嗜麦芽寡养单胞菌SMP蛋白的胞外可调控分泌及序列分析

为了观察和探讨嗜麦芽寡养单胞菌SMP蛋白胞外可调控分泌现象及其机制,将收集到的环境株菌D2株及9株临床株在含不同成分的培养基中培养,取培养液上清利用SDS-PAGE电泳观察SMP蛋白分泌情况;提取各菌株基因组DNA,PCR扩增其smp基因并进行克隆和序列测定;将获得的SMP氨基酸序列用Blastp、Megalign等进行分析,并构建系统发育树。结果显示,不同来源的嗜麦芽寡养单胞菌胞SMP蛋白分泌均存在可调控现象,酵母提取物可抑制该蛋白的分泌,而适宜浓度的麦芽糖则具有促进作用。序列对比及系统发育树分析显示,SMP的氨基酸序列具有种属的特异性,且临床株和环境株中存在一定的差异,临床株中该蛋白的氨基酸序列高度保守,而环境株则序列差异相对明显的,但不同来源的菌株SMP均含有保守的信号肽;提示该蛋白可能与其致病性相关,其胞外分泌的可调控机制值得进一步深入探究。

Extracellular Regulatable Secretion and Sequence Analysis of SMP Protein of Stenotrophomonas maltophilia

In order to observe and investigate the regulatable SMP protein extracellular secretion phenomenon and its mechanism in Stenotrophomonas maltophilia, environmental strain D2 and nine strains collected from clinic were cultured in media containing different ingredients. The secretion of SMP protein in supernatant was observed using SDS-PAGE. The smp gene was amplified from genomes extracted from all strains. PCR products were cloned and sequenced to analyze amino acid sequences of SMP with Blastp and Megalign etc, and build phylogeny tree. The results showed that SMP secretion from different sources of S. maltophillia all have regulatable phenomenon. Yeast extract can inhibit the secretion of SMP protein and maltose of suitable concentration possessed enhancement. Amino acid sequence comparison and phylogenetic tree analysis showed that amino acid sequence of SMP has species specificity, and there are a certain differences between clinical and environmental strains. The amino acid sequence of SMP protein was highly conserved, while the difference was relatively significant in environmental strains. However, SMP of strains from different sources contains conserved signal peptide; Suggested that SMP protein probably correlated to the pathogenicity of the protein. The regulatable mechanism of SMP secretion is worthy for further deepening study.