MOLECULAR-CLONING AND CHARACTERIZATION OF AN ADHERENCE-RELATED OPERONOF MYCOPLASMA-GENITALIUM

Adhesins and adhesin-related accessory proteins of pathogenic mycoplas mas are required for cytadherence and the subsequent development of di sease pathology. The classic example has been Mycoplasma pneumonine, w hich causes primary atypical pneumonia in humans. Mutants of M. pneumo niae defective in adhesins (P1 and P30) or in adherence-accessory prot eins (HMW1 through HMW4) are unable to colonize host tissues and are a virulent. Mycoplasma genitalium, implicated in nongonococcal, nonchlam ydial urethritis, pneumonia, arthritis, and AIDS progression, was foun d to encode a 140-kDa adhesin that shared both DNA and protein sequenc e similarities with P1, a major adhesin of M. pneumoniae. In this repo rt, we show that M. genitalium possesses additional homolog sequences to well-characterized adherence-related genes and proteins of M. pneum oniae. The M. genitalium homologs are designated P32 and P69 and corre spond to P30 and HMW3 of M. pneumoniae, respectively (J. B. Baseman, p . 243-259, in S. Rottem and I. Kahane, ed., Subcellular biochemisay, v ol. 20. Mycoplasma cell membranes, 1993, and D. C. Krause, D. K. Leith , R. M. Wilson, and J. B. Baseman, Infect. Immun. 35:809-817, 1982). I nterestingly, the operon-like organizations of P32 and P69 in the M. g enitalium genome are similar to the organizations of P30 and HMW3 gene s of M. pneumoniae, suggesting that the conservation of these adherenc e related genes and proteins might have occurred through horizontal ge ne transfer events originating from an ancestral gene family.