IDENTIFICATION OF ESG, A GENETIC-LOCUS INVOLVED IN CELL-CELL SIGNALING DURING MYXOCOCCUS-XANTHUS DEVELOPMENT

JD258, a Tn5 insertion mutant of Myxococcus xanthus, was shown to have major defects in three development-associated properties: expression of the developmentally regulated tps gene, spore formation, and produc tion of multicellular fruiting bodies. The defects in tps gene express ion and sporulation could be substantially corrected, at the phenotypi c level, by mixing JD258 with wild-type cells (extracellular complemen tation). By this criterion, JD258 appeared to be a new member of a gro up of conditional developmental mutants that were previously character ized and placed in four extracellular complementation groups (A to D) based on the ability of mutants in one group to stimulate development in mutants belonging to a different group (D. C. Hagen, A. P. Bretsche r, and D. Kaiser, Dev. Biol. 64:284-296, 1978). Mutants from groups A, B, C, and D all displayed extracellular complementation activity when mixed with JD258. These results, and other aspects of the phenotype o f JD258, indicate that this mutant defines a fifth extracellular compl ementation group, group E. The M. xanthus esg locus identified by the Tn5 insertion in JD258 was cloned in Escherichia coli and used for fur ther genetic analysis of the locus. These studies indicated that the e sg locus resides within a 2.5-kb region of the M. xanthus chromosome a nd that the locus contains at least two genetic complementation groups . Our results are consistent with a model in which the esg locus contr ols the production of a previously unrecognized extracellular signal t hat must be transmitted between cells for the completion of M. xanthus development.