The bacterial stressosome: a modular system that has been adapted to control secondary messenger signaling.
The stressosome complex regulates downstream effectors in response to environmental signals. In Bacillus subtilis, it activates the alternative sigma factor σ(B), leading to the upregulation of the general stress regulon. Herein, we characterize a stressosome-regulated biochemical pathway in Moorella thermoacetica. We show that the presumed sensor, MtR, and the scaffold, MtS, form a pseudo-icosahedral structure like that observed in B. subtilis. The N-terminal domain of MtR is structurally homologous to B. subtilis RsbR, despite low sequence identity. The affinity of the switch kinase, MtT, for MtS decreases following MtS phosphorylation and not because of structural reorganization. Dephosphorylation of MtS by the PP2C type phosphatase MtX permits the switch kinase to rebind the stressosome to reset the response. We also show that MtT regulates cyclic di-GMP biosynthesis through inhibition of a GG(D/E)EF-type diguanylate cyclase, demonstrating that secondary messenger levels are regulated by the stressosome.
Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK.
Maureen B
MB
Quin
John M
JM
Berrisford
Joseph A
JA
Newman
Arnaud
A
Baslé
Richard J
RJ
Lewis
Jon
J
Marles-Wright
D020816:Amino Acid Motifs; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D020134:Catalytic Domain; D017124:Conserved Sequence; D018360:Crystallography, X-Ray; D006152:Cyclic GMP / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D058845:Moorella; D046912:Multiprotein Complexes / Q000737:chemistry / Q000235:genetics; D009876:Operon; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics; D010744:Phosphoric Monoester Hydrolases / Q000737:chemistry / Q000235:genetics; D019761:Phosphorus-Oxygen Lyases / Q000737:chemistry / Q000235:genetics; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics; D020836:Protein Structure, Quaternary; D015290:Second Messenger Systems
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D046912:Multiprotein Complexes; D010750:Phosphoproteins; D011494:Protein Kinases; D010744:Phosphoric Monoester Hydrolases; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase; D006152:Cyclic GMP