Khan Rasel, Takahashi Eizo, Ramamurthy Thandavarayan, Takeda Yoshifumi, Okamoto Keinosuke
Laboratory of Protein Function, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama 700-8530, Japan.
Microbiol Immunol. 2007;51(10):963-76. doi: 10.1111/j.1348-0421.2007.tb03993.x.
Previously we have shown that the open reading frame 2 protein (ORF2 protein), which is encoded at the 3 ' end of serine protease of Aeromonas sobria (ASP), functions as a chaperone protein in periplasm in the production of ASP. Both proteins, ASP and ORF2 protein, associate in periplasm and ORF2 protein helps ASP to take an active form. ASP which is dissociated from ORF2 protein emerges in milieu . In this study, we examined the effect of sodium chloride (NaCl) in medium on ASP production by A. sobria. The ASP activity of culture supernatant was extremely decreased when A. sobria was cultured in medium containing 3.0% NaCl (concentration almost equivalent to sea water salinity). Our analysis showed that the transcription of asp by A. sobria is not inhibited by NaCl in medium and that A. sobria synthesizes and releases ASP in milieu even under the condition of 3.0% NaCl. However, these ASPs in milieu formed complex as with ORF2 proteins. This indicates that the maturation pathway of ASP is disturbed in A. sobria cultured in medium containing 3.0% NaCl. It is likely that ASP does not associate with ORF2 protein in the correct form in periplasam when A. sobria is cultured in medium containing 3.0% NaCl, though both proteins, ASP and ORF2 protein, make complexes and emerge outside of the cell. This idea suggests that the chaperone system of ASP possesses the ability to sense NaCl in surroundings and regulates the production of active ASP.
此前我们已经表明，嗜水气单胞菌丝氨酸蛋白酶（ASP）3' 端编码的开放阅读框2蛋白（ORF2蛋白）在ASP产生过程中作为周质中的伴侣蛋白发挥作用。ASP和ORF2蛋白这两种蛋白在周质中结合，ORF2蛋白帮助ASP形成活性形式。与ORF2蛋白解离的ASP出现在周围环境中。在本研究中，我们检测了培养基中的氯化钠（NaCl）对嗜水气单胞菌产生ASP的影响。当嗜水气单胞菌在含有3.0% NaCl（浓度几乎等同于海水盐度）的培养基中培养时，培养上清液的ASP活性极度降低。我们的分析表明，嗜水气单胞菌中asp的转录不受培养基中NaCl的抑制，并且即使在3.0% NaCl的条件下，嗜水气单胞菌仍能在周围环境中合成并释放ASP。然而，这些周围环境中的ASP与ORF2蛋白形成了复合物。这表明在含有3.0% NaCl的培养基中培养的嗜水气单胞菌中，ASP的成熟途径受到了干扰。当嗜水气单胞菌在含有3.0% NaCl的培养基中培养时，尽管ASP和ORF2蛋白这两种蛋白形成复合物并出现在细胞外，但ASP可能无法在周质中以正确的形式与ORF2蛋白结合。这一观点表明，ASP的伴侣系统具有感知周围环境中NaCl的能力，并调节活性ASP的产生。
