The Vision Co-operative Research Centre, Sydney, Australia.
School of Optometry and Vision Science, University of New South Wales, Sydney, Australia.
J Med Microbiol. 2012 Feb;61(Pt 2):180-190. doi: 10.1099/jmm.0.034561-0. Epub 2011 Sep 15.
Expression of protease IV by Pseudomonas aeruginosa during ocular infections contributes significantly to tissue damage. However, several P. aeruginosa strains isolated from ocular infections or inflammatory events produce very low levels of protease IV. The aim of the present study was to characterize, genetically and phenotypically, the presence and expression of the protease IV gene in a group of clinical isolates that cause adverse ocular events of varying degrees, and to elucidate the possible control mechanisms of expression associated with this virulence factor. Protease IV gene sequences from seven clinical isolates of P. aeruginosa were determined and compared to P. aeruginosa strains PAO1 and PA103-29. Production and enzyme activity of protease IV were measured in test strains and compared to that of quorum-sensing gene (lasRI) mutants and the expression of other virulence factors. Protease IV gene sequence similarities between the isolates were 97.5-99.5 %. The strains were classified into two distinct phylogenetic groups that correlated with the presence of exo-enzymes from type three secretion systems (TTSS). Protease IV concentrations produced by PAOΔlasRI mutants and the two clinical isolates with a lasRI gene deficiency were restored to levels comparable to strain PAO1 following complementation of the quorum-sensing gene deficiencies. The protease IV gene is highly conserved in P. aeruginosa clinical isolates that cause a range of adverse ocular events. Observed variations within the gene sequence appear to correlate with presence of specific TTSS genes. Protease IV expression was shown to be regulated by the Las quorum-sensing system.
铜绿假单胞菌在眼部感染过程中表达蛋白酶 IV 会导致组织损伤。然而，从眼部感染或炎症事件中分离出的几种铜绿假单胞菌菌株产生的蛋白酶 IV 水平非常低。本研究的目的是从一组引起不同程度眼部不良事件的临床分离株中，从遗传和表型上对蛋白酶 IV 基因的存在和表达进行特征分析，并阐明与该毒力因子相关的表达的可能调控机制。测定了 7 株铜绿假单胞菌临床分离株的蛋白酶 IV 基因序列，并与铜绿假单胞菌 PAO1 和 PA103-29 株进行比较。在测试菌株中测量了蛋白酶 IV 的产生和酶活性，并与群体感应基因（lasRI）突变体和其他毒力因子的表达进行了比较。分离株之间蛋白酶 IV 基因序列的相似性为 97.5-99.5%。这些菌株分为两个不同的系统发育群，与 III 型分泌系统（TTSS）的外酶的存在相关。PAOΔlasRI 突变体和 lasRI 基因缺失的两个临床分离株产生的蛋白酶 IV 浓度在补充群体感应基因缺失后恢复到与 PAO1 菌株相当的水平。引起一系列眼部不良事件的铜绿假单胞菌临床分离株中蛋白酶 IV 基因高度保守。基因序列内观察到的变异似乎与特定 TTSS 基因的存在相关。蛋白酶 IV 的表达受 Las 群体感应系统的调控。
