TY - JOUR
T1 - Structural and functional analysis of RopB
T2 - A major virulence regulator in Streptococcus pyogenes
AU - Makthal, Nishanth
AU - Gavagan, Maire
AU - Do, Hackwon
AU - Olsen, Randall J.
AU - Musser, James M.
AU - Kumaraswami, Muthiah
N1 - Funding Information:
This work was supported by the National Institute of Health grants (1R21AI103708-01 and 1R01AI109096-01A1 to M.K). Advanced Light Source was supported by Department of Energy contract DE-AC03-76SF00098. The authors declare no conflicts of interest. The coordinates and structure factors for the RopB-CTD structure have been deposited to the protein data bank (PDB) with the accession code of 5DL2.
Publisher Copyright:
© 2016 John Wiley & Sons Ltd.
PY - 2016/3/1
Y1 - 2016/3/1
N2 - Group A Streptococcus (GAS) is an exclusive human pathogen that causes significant disease burden. Global regulator RopB of GAS controls the expression of several major virulence factors including secreted protease SpeB during high cell density. However, the molecular mechanism for RopB-dependent speB expression remains unclear. To understand the mechanism of transcription activation by RopB, we determined the crystal structure of the C-terminal domain of RopB. RopB-CTD has the TPR motif, a signature motif involved in protein-peptide interactions and shares significant structural homology with the quorum sensing RRNPP family regulators. Characterization of the high cell density-specific cell-free growth medium demonstrated the presence of a low molecular weight proteinaceous secreted factor that upregulates RopB-dependent speB expression. Together, these results suggest that RopB and its cognate peptide signals constitute an intercellular signalling machinery that controls the virulence gene expression in concert with population density. Structure-guided mutational analyses of RopB dimer interface demonstrated that single alanine substitutions at this critical interface significantly altered RopB-dependent speB expression and attenuated GAS virulence. Results presented here suggested that a properly aligned RopB dimer interface is important for GAS pathogenesis and highlighted the dimerization interactions as a plausible therapeutic target for the development of novel antimicrobials.
AB - Group A Streptococcus (GAS) is an exclusive human pathogen that causes significant disease burden. Global regulator RopB of GAS controls the expression of several major virulence factors including secreted protease SpeB during high cell density. However, the molecular mechanism for RopB-dependent speB expression remains unclear. To understand the mechanism of transcription activation by RopB, we determined the crystal structure of the C-terminal domain of RopB. RopB-CTD has the TPR motif, a signature motif involved in protein-peptide interactions and shares significant structural homology with the quorum sensing RRNPP family regulators. Characterization of the high cell density-specific cell-free growth medium demonstrated the presence of a low molecular weight proteinaceous secreted factor that upregulates RopB-dependent speB expression. Together, these results suggest that RopB and its cognate peptide signals constitute an intercellular signalling machinery that controls the virulence gene expression in concert with population density. Structure-guided mutational analyses of RopB dimer interface demonstrated that single alanine substitutions at this critical interface significantly altered RopB-dependent speB expression and attenuated GAS virulence. Results presented here suggested that a properly aligned RopB dimer interface is important for GAS pathogenesis and highlighted the dimerization interactions as a plausible therapeutic target for the development of novel antimicrobials.
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U2 - 10.1111/mmi.13294
DO - 10.1111/mmi.13294
M3 - Article
C2 - 26714274
AN - SCOPUS:84975705639
SN - 0950-382X
VL - 99
SP - 1119
EP - 1133
JO - Molecular Microbiology
JF - Molecular Microbiology
IS - 6
ER -