Active nucleoprotein filaments of single-stranded binding protein and recA protein on single-stranded DNA have a regular repeating structure

Muniyappa, K. ; Williams, Kenneth ; Chase, John W. ; Radding, Charles M. (1990) Active nucleoprotein filaments of single-stranded binding protein and recA protein on single-stranded DNA have a regular repeating structure Nucleic Acids Research, 18 (13). pp. 3967-3973. ISSN 0305-1048

[img]
Preview
PDF - Publisher Version
1MB

Official URL: http://nar.oxfordjournals.org/content/18/13/3967.s...

Related URL: http://dx.doi.org/10.1093/nar/18.13.3967

Abstract

When E. coli single-stranded DNA binding protein (SSB) coats single-stranded DNA (ssDNA) in the presence of 1 mM MgCI2 it inhibits the subsequent binding of recA protein, whereas SSB binding to ssDNA in 12 mM MgCI2 promotes the binding of recA protein. These two conditions correspond respectively to those which produce 'smooth' and 'beaded' forms of ssDNA-SSB filaments. By gel filtration and immunoprecipitation we observed active nucleoprotein filaments of recA protein and SSB on ssDNA that contained on average 1 monomer of recA protein per 4 nucleotides and 1 monomer of SSB per 20-22 nucleotides. Filaments in such a mixture, when digested with micrococcal nuclease produced a regular repeating pattern, approximately every 70-80 nucleotides, that differed from the pattern observed when only recA protein was bound to the ssDNA. We conclude that the beaded ssDNA-SSB nucleoprotein filament readily binds recA protein and forms an intermediate that is active in the formation of joint molecules and can retain substantially all of the SSB that was originally bound.

Item Type:Article
Source:Copyright of this article belongs to Oxford University Press.
ID Code:22497
Deposited On:24 Nov 2010 08:29
Last Modified:17 May 2016 06:32

Repository Staff Only: item control page