RecA Protein of Mycobacterium tuberculosis Possesses pH-Dependent Homologous DNA Pairing and Strand Exchange Activities: Implications for Allele Exchange in Mycobacteria


Autoria(s): Vaze, Moreshwar B; Muniyappa, K
Data(s)

09/03/1999

Resumo

To gain insights into inefficient allele exchange in mycobacteria, we compared homologous pairing and strand exchange reactions promoted by RecA protein of Mycobacterium tuberculosis to those of Escherichia coli RecA protein. The extent of single-stranded binding protein (SSB)-stimulated formation of joint molecules by MtRecA was similar to that of EcRecA over a wide range of pH values. In contrast, strand exchange promoted by MtRecA was inhibited around neutral pH due to the formation of DNA networks. At higher pH, MtRecA was able to overcome this constraint and, consequently, displayed optimal strand exchange activity. Order of addition experiments suggested that SSB, when added after MtRecA, was vital for strand exchange. Significantly, with shorter duplex DNA, MtRecA promoted efficient strand exchange without network formation in a pH-independent fashion. Increase in the length of duplex DNA led to incomplete strand exchange with concomitant rise in the formation of intermediates and networks in a pH-dependent manner. Treatment of purified networks with S1 nuclease liberated linear duplex DNA and products, consistent with a model in which the networks are formed by the invasion of hybrid DNA by the displaced linear single-stranded DNA. Titration of strand exchange reactions with ATP or salt distinguished a condition under which the formation of networks was blocked, but strand exchange was not significantly affected. We discuss how these results relate to inefficient allele exchange in mycobacteria.

Formato

application/pdf

Identificador

http://eprints.iisc.ernet.in/25667/1/bi9819125.pdf

Vaze, Moreshwar B and Muniyappa, K (1999) RecA Protein of Mycobacterium tuberculosis Possesses pH-Dependent Homologous DNA Pairing and Strand Exchange Activities: Implications for Allele Exchange in Mycobacteria. In: Biochemistry, 38 (10). pp. 3175-3186.

Publicador

American Chemical Society

Relação

http://pubs.acs.org/doi/full/10.1021/bi9819125

http://eprints.iisc.ernet.in/25667/

Palavras-Chave #Biochemistry
Tipo

Journal Article

PeerReviewed