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Category: Bacterial Pathogenesis; Microbial Genetics and Molecular Biology
Two-Component Regulatory Systems, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555818388/9781555810535_Chap50-1.gif /docserver/preview/fulltext/10.1128/9781555818388/9781555810535_Chap50-2.gifAbstract:
Originally characterized for nitrogen regulation (NtrB-NtrC), chemotaxis (CheA-CheY-CheB), osmoregulation (EnvZ-OmpR), and regulation of phosphate uptake (PhoR-PhoB) in Escherichia coli and Salmonella typhimurium, the family of two-component systems has rapidly expanded, and new examples continue to emerge. More than 30 of these regulatory pairs have been identified in both gram-negative and gram-positive bacteria; they control functions ranging from virulence gene expression in Agrobacterium tumefaciens (VirA-VirG), S. typhimurium (PhoQ-PhoP), and Bordetella pertussis (BvgSBvgA) to complex developmental pathways such as sporulation (SpoIIJ-SpoOF-SpoOA) and competence for transformation by exogenous DNA (ComP-ComA and DegS-DegU) in Bacillus subtilis. These pairs are the focus of this chapter. Sequence similarities to other two-component systems suggest the conserved His-189 residue of the DegS protein kinase and Asp-56 residue of the DegU response regulator as likely candidates for the respective phosphorylation sites of the two proteins. A large number of proteins belonging to the histidine protein kinase-response regulator family have been characterized in gram-positive bacteria. It appears that a considerable amount of overlap exists between the different systems controlling postexponential-phase responses in B. subtilis. Thus, DegS-DegU, ComP-ComA, and SpoOA are all involved in controlling competence gene expression, and the SpoOA phosphorelay and DegS-DegU both control protease gene expression.
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Alignment of conserved regions within the carboxy-terminal domains of histidine protein kinases from gram-positive bacteria. Multiple protein sequence alignments were carried out by using the CLUSTAL V program ( 59 , 60 ). Protein sequences are from the references in Table 1 . Homologous residues are indicated by black boxes, stars indicate invariant residues, and numbers indicate positions in the amino acid sequences of the respective proteins. Accepted conservative substitutions are as follows: I, L, V, and M; K and R; S and T; D and E; F and Y; N and Q; G and A. Bs, B. subtilis; Sa, S. aureus; Ef, E. faecium.
Alignment of conserved regions within the carboxy-terminal domains of histidine protein kinases from gram-positive bacteria. Multiple protein sequence alignments were carried out by using the CLUSTAL V program ( 59 , 60 ). Protein sequences are from the references in Table 1 . Homologous residues are indicated by black boxes, stars indicate invariant residues, and numbers indicate positions in the amino acid sequences of the respective proteins. Accepted conservative substitutions are as follows: I, L, V, and M; K and R; S and T; D and E; F and Y; N and Q; G and A. Bs, B. subtilis; Sa, S. aureus; Ef, E. faecium.
Conserved carboxy-terminal domains of response regulators from gram-positive bacteria. Numbers correspond to positions in the respective amino acid sequences. References for the response regulators from gram-positive bacteria are listed in Table 1 . Comparisons were carried out as indicated in the legend to Fig. 1 . (A) Alignment of the OmpR-PhoP subfamily with OmpR of E. coli ( 27 , 167 ) and ToxR of V. cholerae ( 97 ). Ec, E. coli; Bs, B. subtilis; Ef, E. faecium; Sl, S. lividans; Vc, V. cholerae. (B) Alignment of the UhpA-DegU subfamily with the regulatory proteins RcsA and MalT of E. coli ( 25 , 43 , 148 ); RmpA of K. pneumoniae (Kp) ( 113 , 160 ); LasR and AgmR of P. aeruginosa (Pa) ( 45 , 132 ); LuxR of V. fischeri (Vf) ( 35 , 39 ); BrpA of S. hygroscopicus (Sh) ( 123 ); and GerE ( 28 ) and sigma factors σA(46), σB ( 15 ), and σE ( 149 ) of B. subtilis. A potential DNA-binding helix-turn-helix motif within this region is underlined.
Conserved carboxy-terminal domains of response regulators from gram-positive bacteria. Numbers correspond to positions in the respective amino acid sequences. References for the response regulators from gram-positive bacteria are listed in Table 1 . Comparisons were carried out as indicated in the legend to Fig. 1 . (A) Alignment of the OmpR-PhoP subfamily with OmpR of E. coli ( 27 , 167 ) and ToxR of V. cholerae ( 97 ). Ec, E. coli; Bs, B. subtilis; Ef, E. faecium; Sl, S. lividans; Vc, V. cholerae. (B) Alignment of the UhpA-DegU subfamily with the regulatory proteins RcsA and MalT of E. coli ( 25 , 43 , 148 ); RmpA of K. pneumoniae (Kp) ( 113 , 160 ); LasR and AgmR of P. aeruginosa (Pa) ( 45 , 132 ); LuxR of V. fischeri (Vf) ( 35 , 39 ); BrpA of S. hygroscopicus (Sh) ( 123 ); and GerE ( 28 ) and sigma factors σA(46), σB ( 15 ), and σE ( 149 ) of B. subtilis. A potential DNA-binding helix-turn-helix motif within this region is underlined.
Regulation of competence gene expression in B. subtilis. Arrows indicate positive regulation, and perpendicular bars indicate negative regulation. The ComP-ComA and DegS-DegU two-component systems form two parallel pathways controlling competence gene expression ( 37 ).
Regulation of competence gene expression in B. subtilis. Arrows indicate positive regulation, and perpendicular bars indicate negative regulation. The ComP-ComA and DegS-DegU two-component systems form two parallel pathways controlling competence gene expression ( 37 ).
Pleiotropic regulation by the DegS-DegU signal transduction pathway controlling degradative enzyme synthesis and competence gene expression in B. subtilis. Arrows indicate positive regulation, and perpendicular bars indicate negative regulation. Regulation by DegS-DegU, DegQ, and DegR may be indirect.
Pleiotropic regulation by the DegS-DegU signal transduction pathway controlling degradative enzyme synthesis and competence gene expression in B. subtilis. Arrows indicate positive regulation, and perpendicular bars indicate negative regulation. Regulation by DegS-DegU, DegQ, and DegR may be indirect.
Alignment of the conserved amino-terminal domains of response regulators from gram-positive bacteria. References for protein sequences are listed in Table 1 . Numbers correspond to positions in the respective amino acid sequences. Comparisons were carried out as indicated in the legend to Fig. 1 . Bs, B. subtilis; Bm, B. megaterium; Sa, S. aureus; Ef, E. faecium; Sl, S. lividans.
Alignment of the conserved amino-terminal domains of response regulators from gram-positive bacteria. References for protein sequences are listed in Table 1 . Numbers correspond to positions in the respective amino acid sequences. Comparisons were carried out as indicated in the legend to Fig. 1 . Bs, B. subtilis; Bm, B. megaterium; Sa, S. aureus; Ef, E. faecium; Sl, S. lividans.
Two-component regulatory pairs of gram-positive bacteria
Two-component regulatory pairs of gram-positive bacteria
Mutations in degS and degU genes and associated phenotypes
Mutations in degS and degU genes and associated phenotypes