A conserved structural module regulates transcriptional responses to diverse stress signals in bacteria.
A transcriptional response to singlet oxygen in Rhodobacter sphaeroides is controlled by the group IV sigma factor sigma(E) and its cognate anti-sigma ChrR. Crystal structures of the sigma(E)/ChrR complex reveal a modular, two-domain architecture for ChrR. The ChrR N-terminal anti-sigma domain (ASD) binds a Zn(2+) ion, contacts sigma(E), and is sufficient to inhibit sigma(E)-dependent transcription. The ChrR C-terminal domain adopts a cupin fold, can coordinate an additional Zn(2+), and is required for the transcriptional response to singlet oxygen. Structure-based sequence analyses predict that the ASD defines a common structural fold among predicted group IV anti-sigmas. These ASDs are fused to diverse C-terminal domains that are likely involved in responding to specific environmental signals that control the activity of their cognate sigma factor.
Campbell
Elizabeth A
EA
The Rockefeller University, 1230 York Avenue, New York, NY 10021, USA.
Greenwell
Roger
R
Anthony
Jennifer R
JR
Wang
Sheng
S
Lim
Lionel
L
Das
Kalyan
K
Sofia
Heidi J
HJ
Donohue
Timothy J
TJ
Darst
Seth A
SA
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D001665:Binding Sites; D018360:Crystallography, X-Ray; D015964:Gene Expression Regulation, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D012242:Rhodobacter sphaeroides / Q000235:genetics* / Q000378:metabolism; D016415:Sequence Alignment; D012808:Sigma Factor / Q000737:chemistry* / Q000502:physiology; D014157:Transcription Factors / Q000737:chemistry* / Q000502:physiology; D014158:Transcription, Genetic / Q000502:physiology*; D015032:Zinc / Q000378:metabolism