Characterizing the role of bacterial actin proteins, MamK and MamK-like, in the organization of magnetosome organelles in Magnetospirillum magneticum AMB-1.

摘要

Cellular organization is critical for life to flourish. Historically, this area of research has focused on eukaryotic systems, but recent advances have resulted in bacteria as model organisms to study cell biology. This research is aimed to elucidate how bacteria organize their internal structures. To address this question, the bacterial model organism, Magnetospirillum magneticum AMB-1 (AMB-1) was used and the role of two bacterial actin proteins, MamK and MamK-like, were studied.;The first chapter of this dissertation, a published review article (Cornejo-Warner et al., Current Opinion in Cell Biology 2014) written in collaboration with fellow Komeili lab member Elias Cornejo-Warner, introduces the topic of bacterial cell compartmentalization, highlighting examples from Bacillus subtilis and Caulobacter crescentus. Additionally, the organization of bacterial organelles is discussed with examples of two model systems, the magnetosomes of magnetotactic bacteria and the carboxysomes of cyanobacteria.;The second chapter of this dissertation, a combination of a published primary research article (Abreu et al., Journal of Bacteriology 2014) and unpublished supporting data, focuses on a bacterial actin protein, MamK-like. MamK-like is encoded in the magnetosome islet, a region of DNA distinct from the more heavily studied magnetosome island in AMB-1. The work described in this chapter, with assistance in molecular biology from Ertan Ozyamak and in vitro work from Soumaya Mannoubi, resulted in determining that this protein does indeed play a role in AMB-1 organelle alignment.;The third chapter of this dissertation (unpublished work) focuses on the efforts that were taken to further understand the mechanism of MamK turnover by Flourescence Recovery After Photobleaching (FRAP) studies, a continuation of previous work published by Olga Draper (Draper et al. Molecular Microbiology 2011).;The fourth chapter of this dissertation (unpublished work) focuses on the experiments developed (ex vivo: Bacterial two hybrid and in vitro : MamK affinity tagged pulldowns and Mass Spectrometry) to identify MamK and MamJ interacting proteins.;The fifth chapter of this dissertation is a conclusion of the work as it stands and proposals for future directions that could lead to a more comprehensive understanding of the organelle organization phenotype and bacterial actin behavior.