Cyanobacterial Cell Division: Mechanisms and Inputs Towards the Decision to Divide

Michigan State University, East Lansing MI

Investigators

Abstract

Recently, recognition of the considerable promise of cyanobacteria as engineering platforms for bioindustrial and sustainable bioenergy solutions has fueled growing interest in research on these organisms. This research project aims to address the molecular regulation of cyanobacterial cell division. The project will use a combination of biochemical methods, advanced microscopy, and computational simulation to investigate core mechanisms of cell division in cyanobacteria. The project will investigate the influence that light has on this organism's cell division. As a related part of the project, a new molecular biology approach designed to allow experimental control of the abundance of target proteins in cyanobacteria will be developed, providing an additional tool to study the important proteins controlling division, but also permitting a potentially powerful new method for cyanobacterial research and engineering. The fundamental knowledge to be gained from this project will be broadly relevant to scientific questions of evolution and ecology, as well as to cyanobacterial engineering and applications in "green" bioenergy. The proposal will also provide training opportunities for two graduate students and numerous undergraduates from underrepresented groups through undergraduate research experiences. This project will employ the model unicellular rod-shaped cyanobacterium Synechococcus elongates, PCC7942, to investigate mechanistic and regulatory aspects of cell division in cyanobacteria. A combination of quantitative imaging, biochemical, molecular engineering, and modeling approaches will be used to understand how the unique cellular architecture and photosynthetic lifestyle of cyanobacteria impact their cell division systems in relation to those studied in classic heterotrophic models. Specifically, the S. elongatus homologs of the Min system proteins, which control the positioning of the cell division complex (divisome), will be investigated using localization studies involving careful construction of functional reporters expressed under endogenous and/or tunable promoters. The dynamics of the cyanobacterial Min proteins, their capacity to display oscillatory behavior, their genetic and biochemical interactions, and their influences on the organization of the divisome will be examined in relevant mutants and genetic backgrounds, and in the context of the large and potentially confounding thylakoid membrane system. The upstream influences of light, circadian rhythms, and photosynthetic metabolism on the control and activity of Min factors and cell division will also be investigated. To facilitate functional analysis of important/essential division proteins, a degron tag-based system will be developed to allow inducible degradation of target proteins. This technique may be broadly applicable to predictably regulating protein abundance beyond the scope of this project. Finally, the project will utilize computer simulations to examine the predicted effects of thylakoid membrane structure on the self-organization properties of the Min system and to compare modeling predictions to the experimentally derived results in S. elongatus.