Weir J, Predich M, Dubnau E, Nair G, Smith I
Department of Microbiology, Public Health Research Institute, New York, New York.
J Bacteriol. 1991 Jan;173(2):521-9. doi: 10.1128/jb.173.2.521-529.1991.
The Bacillus spo0H gene codes for sigma H, which, as part of the RNA polymerase holoenzyme E sigma H, is responsible for the transcription of several genes which are expressed at the beginning of the sporulation process. In this communication, we examined the regulation of the spo0H gene of Bacillus subtilis by using lacZ reporter gene assays, quantitative RNA determinations, and Western immunoassay. The expression of the spo0H gene increases as the culture enters the mid-logarithmic stage of growth. This increased expression requires the genes spo0A, spo0B, spo0E, and spo0F, and the requirement for at least spo0A and spo0B can be bypassed when the abrB gene is mutated. The expression of the spo0H gene is constitutive in the presence of the abrB mutation, being expressed at higher levels during vegetative growth. In addition, the sof-1 mutation, in the spo0A structural gene, can bypass the need for spo0F in spo0H expression. The transcriptional start site of spo0H was determined by using RNA made in vivo as well as in vitro. These studies indicate that spo0H is transcribed by the major vegetative RNA polymerase, E sigma A. spo0H RNA and sigma H levels during growth are not identical to each other or to the pattern of expression of spoVG, a gene transcribed by E sigma H. This suggests that spo0H is regulated posttranscriptionally and also that factors in addition to sigma H levels are involved in the expression of genes of the E sigma H regulon.
芽孢杆菌的spo0H基因编码σH，它作为RNA聚合酶全酶EσH的一部分，负责在芽孢形成过程开始时表达的几个基因的转录。在本通讯中，我们通过使用lacZ报告基因检测、RNA定量测定和Western免疫测定来研究枯草芽孢杆菌spo0H基因的调控。spo0H基因的表达随着培养物进入对数生长中期而增加。这种表达增加需要spo0A、spo0B、spo0E和spo0F基因，当abrB基因发生突变时，至少对spo0A和spo0B的需求可以被绕过。spo0H基因的表达在存在abrB突变时是组成型的，在营养生长期间以更高水平表达。此外，spo0A结构基因中的sof-1突变可以绕过spo0H表达中对spo0F的需求。通过使用体内和体外合成的RNA确定了spo0H的转录起始位点。这些研究表明，spo0H由主要的营养RNA聚合酶EσA转录。生长期间spo0H RNA和σH水平彼此不同，也与由EσH转录的spoVG基因的表达模式不同。这表明spo0H在转录后受到调控，并且除了σH水平之外的因素也参与了EσH调控子基因的表达。
