High-molecular-weight complexes of RsbR and paralogues in the environmental signaling pathway of Bacillus subtilis.
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.
Delumeau
Olivier
O
Institute for Cell and Molecular Biosciences, Faculty of Medical Sciences, University of Newcastle, Newcastle upon Tyne NE2 4HH, United Kingdom.
Chen
Chien-Cheng
CC
Murray
James W
JW
Yudkin
Michael D
MD
Lewis
Richard J
RJ
D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D008970:Molecular Weight; D046912:Multiprotein Complexes / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction; D016622:Silver Staining
D001426:Bacterial Proteins; D046912:Multiprotein Complexes; D010750:Phosphoproteins; C119218:RsbR protein, Bacillus subtilis; C119219:RsbT protein, Bacillus subtilis; D017346:Protein Serine-Threonine Kinases