Molecular cloning of a Coxiella burnetii gene encoding a macrophage infectivity potentiator (Mip) analogue

Y. Y. Mo, N. P. Cianciotto, L. P. Mallavia*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

49 Scopus citations


The gene encoding a protein that reacted with antibodies specific for Legionella pneumophila macrophage infectivity potentiator (LpMip) was cloned from Coxiella burnetii, the obligate intracellular rickettsia that causes Q fever in humans. Nucleotide sequencing analysis revealed an ORF encoding a gene product of 230 amino acids with a molecular mass of 25.5 kDa and a predicted pi of 10.7. The predicted amino acid sequence from the ORF shows similarity with Mip/Mip-like proteins of Legionella (46%) and Chlamydia (30%). Moreover, like LpMip, the amino acid sequence of the C terminus of this protein has over 35% identity to prokaryotic and eukaryotic FK506-binding proteins (FKBPs) that belong to a superfamily of immunophilins and are peptidyl-prolyl cis-trans isomerases (PPIases). When overproduced in Escherichia coli, the C. burnetii protein also exhibited PPIase activity. Taken together, these results demonstrate that C. burnetii encodes a Mip analogue (CbMip). A putative leader peptide at the N terminus of CbMip was detected by computer analysis. Furthermore, TnphoA mutagenesis demonstrated that in E. coli CbMip was secreted. In view of the role of Mip/Mip-like proteins in the pathogenesis of Legionella and Chlamydia, CbMip may be a C. burnetii virulence factor.

Original languageEnglish (US)
Pages (from-to)2861-2871
Number of pages11
Issue number11
StatePublished - 1995


  • Coxiella burnetii
  • Mip
  • Virulence factor

ASJC Scopus subject areas

  • Microbiology


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