京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第18463号 / 医博第3918号 / 新制||医||1005(附属図書館) / 31341 / 京都大学大学院医学研究科医学専攻 / (主査)教授 岩井 一宏, 教授 生田 宏一, 教授 小川 誠司 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

<p>DNA replication is a fundamental process that must be precisely regulated to ensure timely and faithful transmission of genetic material for proliferation of all organisms. Replication initiation is regulated through a series of precisely timed protein–DNA and protein–protein interactions. In <em>Escherichia coli</em>, one regulatory mechanism of replication initiation occurs through SeqA binding to specific sequences within the <em>oriC</em>, resulting in origin sequestration. SeqA also plays a role in chromosome organization at the replication forks. Despite the functional importance of SeqA in <em>E. coli</em>, its DNA binding mechanism has remained elusive. The work described in this thesis has shown for the first time the minimal functional unit of SeqA that forms a high-affinity complex with DNA through the loss of symmetry. This is a novel observation that explains how SeqA can distinguish template versus newly replicated strand of DNA. We have also identified a protein–protein interaction surface that separates the roles of SeqA at the origin in sequestration and at the replication forks in chromosome organization. The final contribution of the thesis is in the exploration of SeqA functions in other bacterial species and demonstrating the structural and functional similarities between <em>Vibrio cholerae </em>SeqA and <em>E. coli </em>SeqA. Together our work has made a crucial connection between the structural organization of the protein and its functional ability to bind DNA.</p> / Doctor of Philosophy (PhD)