Chlamydia Genomic MinD Protein Has not the Function of Regulating Plasmid-dependent Genes as Pgp5

Abstract

Chlamydia has a unique intracellular developmental cycle which has hindered the function study of Chlamydia. Transformation system of Chlamydia developed recently has greatly advanced the chlamydial function research and has been used to find chlamydial plasmid-encoded pgp5 can down-regulate plasmid-dependent genes. It is predicted that pgp5 has similar function with MinD protein encoded by chlamydial genome. However，it is unknown whether MinD has the function of regulating these plasmid-dependent genes. The pgp5 gene in the shuttle vector pGFP::CM was replaced with MinD gene of Chlamydia trachomatis (CT0582) or Chlamydia muridarum(TC0871). The recombinant plasmid was transformed into plasmid-free organisms-CMUT3.Real time PCR was used to detect the genes transcription level in these pgp5 replacement organisms. GlgA, one of the plasmid-regulated gene products was detected by the immunofluorescence assay. After recombination, transformation and plaque purification, the stable transformants CMUT3-pGFP::CM CT0582Rpgp5 and CMUT3-pGFP::CM TC0871Rpgp5 were generated. In these transformants, the plasmid-dependent genes were up-regulated, similar with those in the pgp5 premature stop mutant and pgp5 replacement with mCherry mutant. GlgA protein was also increased in all pgp5 mutants including CT0582Rpgp5 and TC0871Rpgp5. Thus, the transformation system has allowed us to identify the function of MinD that is useful for further understanding the chlamydiae.