BACILLUS-SUBTILIS SIGMA-B IS REGULATED BY A BINDING-PROTEIN (RSBW) THAT BLOCKS ITS ASSOCIATION WITH CORE RNA-POLYMERASE
BACILLUS-SUBTILIS SIGMA-B IS REGULATED BY A BINDING-PROTEIN (RSBW) THAT BLOCKS ITS ASSOCIATION WITH CORE RNA-POLYMERASE
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DOI：
10.1073/pnas.90.6.2330
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发表时间：
1993-03-15
影响因子：
11.1
通讯作者：
HALDENWANG, WG
中科院分区：
文献类型：
--
作者：
BENSON, AK;HALDENWANG, WG
Sigma（B）是枯草芽孢杆菌的次级或因子。含有sigma（B）的RNA聚合酶转录在热休克或生长稳定期开始后表达的基因的子集。与sigma（B）结构基因（sigB）共转录的三个基因（rsbV、rsbW和rsbX）调节sigma（B）依赖性基因表达。RsbW是该系统的主要抑制剂，其他基因产物在sigma（B）调节途径中作用于RsbW的上游。现在有证据表明，RsbW通过与sigma（B）结合并阻断含有sigma（B）的RNA聚合酶全酶的形成来抑制sigma（B）依赖性转录。对RsbW或sigma（B）具有特异性的抗体将从粗细胞提取物中共沉淀这两种蛋白质。这不是由于RNA聚合酶上两种蛋白质的存在。B的蛋白质印迹分析。通过凝胶过滤色谱法分级分离的枯草杆菌提取物显示出不与RNA聚合酶共沉淀的RsbW的单峰和σ（B）蛋白的两个峰：一个用RNA聚合酶洗脱，第二个与含有RsbW的级分重叠。进行重建实验，其中将部分纯化的sigma（B）和RsbW加入核心RNA聚合酶中，并测试它们在体外影响sigma（B）依赖性启动子（ctc）转录的能力。RsbW有效地阻断了sigma（B）依赖性转录，但仅当在加入核心酶之前与sigma（B）孵育时。
Sigma(B) is a secondary or factor of Bacillus subtilis. RNA polymerase containing sigma(B) transcribes a subset of genes that are expressed after heat shock or the onset of the stationary phase of growth. Three genes (rsbV, rsbW, and rsbX), cotranscribed with the sigma(B) structural gene (sigB), regulate sigma(B)-dependent gene expression. RsbW is the primary inhibitor of this system with the other gene products acting upstream of RsbW in the sigma(B) regulatory pathway. Evidence is now presented that RsbW inhibits sigma(B)-dependent transcription by binding to sigma(B) and blocking the formation of a sigma(B)-containing RNA polymerase holoenzyme. Antibodies specific for either RsbW or sigma(B) will coprecipitate both proteins from crude cell extracts. This is not due to the presence of both proteins on RNA polymerase. Western blot analysis of B. subtilis extracts that had been fractionated by gel-filtration chromatography revealed a single peak of RsbW that did not coelute with RNA polymerase and two peaks of sigma(B) protein: one that eluted with RNA polymerase and a second that overlapped the fractions that contained RsbW. Reconstitution experiments were performed in which partially purified sigma(B) and RsbW were added to core RNA polymerase and tested for their ability to influence the transcription of a sigma(B)-dependent promoter (ctc) in vitro. RsbW efficiently blocked sigma(B)-dependent transcription but only if it was incubated with sigma(B) prior to the addition of the core enzyme.