Characterization of asgC, a Gene Required for Cell-Cell Signaling in Myxococcus xanthus

摘要

Myxococcus xandus is a soil bacterium that forms spore-filled fruiting bodies in response to nutrient imitation coupled with high cell density. Extracellular A-signal, which is composed of amino acids and peptides, is produced during early development and is thought to function as a cell density signal. The asgC gene is one of three known regulatory genes that are required for A-signal production. The asgA and asgB genes encode a signaling kinase and a putative transcription factor, respectively. The goal of this project is to understand the role of asgC In A-signal production. To this end, the DNA sequence of asgC and the only known asgC mutant allele, asgC767, was determined. The asgC gene encodes RpoD, the major sigma factor in M. xandius. The second aim is to isolate pseudorevertants of asgC767 that have regained the ability to produce fruiting bodies and extracellular A-signal Approximately 40 independent pseudorevertants have been isolated, and their characterization has been initiated Analysis of these mutants may lead to the identification of additional components of the signal transduction pathway leading to A-signal production. In addition, we are exploring the role of AsgC in expression of CELA, a gene encoding an extracellular endoglucanase.