Koch Birgit, Nybroe Ole
Genetics and Microbiology Group, Department of Ecology, The Royal Veterinary and Agricultural University, Frederiksberg C, Copenhagen, Denmark.
FEMS Microbiol Lett. 2006 Sep;262(1):48-56. doi: 10.1111/j.1574-6968.2006.00359.x.
The RpoS-regulated bolA gene in Escherichia coli is important for the decrease in cell size during stationary phase or sudden carbon starvation. A Pseudomonas fluorescens strain mutated in a gene with homology to bolA reduced its cell size upon carbon starvation, and RpoS had little effect on bolA expression. The mutant grew slower than the wild-type strain in minimal medium with L-serine as the sole nitrogen source, while growth rates were similar on a mixture of L-serine and L-cysteine. Reverse transcriptase polymerase chain reaction analysis indicated that the bolA homologue is the second gene in an operon where the two next ORFs encode putative proteins with homology to sulphurtransferases and protein disulphide isomerases. Complementation of the mutant phenotypes was only obtained by plasmids encoding BolA as well as the above two proteins. Growth phenotypes and gene homologies suggest that BolA-like proteins have different functions in E. coli and Pseudomonas.
大肠杆菌中受RpoS调控的bolA基因对于稳定期或突然碳饥饿期间细胞大小的减小很重要。荧光假单胞菌中一个与bolA具有同源性的基因突变菌株在碳饥饿时细胞大小减小，且RpoS对bolA的表达影响很小。在以L-丝氨酸作为唯一氮源的基本培养基中，该突变体比野生型菌株生长得慢，而在L-丝氨酸和L-半胱氨酸的混合物上生长速率相似。逆转录聚合酶链反应分析表明，bolA同源物是一个操纵子中的第二个基因，该操纵子中的另外两个开放阅读框编码与硫转移酶和蛋白质二硫键异构酶具有同源性的推定蛋白质。只有通过编码BolA以及上述两种蛋白质的质粒才能实现突变体表型的互补。生长表型和基因同源性表明，BolA样蛋白在大肠杆菌和假单胞菌中具有不同的功能。
