Barák I, Behari J, Olmedo G, Guzmán P, Brown D P, Castro E, Walker D, Westpheling J, Youngman P
Department of Genetics, University of Georgia, Athens 30602, USA.
Mol Microbiol. 1996 Mar;19(5):1047-60. doi: 10.1046/j.1365-2958.1996.433963.x.
Functioning of the spoIIE locus of Bacillus subtilis is required for formation of a normal polar septum during sporulation and for activation of the transcription factor sigma F, which directs early forespore-specific gene expression. We have determined the DNA sequence of the wild type and several mutant alleles of the spoIIE gene of B. subtilis and sequenced a substantial portion of its presumptive homologue in Bacillus megaterium. We show that the spoIIE locus encodes a single large protein with a predicted molecular mass of 92 kDa. Each of five point-mutation alleles, which have traditionally defined the locus, and two transposon-generated mutations were shown to fall within the coding sequence for the 92 kDa gene product or within sequences expected to be required for its expression. The amino-terminal portion of the predicted SpoIIE gene product, comprising approximately 40% of the protein, is extremely hydrophobic and is expected to contain up to 12 membrane-spanning segments. The remainder of the protein contains no hydrophobic segments long enough to span a lipid bilayer and is therefore presumed to comprise one or more globular, aqueous-phase exposed domains. An in-frame fusion joining the 3' end of the B. megaterium spoIIE coding sequence to the 5' end of gfp, a gene encoding the green fluorescent protein (GFP) of Aquorea victoria, resulted in a strong, sporulation-specific fluorescent signal localized to the sites of sporulation septum assembly. We speculate that SpoIIE plays a role in assembling the sporulation septum, perhaps determining the special properties of the structure that permit intercompartment signalling during development.
枯草芽孢杆菌spoIIE基因座的功能对于芽孢形成过程中正常极性隔膜的形成以及转录因子σF的激活是必需的，σF指导早期前芽孢特异性基因的表达。我们已经确定了枯草芽孢杆菌spoIIE基因的野生型和几个突变等位基因的DNA序列，并对巨大芽孢杆菌中其假定同源物的大部分进行了测序。我们表明，spoIIE基因座编码一种单一的大蛋白，预测分子量为92 kDa。传统上定义该基因座的五个点突变等位基因中的每一个，以及两个转座子产生的突变，都被证明位于92 kDa基因产物的编码序列内或其表达所需的序列内。预测的SpoIIE基因产物的氨基末端部分，约占该蛋白的40%，具有极强的疏水性，预计包含多达12个跨膜区段。该蛋白的其余部分不包含足够长的疏水区段以跨越脂质双层，因此推测其包含一个或多个球状的、暴露于水相的结构域。将巨大芽孢杆菌spoIIE编码序列的3'末端与gfp（编码维多利亚水母绿色荧光蛋白（GFP）的基因）的5'末端进行读码框内融合，产生了一个强烈的、芽孢形成特异性荧光信号，定位于芽孢形成隔膜组装的部位。我们推测SpoIIE在芽孢形成隔膜的组装中起作用，也许决定了该结构在发育过程中允许隔室间信号传递的特殊性质。
