Multicellular development depends on cell-cell signaling and the consequences of this dialogue between cells, which are often large-scale changes in gene expression. Hence, a fundamental goal of developmental biologists is to determine how cell-cell signals orchestrate global changes in gene transcription. The multicellular nature of the Myxococcus xanthus developmental cycle makes it an excellent model system for studying this basic problem in developmental biology. During M. xanthus development, large groups of cells migrate to focal points and begin constructing a multicellular structure called a fruiting body. Once the fruiting body is molded into its final form, cells inside this structure differentiate into dormant, stress-resistant spores. Many M. xanthus genes are developmentally regulated, and cell-cell signaling is required for the temporal expression of these genes. However, what happens between production of these cell-cell signals and transcription of developmental genes has remained relatively uncharted territory. This project focuses on a family of proteins that play a prominent role in regulating these coordinated changes in gene expression, the NtrC family of transcriptional activators. It has been proposed that M. xanthus uses a series of NtrC-like proteins to activate expression of specific sets of genes at specific times in development; seven different NtrC-like activators that are required for development have been uncovered. Using genetic and biochemical approaches, this research project will examine the role that NtrC-like activators play in orchestrating developmental gene expression in M. xanthus.
