HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

J. Biol. Chem., Vol. 277, Issue 28, 24863-24869, July 12, 2002

This Article Full Text Full Text (PDF) All Versions of this Article: 277/28/24863    most recent M202041200v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Hedayati, M. A. Articles by Bryant, F. R. Search for Related Content PubMed PubMed Citation Articles by Hedayati, M. A. Articles by Bryant, F. R.

Effect of the Streptococcus pneumoniae MmsA Protein on the RecA Protein-promoted Three-strand Exchange Reaction
IMPLICATIONS FOR THE MECHANISM OF TRANSFORMATIONAL RECOMBINATION^*

Mohammad A. Hedayati, Scott E. Steffen, and Floyd R. Bryant

From the Department of Biochemistry and Molecular Biology, Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland 21205

Streptococcus pneumoniae is a naturally transformable bacterium that is able to incorporate DNA from its environment into its own chromosome. This process, known as transformational recombination, is dependent in part on the mmsA gene, which encodes a protein having a sequence that is 40% identical to that of the Escherichia coli RecG protein, a junction-specific DNA helicase believed to be involved in the branch migration of recombinational intermediates. We have developed an expression system for the MmsA protein and have purified the MmsA protein to more than 99% homogeneity. The MmsA protein has DNA-dependent ATP hydrolysis and DNA junction-helicase activities that are similar to those of the E. coli RecG protein. The effect of the MmsA protein on the S. pneumoniae RecA protein-promoted three-strand exchange reaction was also investigated. In the standard direction (circular single-stranded (ss) DNA + linear double-stranded (ds) DNA  linear ssDNA + nicked circular dsDNA), the MmsA protein appears to promote the branch migration of partially exchanged intermediates in a direction opposite of the RecA protein, resulting in a nearly complete inhibition of the overall strand exchange reaction. In the reverse direction (linear ssDNA + nicked circular dsDNA  circular ssDNA + linear dsDNA), however, the MmsA protein appears to facilitate the conversion of partially exchanged intermediates into fully exchanged products, leading to a pronounced stimulation of the overall reaction. These results are discussed in terms of the molecular mechanism of transformational recombination.

This article has been cited by other articles:

				D. E. Grove, S. Willcox, J. D. Griffith, and F. R. Bryant Differential Single-stranded DNA Binding Properties of the Paralogous SsbA and SsbB Proteins from Streptococcus pneumoniae J. Biol. Chem., March 25, 2005; 280(12): 11067 - 11073. [Abstract] [Full Text] [PDF]

				C. D. Pericone, S. Park, J. A. Imlay, and J. N. Weiser Factors Contributing to Hydrogen Peroxide Resistance in Streptococcus pneumoniae Include Pyruvate Oxidase (SpxB) and Avoidance of the Toxic Effects of the Fenton Reaction J. Bacteriol., December 1, 2003; 185(23): 6815 - 6825. [Abstract] [Full Text] [PDF]