Curiel-Quesada E, Setlow P
J Bacteriol. 1984 Mar;157(3):751-7. doi: 10.1128/jb.157.3.751-757.1984.
Three EcoRI fragments of Bacillus megaterium DNA hybridized only under nonrestrictive conditions on Southern blots to a probe containing the previously cloned gene for protein C, a small, acid-soluble spore protein (SASP) from B. megaterium. All three fragments were cloned in Escherichia coli cells in plasmid pBR325, and after being transferred to an E. coli expression vector, one of the fragments (C-3) directed the synthesis of a new small, acid-soluble spore protein (termed C-3) immunologically related to protein C. As previously observed with the protein C gene, protein C-3 gene expression in E. coli required an external promoter and suppression of termination of transcription. Protein C-3 was purified from induced E. coli cells, and its immunological properties, electrophoretic mobility, amino acid composition, and amino-terminal sequence were determined. These data indicated that protein C-3 was related, but not identical, to either protein C or the closely related protein A--two of the major small, acid-soluble spore proteins of B. megaterium. Detailed examination of acid extracts of B. megaterium spores showed that they contained a minor protein which comigrated with C-3 on acrylamide gel electrophoresis at low pH and reacted immunologically like C-3.
巨大芽孢杆菌DNA的三个EcoRI片段，仅在非严格条件下于Southern印迹上与一个含有先前克隆的蛋白C基因的探针杂交，蛋白C是一种来自巨大芽孢杆菌的小的、酸溶性芽孢蛋白（SASP）。所有这三个片段都克隆于大肠杆菌细胞的质粒pBR325中，在转移至大肠杆菌表达载体后，其中一个片段（C-3）指导合成了一种新的小的、酸溶性芽孢蛋白（称为C-3），它与蛋白C在免疫学上相关。正如先前在蛋白C基因中观察到的那样，蛋白C-3基因在大肠杆菌中的表达需要一个外部启动子并抑制转录终止。蛋白C-3从诱导的大肠杆菌细胞中纯化出来，并测定了其免疫学特性、电泳迁移率、氨基酸组成和氨基末端序列。这些数据表明，蛋白C-3与蛋白C或密切相关的蛋白A相关，但并不相同，蛋白A是巨大芽孢杆菌的两种主要的小的、酸溶性芽孢蛋白。对巨大芽孢杆菌芽孢的酸提取物进行的详细检查表明，它们含有一种次要蛋白，该蛋白在低pH下于丙烯酰胺凝胶电泳上与C-3迁移率相同，并且在免疫学上的反应与C-3相似。
