Arcuri Edna F, Wiedmann Martin, Boor Kathryn J
Food Science Department, Cornell University, Ithaca, NY 14853, USA1.
Microbiology (Reading). 2000 Jul;146 ( Pt 7):1593-1603. doi: 10.1099/00221287-146-7-1593.
Conservation of the sporulation processes between Bacillus spp. and Clostridium spp. was investigated through evolutionary and complementation analyses of sigma(E). Alignment of partial predicted sigma(E) amino acid sequences from three Bacillus spp., Paenibacillus polymyxa and five Clostridium spp. revealed that amino acid residues previously reported to be involved in promoter utilization (M124, E119 and N120) and strand opening (C117) are conserved among all these species. Phylogenetic analyses of various sigma factor sequences from endospore-forming bacteria revealed that homologues of sigma(E), sigma(K) and sigma(G) clustered together regardless of genus, suggesting a common origin of sporulation sigma factors. The functional equivalence between Clostridium acetobutylicum sigma(E) and Bacillus subtilis sigma(E) was investigated by complementing a non-polar B. subtilis sigma(E) null mutant with the spoIIG operon from either B. subtilis (spoIIG(Bs)) or C. acetobutylicum (spoIIG(Ca)). Single-copy integration of spoIIG(Bs) into the amyE locus of the sigma(E) null mutant completely restored the wild-type sporulation phenotype, while spoIIG(Ca) only partially restored sporulation. Maximal expression of spoIIG(Ca)-lacZ occurred approximately 12 h later than maximal expression of spoIIG(Bs)-lacZ. Differences in temporal expression patterns for spoIIG(Ca) and spoIIG(Bs) in the B. subtilis background may at least partially explain the observed sporulation complementation phenotypes. This study suggests a common phylogenetic ancestor for sigma(E) in Bacillus spp. and Clostridium spp., although regulation of sigma(E) expression may differ in these two genera.
通过对σ(E)进行进化分析和互补分析，研究了芽孢杆菌属和梭菌属之间孢子形成过程的保守性。对三种芽孢杆菌属、多粘类芽孢杆菌和五种梭菌属的部分预测σ(E)氨基酸序列进行比对，结果显示，先前报道的参与启动子利用（M124、E119和N120）和链打开（C117）的氨基酸残基在所有这些物种中都是保守的。对来自产芽孢细菌的各种σ因子序列进行系统发育分析，结果表明，σ(E)、σ(K)和σ(G)的同源物无论属别都聚集在一起，这表明孢子形成σ因子有共同的起源。通过用枯草芽孢杆菌（spoIIG(Bs)）或丙酮丁醇梭菌（spoIIG(Ca)）的spoIIG操纵子对非极性枯草芽孢杆菌σ(E)缺失突变体进行互补，研究了丙酮丁醇梭菌σ(E)和枯草芽孢杆菌σ(E)之间的功能等效性。将spoIIG(Bs)单拷贝整合到σ(E)缺失突变体的amyE位点，完全恢复了野生型孢子形成表型，而spoIIG(Ca)仅部分恢复了孢子形成。spoIIG(Ca)-lacZ的最大表达比spoIIG(Bs)-lacZ的最大表达大约晚12小时。spoIIG(Ca)和spoIIG(Bs)在枯草芽孢杆菌背景中的时间表达模式差异可能至少部分解释了观察到的孢子形成互补表型。这项研究表明芽孢杆菌属和梭菌属中的σ(E)有共同的系统发育祖先，尽管这两个属中σ(E)表达的调控可能有所不同。
