Marraffini Luciano A, Schneewind Olaf
Department of Microbiology, University of Chicago, 920 East 58th Street, Chicago, IL 60637, USA.
Mol Microbiol. 2006 Dec;62(5):1402-17. doi: 10.1111/j.1365-2958.2006.05469.x. Epub 2006 Oct 27.
Dormant spores of Bacillus anthracis germinate during host infection and their vegetative growth and dissemination precipitate anthrax disease. Upon host death, bacilli engage a developmental programme to generate infectious spores within carcasses. Hallmark of sporulation in Bacillus spp. is the formation of an asymmetric division septum between mother cell and forespore compartments. We show here that sortase C (SrtC) cleaves the LPNTA sorting signal of BasH and BasI, thereby targeting both polypeptides to the cell wall of sporulating bacilli. Sortase substrates are initially produced in different cell compartments and at different developmental stages but penultimately decorate the envelope of the maturing spore. srtC mutants appear to display no defect during the initial stages of infection and precipitate lethal anthrax disease in guinea pigs at a similar rate as wild-type B. anthracis strain Ames. Unlike wild-type bacilli, srtC mutants do not readily form spores in guinea pig tissue or sheep blood unless their vegetative forms are exposed to air.
炭疽芽孢杆菌的休眠孢子在宿主感染期间萌发，其营养生长和传播会引发炭疽病。宿主死亡后，杆菌进入一个发育程序，在尸体内部产生感染性孢子。芽孢杆菌属中孢子形成的标志是在母细胞和前芽孢区室之间形成不对称分裂隔膜。我们在此表明，分选酶C（SrtC）切割BasH和BasI的LPNTA分选信号，从而将这两种多肽靶向到正在形成孢子的杆菌的细胞壁。分选酶底物最初在不同的细胞区室和不同的发育阶段产生，但最终会修饰成熟孢子的包膜。srtC突变体在感染初期似乎没有表现出缺陷，并且在豚鼠中引发致命炭疽病的速度与野生型炭疽芽孢杆菌菌株Ames相似。与野生型杆菌不同，srtC突变体在豚鼠组织或羊血中不容易形成孢子，除非它们的营养形式暴露在空气中。
