Akiyama Takuya, Inouye Sumiko, Komano Teruya
Department of Biology, Tokyo Metropolitan University, Minamiohsawa, Hachioji, Tokyo 192-0397, Japan.
J Bacteriol. 2003 Jun;185(11):3317-24. doi: 10.1128/JB.185.11.3317-3324.2003.
Myxococcus xanthus is a gram-negative soil bacterium that undergoes multicellular development upon nutrient starvation. In the present study, two novel developmental genes, fruC and fruD, of M. xanthus were identified and characterized. The FruD protein has significant amino acid sequence similarity to the DivIVA proteins of many bacteria including Bacillus subtilis. Vegetative cells of the fruD mutant exhibited a filamentous phenotype. The fruC and fruD mutants displayed similar delayed-development phenotypes. The formation of tightly aggregated mounds by fruC and fruD mutants was slower than that by the wild-type strain. Spore formation by the fruC and fruD mutants initiated after 30 h poststarvation, whereas wild-type M. xanthus initiated spore formation after 18 h. The fruCD genes were constitutively expressed as an operon during vegetative growth and development. S1 mapping revealed that transcription initiation sites of the fruCD operon were located 114 (P1) and 55 bp (P2) upstream of the fruC initiation codon. Only the P1 promoter was active during vegetative growth, while both the P1 and P2 promoters were active during development. The FruD protein was produced as a cytoplasmic protein and formed an oligomer during vegetative growth and development.
黄色粘球菌是一种革兰氏阴性土壤细菌，在营养饥饿时会进行多细胞发育。在本研究中，鉴定并表征了黄色粘球菌的两个新的发育基因fruC和fruD。FruD蛋白与包括枯草芽孢杆菌在内的许多细菌的DivIVA蛋白具有显著的氨基酸序列相似性。fruD突变体的营养细胞表现出丝状表型。fruC和fruD突变体表现出相似的发育延迟表型。fruC和fruD突变体形成紧密聚集的菌丘的速度比野生型菌株慢。fruC和fruD突变体在饥饿30小时后开始形成孢子，而野生型黄色粘球菌在18小时后开始形成孢子。fruCD基因在营养生长和发育过程中作为一个操纵子组成型表达。S1图谱分析表明，fruCD操纵子的转录起始位点位于fruC起始密码子上游114（P1）和55 bp（P2）处。只有P1启动子在营养生长期间活跃，而P1和P2启动子在发育期间均活跃。FruD蛋白作为一种细胞质蛋白产生，并在营养生长和发育过程中形成寡聚体。
