Bourne N, FitzJames P C, Aronson A I
Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907.
J Bacteriol. 1991 Oct;173(20):6618-25. doi: 10.1128/jb.173.20.6618-6625.1991.
The start sites for transcription and translation of a Bacillus subtilis spore coat protein gene, cotT, were determined. The CotT protein was synthesized as a 10.1-kDa precursor which was processed to a coat polypeptide of 7.8 kDa. Insertional inactivation of the cotT gene resulted in spores with an altered appearance of the inner coat layers and slow germination in response to a germination solution containing fructose, glucose, and asparagine. Rates of germination in L-alanine and in Penassay broth were the same as that of the wild type. A strain containing the cotT gene on a low-copy-number plasmid produced spores with an excess of CotT precursor and a thickening of the striated inner coat. These spores responded poorly to all of the germinants mentioned above. A site-directed mutation of the codon at the processing site of CotT resulted in the accumulation of the precursor in sporulating cells and on the spores, but there was no effect on the germination rates or solvent resistance of these spores. Both the lack and the overproduction of CotT led to subtle alterations in the structure of the inner spore coat and in the capacity of spores to respond to particular germinants.
确定了枯草芽孢杆菌芽孢衣壳蛋白基因cotT的转录和翻译起始位点。CotT蛋白最初以10.1 kDa的前体形式合成，随后加工成7.8 kDa的衣壳多肽。cotT基因的插入失活导致芽孢的内皮层外观改变，并且在含有果糖、葡萄糖和天冬酰胺的萌发液中萌发缓慢。在L-丙氨酸和检测肉汤中的萌发率与野生型相同。一个在低拷贝数质粒上携带cotT基因的菌株产生的芽孢含有过量的CotT前体，并且条纹状内皮层增厚。这些芽孢对上述所有萌发剂的反应都很差。CotT加工位点处密码子的定点突变导致前体在芽孢形成细胞和芽孢上积累，但对这些芽孢的萌发率或耐溶剂性没有影响。CotT的缺乏和过量产生都会导致内芽孢衣壳结构的细微变化以及芽孢对特定萌发剂反应能力的变化。
