I. NMR study on the interactions of the SeqA protein with hemimethylated and fully methylated DNA = SeqA와 hemimethylated, fully methylated DNA의 상호작용에 관한 NMR 연구.

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I. NMR study on the interactions of the SeqA protein with hemimethylated and fully methylated DNA Replication of Escherichia coli chromosomal DNA initiates at a unique site, oriC, and occurs precisely once per cell cycle. Methylation of oriC by Dam methylase, which methylates N6 of adenine in the GATC sequences, enables SeqA to negatively regulate both primary and secondary replication initiation. SeqA delays the primary replication initiation at fully methylated oriC until a cell reaches its critical mass, counteracting the DnaA protein that activates replication initiation. After replication is initiated, SeqA specifically binds the hemimethylated GATC sites, as the daughter strands are transiently unmethylated, and sequesters oriC from Dam methylase and DnaA, thus preventing secondary replication initiation within a single cell cycle. In the absence of SeqA, E. coli cells are viable, but initiation of DNA replication is asynchronous and occurs several times during each cell cycle. In the present study, our object is to examine the dynamics of SeqA with binding of DNAs. The DNAs used in this study contain the hemimethylated and fully methylated GATC sequence. The flexibility of a protein has been suggested as an important factor in a protein-ligand or a protein-nucleic acid interaction. In the crystal structure of the SeqA (51-181 amino acids) with the hemimethylated DNA, it was known that the hemimethylated $^mA:T$ pair of the DNA associates with the L3 loop of SeqA. Although the crystal structure of the SeqA C-terminal segment (51-181 amino acids) has been determined in a complex with hemimethylated DNA, it is meaningful to examine the dynamics of SeqA with DNA in order to understand the precise protein-DNA interaction. To identify the possibility of the progress of this object, we confirmed the $^1H-^{15}N$ HSQC spectrum of SeqA alone with well dispersed pattern and carried out the chemical shift perturbation experiment. II. NMR study of the inter...
Choi, Byong-Seokresearcher최병석researcher
한국과학기술원 : 화학과,
Issue Date
297303/325007  / 020063478

학위논문(석사) - 한국과학기술원 : 화학과, 2008.2, [ v, 59 p. ]


SeqA; E.coli; oriC; hemimethylated GATC site; 대장균; DNA 복제; SeqA; E.coli; oriC; hemimethylated GATC site; 대장균; DNA 복제

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