Epigenetic Regulation and the E. Coli Cell Cycle

University Of Pennsylvania, Philadelphia PA

Investigators

Abstract

This project will explore the relationship between the bacterial cell cycle and DNA methylation-dependent, heritable gene regulation in the bacterium Escherichia coli. The model system will be the outer membrane protein Ag43, which is under heritable but reversible control, also called phase variation. Previous work from the principal investigator's laboratory has shown that the heritable nature of Ag43 regulation is a direct result of inheritance of the DNA methylation state at its regulatory region, and thus can be defined as epigenetic regulation. The limited number of regulatory factors involved and the ability to genetically manipulate the system make this an excellent model system. This project addresses how the DNA methylation state is maintained during DNA replication, which results in synthesis of unmethylated DNA and disrupts protein-nucleo complexes. The Specific Aims of this proposal are to identify how DNA-protein interactions at hemi-methylated DNA contribute to the inheritance of the DNA methylation state, and to determine whether passage of the DNA replication fork is required for a switch from the unmethylated to methylated state. Protein-DNA interactions will be analyzed in vitro and phase variation examined in mutant isolates. Ag43 expression can enhance biofilm formation, and understanding the behavior of these communities of bacteria is of significance for microbial ecology, pathogenesis and biotechnology. This project therefore may contribute to the development of novel antimicrobial strategies and identification of new drug targets. By providing new insight into the complex networks that coordinate cellular events, this project may also benefit studies in eukaryotic cells in which epigenetic regulation is an important factor for cell development. This project provides excellent training opportunities at all levels of expertise. Undergraduate projects can be developed, but the theoretical and technical complexities will also challenge postdoctoral fellows.