Nucleotides and heteroduplex DNA preserve the active conformation of Pseudomonas aeruginosa MutS by inhibition of protein aggregation

PEZZA RJ; SMANIA AM; BARRA JL; ARGARAÑA, CE

PORTLAND PRESS LTD

Año: 2002 vol. 361 p. 87 - 87

utS, a component of the mismatch repair system begins the DNA reparation process by recognizing base}base mismatches or small insertion}deletion loops. We have cloned the mutS gene from the human opportunistic pathogen Pseudomonas aeruginosa and analysed the biochemical properties of the encoded protein. Complementation of the hypermutator phenotype of a P. aeruginosa mutS mutant strain indicated that the isolated gene was functional. When puri®ed MutS was incubated at 37 °C in the absence of ligands, a rapid inactivation of the oligonucleotide binding capability and ATPase activity occurred. However, the presence of ATP, ADP or heteroduplex oligonucleotides, but not homoduplex oligonucleotides, prevented the protein from being inactivated. The analysis of the protein by native PAGE indicated that the active conformation state correlates with the presence of MutS dimer. Analysis by gel-filltration chromatography showed that the inactive protein formed by incubation at 37 °C in the ab