- Chlamydiae encode a family of proteins named the polymorphic membrane proteins, or Pmps, whose role in infection and pathogenesis is unclear. The Rockey Laboratory is studying polymorphic membrane protein expression in Chlamydia abortus, a zoonotic pathogen that causes abortions in ewes. C. abortus contains 18 pmp genes, some of which carry internal homopolymeric repeat sequences (poly-G) that may have a role in controlling protein expression within infected cells.
The goal of this project was to elucidate the role of Pmps in the pathogenesis of C. abortus by evaluating patterns of Pmp expression and of the length of a poly-G region within pmp13G. Previous research in the Rockey Laboratory showed a variation in Pmp13G expression and suggested that expression of the pmp13G gene is required under certain culture conditions and not in others. It was hypothesized that this variation was due to changes in culture conditions and may have been linked to the necessity of the pmp13G gene only under certain stages of growth or certain culture conditions. Our approach integrated PCR-based Sanger sequencing results with both qualitative and quantitative data collected via fluorescence microscopy.
A variation in the length of the poly-G region within pmp13G was demonstrated between C. abortus samples, and also between culture conditions via passaging of a single sample. Fluorescence microscopy showed Pmp18D was uniformly present among the strains analyzed, while detection of Pmp10G and Pmp13G differed between strains. Pmp13G presence was shown to vary between C. abortus strains, as well as between culture conditions via passaging of a single strain.
Key Words: Chlamydia abortus, polymorphic membrane protein, genomics