The C-terminal region of Escherichia coli MutS and protein oligomerization

MIGUEL V; PEZZA RJ; ARGARAÑA CE

BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2007 vol. 360 p. 412 - 417

0006-291X

Escherichia coli MutS, an 853 amino acids oligomeric protein, is involved in the postreplicative DNA mismatch repair and avoidance of homeologous recombination. By constructing MutS  mutated versions of the C-terminal region, we determined that deletion of the last 7 C-terminal amino acids is enough to abolish tetramer formation and that the K850A substitution destabilize the tetramer structure. It is proposed that the C-terminal extreme alpha helix (residues 839-850) of the protein may play an important role in protein oligomerization. We also show that the C-terminal region or the C-terminal plus the HTH domain of MutS, fused to the monomeric Maltose Binding Protein promote oligomerization of the chimeric protein. However, chemical cross-linking experiments indicate that the HTH domain improves the oligomerization properties of the fused protein. Escherichia coli cells expressing the fused proteins become hypermutator suggesting that the C-terminal region of MutS plays an important role in vivo.