期刊
MOLECULAR MICROBIOLOGY
卷 39, 期 4, 页码 1036-1047出版社
BLACKWELL SCIENCE LTD
DOI: 10.1046/j.1365-2958.2001.02298.x
关键词
-
In the Gram-positive bacterium, Streptomyces coelicolor A3(2), expression of the thioredoxin system is modulated by a sigma factor called sigma (R) in response to changes in the cytoplasmic thiol-disulphide status, and the activity of sigma (R) is controlled post-translationally by an anti-sigma factor, RsrA. In vitro, the anti-sigma factor activity of RsrA, which contains seven cysteines, correlates with its thiol-disulphide redox status. Here, we investigate the function of RsrA in vivo. A constructed rsrA null mutant had very high constitutive levels of disulphide reductase activity and sigma (R)-dependent transcription, confirming that RsrA is a negative regulator of sigma (R) and a key sensor of thiol-disulphide status. Targeted mutagenesis revealed that three of the seven cysteines in RsrA (C11, C41 and C44) were essential for anti-sigma factor activity and that a mutant RsrA protein containing only these three cysteines was active and still redox sensitive in vivo. We also show that RsrA is a metalloprotein, containing near-stoichiometric amounts of zinc. On the basis of these data, we propose that a thiol-disulphide redox switch is formed between two of C11, C41 and C44, and that all three residues play an essential role in anti-sigma factor activity in their reduced state, perhaps by acting as ligands for zinc. Unexpectedly, rsrA null mutants were blocked in sporulation, probably as a consequence of an increase in the level of free sigma (R).
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据