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Objective To investigate the function of general chaperones in the secretion of two-partner-secretion (TPS) protein across the inner membrane to the periplasm of Gram-negative bacteria. Methods The general chaperones were knocked-out and the strains were used to prepare spheroplast to see the effects on the secretion of FhaB*, which is a substrate of the representative model TPS substrates FhaB/FhaC system. Results Single knock-out of chaperones Skp,DegP,PpiD,YfgM and double knock-out of PpiD/YfgM has no or little effect on the secretion of FhaB* into the periplasm, while single knock-out of SurA or double knock-out of Skp/DegP severely affect the secretion of FhaB*. Conclusions There may be two molecular chaperone pathways mediated by SurA or by both SKP and DegP in Gram-negative bacteria, which can mediate the substrate protein of the two-partner-secretion system secretes into the peripheral space.

In order to explore the molecular function of Mig-14, we try to express Mig-14 and prepare the anti-Mig-14 polyclonal antibody. Codon preference analysis showed mig-14 gene contains 8% of rare codons. In this study, mig-14 was synthesized by considering the codon bias, GC cotent, restriction site et al. mig-14 in the periplasm which acquired by PCR using synthesized mig-14 as template was cloned into pET22b(+) and expressed in E. coli JM109. The recombinant protein Mig-14-p (Mig-14 in the periplasm) was purified by cutting the gel slices with KC1 stain and was used as antigen to prepare polyclonal antibody. This anti-Mig-14-p polyclonal antibody can be used to research the role of mig-14 in Salmonella enterica serovar Typhi. [ABSTRACT FROM AUTHOR]