MLPA, A LIPOPROTEIN REQUIRED FOR NORMAL DEVELOPMENT OF MYXOCOCCUS-XANTHUS

The mlpA gene encoding a 236-residue polypeptide has been identified i mmediately downstream of the oar gene of Myxococcus xanthus (Mt Martin ez-Canamero, J, Munoz-Dorado, E, Farez-Vidal, M, Inouye, and S, Inouye , J, Bacteriol, 175:4756-4763, 1993), The amino-terminal 21 residues o f MlpA encode a typical prokaryotic signal sequence with a putative li poprotein cleavage site, When expressed in Escherichia coli in the pre sence of [2-H-3] glycerol, H-3-labeled MlpA had a molecular mass of 33 kDa and was found to be associated with the membrane fraction, Globom ycin, an inhibitor of signal peptidase II, caused a shift in the mobil ity of E, coli-expressed MlpA to 35 kDa, Subsequently, a mlpA disrupti on strain (oar (+)) was constructed and found to have delayed fruiting body formation (by approximately 36 h), with significantly larger fru iting bodies being produced compared with those of the wild-type strai n, Nevertheless, spore yields for the two strains were identical after 120 h of development, These data indicate that MlpA, the lipoprotein identified in M, xanthus, is required for normal fruiting body formati on.