsbY in regulating sigma(B) activity in B. cereus is analyzed. Functional characterization of RsbV and RsbW showed that they act as an anti-sigma factor antagonist and an anti-sigma factor, respectively. RsbW can also act as a kinase on RsbV. These data are in line with earlier functional characterizations of RsbV and RsbW homologs in B. subtilis. The rsbY gene is unique to B. cereus and its closest relatives and is predicted to encode a protein with an N-terminal CheY domain and a C-terminal PP2C domain. In an rsbY deletion mutant, the sigma(B) response upon stress exposure was almost completely abolished, but the response could be restored by complementation with full-length rsbY. Expression analysis showed that rsbY is transcribed from both a sigma(A)-dependent promoter and a sigma(B)-dependent promoter. The central role of RsbY in regulating the activity of sigma(B) indicates that in B. cereus, the sigma(B) activation pathway is markedly different from that in other gram-positive bacteria.
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83
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Chen CC, Yudkin MD, Delumeau O. Phosphorylation and RsbX-dependent dephosphorylation of RsbR in the RsbR-RsbS complex of Bacillus subtilis. J Bacteriol 2004; 186:6830-6. [PMID: 15466036 PMCID: PMC522205 DOI: 10.1128/jb.186.20.6830-6836.2004] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the pathway that controls sigmaB activity, the RsbR-RsbS complex plays an important role by trapping RsbT, a positive regulator of sigmaB of Bacillus subtilis. We have proposed that at the onset of stress, RsbR becomes phosphorylated, resulting in an enhanced activity of RsbT towards RsbS. RsbT is then free to interact with and activate RsbU, which in turn ultimately activates sigmaB. In this study with purified proteins, we used mutant RsbR proteins to analyze the role of its phosphorylatable threonine residues. The results show that the phosphorylation of either of the two RsbT-phosphorylatable threonine residues (T171 and T205) in RsbR enhanced the kinase activity of RsbT towards RsbS. However, it appeared that RsbT preferentially phosphorylates T171. We also present in vitro evidence that identifies RsbX as a potential phosphatase for RsbR T205.
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Affiliation(s)
- Chien-Cheng Chen
- Microbiology Unit, Department of Biochemistry, University of Oxford, South Parks Rd., Oxford OX1 3QU, United Kingdom
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84
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Zhang S, Haldenwang WG. Guanine nucleotides stabilize the binding of Bacillus subtilis Obg to ribosomes. Biochem Biophys Res Commun 2004; 322:565-9. [PMID: 15325267 DOI: 10.1016/j.bbrc.2004.07.154] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Indexed: 11/30/2022]
Abstract
Obg is a GTP-binding protein of Bacillus subtilis with essential, but undefined roles in the bacterium's growth, sporulation, and stress responses. Obg orthologs are widely conserved among both bacteria and eukaryotes. Gel filtration and affinity blot assays have suggested that Obg may be ribosome-associated. In the current work, we continue an examination of the putative Obg:ribosome interaction. Velocity centrifugation analyses of crude B. subtilis extracts or purified Obg:ribosome mixtures suggest that Obg is initially ribosome-bound, but can separate from ribosomes during sedimentation in the absence of added nucleotides. Addition of either GTP, GDP or ATP to the gradient prolonged the Obg:ribosome association, while inclusion of a nonhydrolyzable GTP analog (5-guanylyl-imidodiphosphate) preserved it. The data strengthen the notion that Obg is a ribosome-associated protein, demonstrate that Obg's association with ribosomes is stabilized by GTP, and indicate that the ribosome-bound Obg can likely hydrolyze GTP and be released as a consequence.
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Affiliation(s)
- Shuyu Zhang
- Department of Microbiology and Immunology, University of Texas Health Science Center, San Antonio, TX 78229-3900, USA
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85
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Abstract
Traditional textbook representations of the prokaryotic cytoplasm show an amorphous, unstructured amalgamation of proteins and small molecules in which a randomly arranged chromosome resides. The development and application of a swathe of microscopic techniques over the last 10 years in particular, has shown this image of the microbial cell to be incorrect: the cytoplasm is highly structured with many proteins carrying out their assigned functions at specific subcellular locations; bacteria contain cytoskeletal elements including microtubule, actin and intermediate filament homologues; the chromosome is not randomly folded and is organized in such a way as to facilitate efficient segregation upon cell division. This review will concentrate on recent advances in our understanding of subcellular architecture and the techniques that have led to these discoveries.
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Affiliation(s)
- Peter J Lewis
- School of Environmental and Life Sciences, Biological Sciences, University of Newcastle, Callaghan, NSW 2308, Australia.
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86
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Kim TJ, Gaidenko TA, Price CW. In vivo phosphorylation of partner switching regulators correlates with stress transmission in the environmental signaling pathway of Bacillus subtilis. J Bacteriol 2004; 186:6124-32. [PMID: 15342582 PMCID: PMC515174 DOI: 10.1128/jb.186.18.6124-6132.2004] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Exposure of bacteria to diverse growth-limiting stresses induces the synthesis of a common set of proteins which provide broad protection against future, potentially lethal stresses. Among Bacillus subtilis and its relatives, this general stress response is controlled by the sigmaB transcription factor. Signals of environmental and energy stress activate sigmaB through a multicomponent network that functions via a partner switching mechanism, in which protein-protein interactions are governed by serine and threonine phosphorylation. Here, we tested a central prediction of the current model for the environmental signaling branch of this network. We used isoelectric focusing and immunoblotting experiments to determine the in vivo phosphorylation states of the RsbRA and RsbS regulators, which act in concert to negatively control the RsbU environmental signaling phosphatase. As predicted by the model, the ratio of the phosphorylated to unphosphorylated forms of both RsbRA and RsbS increased in response to salt or ethanol stress. However, these two regulators differed substantially with regard to the extent of their phosphorylation under both steady-state and stress conditions, with RsbRA always the more highly modified. Mutant analysis showed that the RsbT kinase, which is required for environmental signaling, was also required for the in vivo phosphorylation of RsbRA and RsbS. Moreover, the T171A alteration of RsbRA, which blocks environmental signaling, also blocked in vivo phosphorylation of RsbRA and impeded phosphorylation of RsbS. These in vivo results corroborate previous genetic analyses and link the phosphorylated forms of RsbRA and RsbS to the active transmission of environmental stress signals.
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Affiliation(s)
- Tae-Jong Kim
- Department of Food Science and Technology, University of California, Davis, CA 95616, USA
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87
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Moore CM, Nakano MM, Wang T, Ye RW, Helmann JD. Response of Bacillus subtilis to nitric oxide and the nitrosating agent sodium nitroprusside. J Bacteriol 2004; 186:4655-64. [PMID: 15231799 PMCID: PMC438601 DOI: 10.1128/jb.186.14.4655-4664.2004] [Citation(s) in RCA: 115] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We examined the effects of nitric oxide (NO) and sodium nitroprusside (SNP) on Bacillus subtilis physiology and gene expression. In aerobically growing cultures, cell death was most pronounced when NO gas was added incrementally rather than as a single bolus, suggesting that the length of exposure was important in determining cell survival. DNA microarrays, Northern hybridizations, and RNA slot blot analyses were employed to characterize the global transcriptional response of B. subtilis to NO and SNP. Under both aerobic and anaerobic conditions the gene most highly induced by NO was hmp, a flavohemoglobin known to protect bacteria from NO stress. Anaerobically, NO also induced genes repressed by the Fe(II)-containing metalloregulators, Fur and PerR, consistent with the known ability of NO to nitrosylate the Fe(II) center in Fur. In support of this model, we demonstrate that NO fails to induce PerR-regulated genes under growth conditions that favor the formation of PerR:Mn(II) rather than PerR:Fe(II). Aerobically, NO gas induced hmp, the sigmaB general stress regulon, and, to a lesser extent, the Fur and PerR regulons. Surprisingly, NO gas induced the sigmaB regulon via the energy branch of the sigmaB regulatory cascade while induction by SNP was mediated by the environmental stress branch. This emphasizes that NO and SNP elicit genetically distinct stress responses.
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Affiliation(s)
- Charles M Moore
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
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88
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Delumeau O, Dutta S, Brigulla M, Kuhnke G, Hardwick SW, Völker U, Yudkin MD, Lewis RJ. Functional and structural characterization of RsbU, a stress signaling protein phosphatase 2C. J Biol Chem 2004; 279:40927-37. [PMID: 15263010 DOI: 10.1074/jbc.m405464200] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
RsbU is a positive regulator of the activity of sigmaB, the general stress-response sigma factor of Gram+ microorganisms. The N-terminal domain of this protein has no significant sequence homology with proteins of known function, whereas the C-terminal domain is similar to the catalytic domains of PP2C-type phosphatases. The phosphatase activity of RsbU is stimulated greatly during the response to stress by associating with a kinase, RsbT. This association leads to the induction of sigmaB activity. Here we present data on the activation process and demonstrate in vivo that truncations in the N-terminal region of RsbU are deleterious for the activation of RsbU. This conclusion is supported by comparisons of the phosphatase activities of full-length and a truncated form of RsbU in vitro. Our determination of the crystal structure of the N-terminal domain of RsbU from Bacillus subtilis reveals structural similarities to the regulatory domains from ubiquitous protein phosphatases and a conserved domain of sigma-factors, illuminating the activation processes of phosphatases and the evolution of "partner switching." Finally, the molecular basis of kinase recruitment by the RsbU phosphatase is discussed by comparing RsbU sequences from bacteria that either possess or lack RsbT.
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Affiliation(s)
- Olivier Delumeau
- Microbiology Unit and Laboratory of Molecular Biophysics, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
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89
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Kim TJ, Gaidenko TA, Price CW. A Multicomponent Protein Complex Mediates Environmental Stress Signaling in Bacillus subtilis. J Mol Biol 2004; 341:135-50. [PMID: 15312768 DOI: 10.1016/j.jmb.2004.05.043] [Citation(s) in RCA: 75] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2003] [Revised: 05/10/2004] [Accepted: 05/19/2004] [Indexed: 11/26/2022]
Abstract
Activity of the general stress transcription factor sigma(B) of Bacillus subtilis is regulated directly by a partner-switching mechanism in which key protein interactions are governed by serine phosphorylation. Signals of energy or environmental stress are conveyed to sigma(B) by independent pathways, each terminating with a differentially regulated serine phosphatase, whose activity is required to control the partner-switching regulators. We present genetic and biochemical evidence that activation of the RsbU environmental signaling phosphatase is modulated by a second, atypical partner switch that comprises redundant negative regulatory proteins in a large, multicomponent signaling complex. In the current model, negative regulation of the RsbU phosphatase depends solely on the RsbS antagonist protein. Here, we perform a critical genetic test that invalidates this model and demonstrates that the RsbS antagonist alone is insufficient to prevent environmental signaling. Also required is one of a family of four co-antagonist proteins, here renamed RsbRA, RsbRB, RsbRC, and RsbRD, each with a carboxyl-terminal domain closely resembling the entire RsbS protein. Because any single member of the RsbR family, together with RsbS, was sufficient for environmental signaling, we conclude that the RsbR proteins serve as redundant co-antagonists necessary for RsbS antagonist function. Moreover, purification of RsbRA from cell extracts by nickel affinity and gel-filtration chromatography found a multicomponent complex containing the RsbRA and RsbRB co-antagonists together with the RsbS antagonist. We propose that this complex serves as a machine to transmit stress signals to sigma(B), and that the properties of the complex may contribute to environmental stress sensing.
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Affiliation(s)
- Tae-Jong Kim
- Department of Food Science and Technology, University of California, Davis, CA 95616, USA
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90
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Woodbury RL, Luo T, Grant L, Haldenwang WG. Mutational analysis of RsbT, an activator of the Bacillus subtilis stress response transcription factor, sigmaB. J Bacteriol 2004; 186:2789-97. [PMID: 15090521 PMCID: PMC387813 DOI: 10.1128/jb.186.9.2789-2797.2004] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
SigmaB, the stress-activated sigma factor of Bacillus subtilis, requires the RsbT protein as an essential positive regulator of its physical stress pathway. Stress triggers RsbT to both inactivate the principal negative regulator of the physical stress pathway (RsbS) by phosphorylation and activate a phosphatase (RsbU) required for sigmaB induction. Neither the regions of RsbT that are involved in responding to stress signaling nor those required for downstream events have been established. We used alanine scanning mutagenesis to examine the contributions of RsbT's charged amino acids to the protein's stability and activities. Eleven of eighteen rsbT mutations blocked sigmaB induction by stress. The carboxy terminus of RsbT proved to be particularly important for accumulation in Bacillus subtilis. Four of the five most carboxy-terminal mutations yielded rsbT alleles whose products were undetectable in B. subtilis extracts. Charged amino acids in the central region of RsbT were less critical, with four of the five substitutions in this region having no measurable effect on RsbT accumulation or activity. Only when the substitutions extended into a region of kinase homology was sigmaB induction affected. Six other RsbT variants, although present at levels adequate for activity, failed to activate sigmaB and displayed significant changes in their ability to interact with RsbT's normal binding partners in a yeast dihybrid assay. These changes either dramatically altered the proteins' tertiary structure without affecting their stability or defined regions of RsbT that are involved in multiple interactions.
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Affiliation(s)
- Robyn L Woodbury
- Department of Microbiology and Immunology, University of Texas Health Science Center, 7703 Floyd Curl Drive, San Antonio, TX 78229-3900, USA
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91
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Perego M, Hoch JA, Barrett JF. Functional genomics of gram-positive microorganisms. J Bacteriol 2004; 186:903-9. [PMID: 14761984 PMCID: PMC344236 DOI: 10.1128/jb.186.4.903-909.2004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Affiliation(s)
- Marta Perego
- Division of Cellular Biology, Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
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