DNA Replication of Bacteriophage T7

  • 첨부된 파일이 없습니다.
  • Hit 167
  • Writer 이태화
  • 2014-01-22


[분자.생명과학부/생물공학연구소 공동세미나]


▶제목 : DNA Replication of Bacteriophage T7

▶연사 : Seung-Joo Lee [Harvard Medical School]

▶일시 : 2007년 6월 20일(수) 오후4시

▶장소 : 생명과학과 1층세미나실 104호



Simple and efficient organization of T7 bacteriophage replisome provides an excellent model system for DNA replication study.  Its four components (DNA polymerase, primase and helicase, single-stranded DNA binding protein and E. coli thioredoxin) are sufficient to perform coordinated synthesis of both leading and lagging DNA strands at replication fork.  At the center of the replisome, 63kD-protein encoded by T7 gene 4 exhibits two essential activities of both primase and helicase.  Located at the N-terminal is the primase domain that recognizes specific DNA sequence from which it synthesizes oligoribonucleotides to initiates lagging strand synthesis.  Several charged amino acid residues at the catalytic site are involved in ATP binding affinity and further Mg2+-mediated catalysis.  A flexible linker connecting Zn motif and catalytic site of the primase also participates in primer synthesis by modulating synthesis modes.  Both Zn motif and catalytic subdomain are required for recognition of the specific sequence, which is significantly enhanced by binding of cognate NTPs.  The C-terminal of helicase domain in the gene 4 protein forms hexamer and unwinds duplex DNA at the expense of dTTP hydrolysis to generate single-stranded DNA template for DNA polymerase.  Among residues composed of dNTP binding site at the interface of subunit, some residues are responsible for the unique utilization of dTTP.  Within the inside of hexameric structure, basic residues contribute to DNA binding through either direct contact or subunit interaction.  Besides it individual activities, T7 gene 4 protein play a coordinating role by engaging in interactions with other proteins in the replisome.  One of those interactions occurs at the acidic C-terminal region of helicase domain where thioredoxin-binding loop of DNA polymerase makes stable binding for leading strand synthesis.  Such extensive communications between components in T7 replisome regulate activity of each protein and ultimately control overall efficiency of DNA replication.


※문의 : 생명과학과/박상기교수 (☎279-2349)