MOLECULAR ANALYSIS OF THE P97 CILIUM ADHESIN OPERON OF MYCOPLASMA-HYOPNEUMONIAE

Mycoplasma hyopneumoniae causes an economically significant respirator y disease of swine called Enzootic Pneumonia. The disease process is i nitiated by adherence of M. hyopneumoniae to the cilia of swine respir atory epithelium through an interaction involving P97, a surface-assoc iated protein, and cilia-specific receptors. Binding specificity is as sociated with a repeat region located near the C-terminus of the P97 p rotein. Further analysis of the DNA sequences surrounding the P97 stru ctural gene revealed an operon composed of two ORFs, P97 and one codin g for a 102.3-kDa protein designated P102. Hybridization analysis and subcloning experiments showed that the P97 adhesin-encoding gene was p resent as a single copy in the M. hyopneumoniae chromosome. P102 seque nces, however, were found on four distinct chromosomal fragments, sugg esting that multiple copies of P102 were present in the chromosome. On e of these clones was identified by screening the genomic library with swine convalescent sera showing that P102 is expressed in vivo during M. hyopneumoniae infections. All copies of P102 were mapped to a sing le chromosomal region comprising approximately 13% of the genome (140 kb), although the exact distance between the copies is not known. The function of P102 is also not known, but the translated sequence shows a prominent transmembrane domain, suggesting that it may be a surface protein. (C) 1998 Elsevier Science B.V. All rights reserved.