Damron F Heath, Napper Jennifer, Teter M Allison, Yu Hongwei D
Department of Biochemistry and Microbiology, Joan C. Edwards School of Medicine at Marshall University, Huntington, WV 25755-9320, USA.
Department of Biology and Environmental Science, West Virginia Wesleyan College, Buckhannon, WV 26201, USA.
Microbiology (Reading). 2009 Apr;155(Pt 4):1028-1038. doi: 10.1099/mic.0.025833-0.
Chronic lung infection with P. aeruginosa and excessive neutrophil-associated inflammation are major causes of morbidity and mortality in patients with cystic fibrosis (CF). Overproduction of an exopolysaccharide known as alginate leads to the formation of mucoid biofilms that are resistant to antibiotics and host defences. Alginate overproduction or mucoidy is controlled by a stress-related ECF sigma factor AlgU/T. Mutation in the anti-sigma factor MucA is a known mechanism for conversion to mucoidy. Recently, we showed that inactivation of a kinase (KinB) in nonmucoid strain PAO1 results in overproduction of alginate. Here, we report the initial characterization of lipotoxin F (LptF, PA3692), an OmpA-like outer membrane protein that exhibited increased expression in the mucoid PAO1kinB mutant. The lipotoxin family of proteins has been previously shown to induce inflammation in lung epithelia, which may play a role in CF disease progression. Expression of LptF was observed to be AlgU-dependent and upregulated in CF isolates. Deletion of lptF from the kinB mutant had no effect on alginate production. Deletion of lptF from PAO1 caused a differential susceptibility to oxidants that can be generated by phagocytes. The lptF and algU mutants were more sensitive to hypochlorite than PAO1. However, the lptF mutant displayed increased resistance to hydrogen peroxide. LptF also contributed to adhesion to A549 human lung epithelial cells. Our data suggest that LptF is an outer membrane protein that may be important for P. aeruginosa survival in harsh environments, including lung colonization in CF.
铜绿假单胞菌引起的慢性肺部感染以及与中性粒细胞相关的过度炎症是囊性纤维化（CF）患者发病和死亡的主要原因。一种名为藻酸盐的胞外多糖过量产生会导致形成对抗生素和宿主防御具有抗性的黏液样生物膜。藻酸盐的过量产生或黏液样化由一种与应激相关的ECF σ因子AlgU/T控制。抗σ因子MucA的突变是转化为黏液样化的一种已知机制。最近，我们发现非黏液样菌株PAO1中的一种激酶（KinB）失活会导致藻酸盐过量产生。在此，我们报告脂毒素F（LptF，PA3692）的初步特征，它是一种类似OmpA的外膜蛋白，在黏液样PAO1kinB突变体中表达增加。先前已表明脂毒素蛋白家族可诱导肺上皮细胞炎症，这可能在CF疾病进展中起作用。观察到LptF的表达依赖于AlgU且在CF分离株中上调。从kinB突变体中缺失lptF对藻酸盐产生没有影响。从PAO1中缺失lptF导致对吞噬细胞可产生的氧化剂的敏感性存在差异。lptF和algU突变体比PAO1对次氯酸盐更敏感。然而，lptF突变体对过氧化氢表现出增强的抗性。LptF也有助于黏附到A549人肺上皮细胞。我们的数据表明LptF是一种外膜蛋白，可能对铜绿假单胞菌在恶劣环境中的存活很重要，包括在CF患者肺部定植。
