SSB에 의한 단사DNA의 2차구조의 불안정화 = Destabilization of Secondary Structures in Single-Stranded DNA by SSB

다국어 초록 (Multilingual Abstract)

SBS has been well-characterized as a helix-destabilizing activity and as a DNA binding protein which binds single strands specifically and cooperatively. This protein plays and important role in may aspects of DNA metabolism including replication, recombination, and repair. Its exact role in these processes is unknown, although the ability to bind cooperatively to single-stranded DNA may be necessary feature. In vitro. SSB stimulates recA protein-mediate DNA strand exchange. SSB is suggested to act by removing DNA secondary structures which is inaccessible to recA protein binding, and is then displaced by the recA protein. This transient helix-destabilizing role for SSB has recently been called into question by the demonstration that SSB exists in multiple binding modes which are influenced by ionic strength. The binding mode present at low ionic strength is highly cooperative. The binding mode at higher concentrations of Mg++ exhibits a much lower cooperativity in DNA binding. The secondary structure destabilization for SSB actions in the recA system implicitly assume that SSB can bind to and denature regions of secondary structures in ssDNA. A specific technique was used to determine if SSB has this capability under conditions optimal for recA reaction.
The method employs the specific cleavage of regions of secondary structure in ssDNA by restriction endonuclease. Results of restriction endonuclease protection by SSB and titration experiments suggest that SSB is exclude from regions of secondary structures present in native ssDNA. Both SSB and recA protein are required for the elimination of the secondary structure under conditions with higher concentration of Mg++.

목차 (Table of Contents)

• 서론
• 재료 및 방법
• 1. SSB protein 분리
• 2. M13mp8 ssDNA 2차구조의 절단반응
• 결과 및 고찰