Early Development in Myxococcus xanthus.

摘要

The soil bacterium Myxococcus xanthus initiates a complex developmental program in response to amino acid starvation that requires coordination and communication between an entire colony, resulting in the formation of a three-dimensional fruiting body surrounding and supporting a differentiated population of environmentally resistant myxospores. Development is a highly regulated process and has been a major area of study since the beginning of research in the organism. The work presented in this dissertation investigates M. xanthus development from two different angles. In the first, genomic and gene expression data is used to predict developmentally-important response regulators. Deletion analysis of 16 candidate response regulators identified eight which are necessary for development and have not been previously reported in the literature. Most of the regulators appear to be responsible for the proper timing of developmental events based on mutant phenotypic analysis. In the second study, investigation of a rare Arginine kinase (AK) has demonstrated its role in development. Arginine kinase is typically found in eukaryotic organisms; only five bacteria are known to possess a homolog, and only one of those has been demonstrated to have kinase function. M. xanthus AK was purified and demonstrated the ability to phosphorylate arginine. Deletion analysis identified AK as necessary for proper development, especially under more stringent fast starvation modes, potentially due to energy buffering effects common to AKs in other species. This is the first demonstration of a physiological role for AK in a bacterium.