Initial characterization of the functional cycle of YihA

Abstract

The worldwide shortage of new and effective antibiotics is becoming of increasing concern. New antibiotic targets are needed for testing and validation in the development of a new generation of antibiotics. This thesis investigates a potential antibiotic target, the essential GTPase YihA. The objective of this thesis was to gain a greater understanding of the mechanisms that regulate YihA’s functional cycle. Small angle X-ray scattering (SAXS) was used to obtain a low resolution solution structure of YihA and to provide information about the hydrodynamic characteristics of YihA including size, shape and flexibility. Further analysis of the SAXS data by disorder prediction programs and by modelling suggested that YihA in solution contains a folded core with flexible N-terminal and C-terminal tails. The SAXS structure of YihA, the SAXS-based modelling and the solution properties of YihA all supported dimerization of YihA in solution. Additionally, analytical gel filtration chromatography at concentrations of YihA closer to physiological concentrations revealed dimerization of YihA. The characteristics of the dimerization interface in the E. coli YihA crystal structure suggest that dimerization of YihA may play an important role in the functional cycle of YihA. Thus, these studies lay the groundwork for future structural and biochemical studies on the mechanism and significance of dimerization of YihA.