PSTI1可提高大肠杆菌应答胁迫能力

A novel STI1-like protein from Physarum polycephalum can enhance E.coli response to stress

指出含典型34肽重复序列结构域(tetratricopeptide repeat,TPR)的胁迫诱导蛋白(stress-in-ducible protein-1,STI1)是真核生物特有的一类与胁迫应答有关的分子伴侣蛋白.作者从多头绒泡菌分离出一个STI1类似蛋白cDNA,因其编码蛋白含有两个非典型的TPR结构域,命名为PSTI1.为了解PSTI1对原核生物胁迫应答功能的影响,观察表达PSTI1的大肠杆菌(Escherichia coli,E.coli)与原菌株的增殖差异,发现PSTI1表达菌耐受盐、渗透压、重金属离子、氧化、缺氧和酸碱变化胁迫的能力均增强,但对高温敏感.PSTI1保守结构域TPR1能提高E.coli耐受渗透压胁迫的能力,但TPR2会使E.coli对盐和渗透压胁迫敏感,说明TPR1和TPR2在PSTI1调控胁迫应答中可能扮演不同角色.通过pull-down和质谱分析技术检测了与PSTI1作用的E.coli蛋白,发现PSTI1能与E.coli的HtpG(Hsp90)、La蛋白酶和过氧化氢酶HpII等作用,说明PSTI1具有原核生物非典型TPR结构域蛋白的类似功能,是类似STI1的胁迫应答蛋白.

Stress-inducible protein-1（STI1） family members are conserved from human to yeast,functioning as adaptors to help client proteins to transfer from one heat shock protein to another in response to biologic and abiotic stress.A cDNA encoding 260 amino acids PSTI1 with homologue of STI1 was isolated from Physarum polycephalum,termed as PSTI1.This protein contains two atypical TPR domains.To determine the PSTI1 functions in protist response to stress,PSTI1 and its conserved peptides,TPR1 and TPR2,were expressed in E.coli OrigamiTM（DE3）.The interacted proteins with PSTI1 were detected and analyzed by pull-down and MALDI-TOF/TOF.The results indicate that the E.coli proteins obtained by PSTI1 pull-down include stress response proteins HtpG（a 90-KDa bacteria Heat shock protein）,catalase Hpii,protease La and metabolic proteins pyruvate dehydrogenase,etc.The growth of the recombinant E.coli under NaCl,sorbitol,CuSO4,H2O2,hypoxia,acid,alkali and temperature stress showed that PSTI1 expression could enhance E.coli resistance to the stress except temperature.TPR1 expression could enhance E.coli resistance to osmosis stress,while TPR2 expression could induce E.coli sensitive to salt and osmosis.The results of TPRI expression suggest that PSTI1 is widely involved in cellular response to diversity of stress.Its conserved domains TPR1 and TPR2 may play different roles on PSTI1 functions.