Title of article :
Identification and Structure of the Anti-sigma Factor-binding Domain of the Disulphide-stress Regulated Sigma Factor σR from Streptomyces coelicolor
Author/Authors :
Wei Li، نويسنده , , Clare E.M Stevenson، نويسنده , , Nicolas Burton، نويسنده , , Piotr Jakimowicz، نويسنده , , Mark S.B. Paget، نويسنده , , Mark J. Buttner، نويسنده , , David M. Lawson، نويسنده , , Colin Kleanthous and Andrew M Hemmings، نويسنده ,
Issue Information :
روزنامه با شماره پیاپی سال 2002
Pages :
12
From page :
225
To page :
236
Abstract :
The extracytoplasmic function (ECF) sigma factor σR is a global regulator of redox homeostasis in the antibiotic-producing bacterium Streptomyces coelicolor, with a similar role in other actinomycetes such as Mycobacterium tuberculosis. Normally maintained in an inactive state by its bound anti-sigma factor RsrA, σR dissociates in response to intracellular disulphide-stress to direct core RNA polymerase to transcribe genes, such as trxBA and trxC that encode the enzymes of the thioredoxin disulphide reductase pathway, that re-establish redox homeostasis. Little is known about where RsrA binds on σR or how it suppresses σR-dependent transcriptional activity. Using a combination of proteolysis, surface-enhanced laser desorption ionisation mass spectrometry and pull-down assays we identify an N-terminal, ∼10 kDa domain (σRN) that encompasses region 2 of σR that represents the major RsrA binding site. We show that σRN inhibits transcription by an unrelated sigma factor and that this inhibition is relieved by RsrA binding, reaffirming that region 2 is involved in binding to core RNA polymerase but also demonstrating that the likely mechanism by which RsrA inhibits σR activity is by blocking this association. We also report the 2.4 Å resolution crystal structure of σRN that reveals extensive structural conservation with the equivalent region of σ70 from Escherichia coli as well as with the cyclin-box, a domain-fold found in the eukaryotic proteins TFIIB and cyclin A. σRN has a propensity to aggregate, due to steric complementarity of oppositely charged surfaces on the domain, but this is inhibited by RsrA, an observation that suggests a possible mode of action for RsrA which we compare to other well-studied sigma factor-anti-sigma factor systems.
Keywords :
sigma factor , X-ray crystallography , structure , S. coelicolor , RsrA
Journal title :
Journal of Molecular Biology
Serial Year :
2002
Journal title :
Journal of Molecular Biology
Record number :
1242091
Link To Document :
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