Regulation of M. xanthus Social Gliding by Dif Pathway

Virginia Polytechnic Institute And State University, Blacksburg VA

Investigators

Abstract

Myxococcus xanthus exhibits the most spectacular morphogenesis among bacteria during its developmental life cycle. In response to starvation, tens of thousands of cells move by gliding motility to aggregate and to form multicellular fruiting bodies visible to the naked eye. Vegetative cells within mature fruiting bodies differentiate into dormant and stress-resistant myxospores. Distinct from any other known gliding bacteria, M. xanthus possesses two gliding systems, the adventurous (A) and the social (S) motility systems. While A motility enables M. xanthus cells to move as isolated individuals, S motility is manifested as movement of large cell groups. It remains an enigma how M. xanthus cells interact and coordinate with one another to bring about S motility. A new set of genes, the dif genes, is implicated in S motility. The predicted dif gene products show high similarity to chemotaxis proteins from many bacteria. It is known that bacterial chemotaxis proteins constitute sensory signal transduction pathways that are responsible for bacterial tactic responses to environmental stimuli. The similarity between Dif and chemotaxis proteins and the S-motility defects of dif mutants strongly suggest the involvement of a sensory component in the regulation of S-motility. This project takes a multidisciplinary approach of genetics, molecular biology and biochemistry to examine and to consolidate working hypotheses. dif mutations will be constructed for functional and structural studies. Genetic suppressors of difA mutants will be characterized to identify genes with functional, biochemical and/or physical interactions with the dif chemotaxis-like signal transduction pathway. In a broader context, the outcome of this project is expected to advance our understanding of cell-cell interactions and intercellular communications, which are widespread and play essential roles in various biological systems and processes.