Beyond cell shape: A novel role for the bacterial actin MreB in chemotaxis

Oklahoma State University Stillwater, Stillwater OK

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Abstract

Project Summary/Abstract The cytoskeleton is important for proper physiology in both eukaryotic and bacterial cells. However, unlike eukaryotic cells, for which much work has been done to determine the role of the cytoskeleton in cellular physiology, there has been very little work on this aspect of bacterial cell biology. Disruption of the cytoskeleton often leads to cell shape changes and cell death. The major actin homolog in bacteria is MreB and it is thought to be essential for rod shape. The goal of this work is to remove this black box of microbiology and determine the role of the cytoskeleton in microbial physiology. A deeper understanding of MreB’s function and bacterial physiology can guide the development of novel antibacterial therapies, as well as provide insight into the evolution of the cytoskeleton. Disrupting basic physiology will make it difficult for infections to take hold in the body, giving the host’s natural defenses time to clear the infection. This proposal will focus on the role of MreB in cell shape regulation, growth, and chemotaxis. To understand how MreB functions we will take a systematic approach MreB using a combination of genetic, biophysical, and microscopy techniques to building and analyzing an alanine-scanning mutagenesis library of MreB mutants that have replaced the native allele. We will analyze the effect of these mutations on multiple aspects of cell shape and look for suppressor mutations to loss of cell shape. We will screen this library for the effects on chemotaxis to determine domains of MreB that interact with the chemotaxis machinery. All together this research will determine the role of the bacterial cytoskeleton in bacterial chemotaxis, cell shape, and growth. These insights will provide a starting point for the development of novel therapeutics that can be used to stop or slow infections, giving the host immune system time to clear the infection. Additionally, many pathogens use flagella-based motility to increase their virulence. Learning more about how chemotaxis works will enable us to develop therapies that can inhibit motility in the host, lessening infection. To the best of our knowledge, this study will be the first to take a systematic approach to understanding MreB biology.