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Abstract

Acinetobacter baylyi are highly competent Gram-negative bacteria that are easy to culture in vitro, making them model organisms for studying natural transformation. Natural transformation is a means of genetic exchange for bacteria that occurs by the uptake and incorporation of extracellular DNA into a bacterium's own genome to enhance fitness and survival. It is hypothesized that hair-like appendages known as type IV pili (T4P) or homologous structures make up the competence machine that facilitates natural transformation, and these appendages are also associated with the bacterial form of movement known as twitching motility. While studies have investigated the role of pilin proteins and general competence proteins in the competence machine, little is known about how the cytoskeleton influences its assembly and function. The cytoskeleton includes shape-determining proteins that specify cell shape and maintain intracellular organization. These proteins might influence natural transformation and twitching motility in A. baylyi because the assembly, extension, and retraction of T4P requires localization of the necessary components, which is facilitated in part by the cytoskeleton. Specifically, I tested the importance of two shape genes, mreC and rodA, on transformation and twitching motility by comparing knockout mutants to wild type A. baylyi cells. The results indicate that RodA plays an important role in natural transformation and twitching motility, as deletion of rodA decreased both processes. The mreC knockout did not have a significant impact on transformation or twitching motility. The data suggests that cellular organization facilitated by shape-determining proteins like RodA impacts the proper assembly and function of the competence and locomotive machine.

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