We previously demonstrated that overexpression of the mismatch repair protein MutS in P. aeruginosa induces cell death and filamentation. These effects were not detected when overexpressed a C-terminal deletion MutS mutant. In addition, we found that the Cterminal domain copurified with the processivity factor Beta clamp (BC). The aim of this study is to determine if MutS interacts with BC and analyze the functional role of this interaction. First, we mutated the putative BC binding motif QSDLF located at the C-terminal domain of MutS generating the MutSB mutant. At difference of MutS, this mutant was not able to bind to BC in vitro. In concordance, overexpression of MutSB did not produce lethality and morphological changes. Since it has been proposed that BC could be involved in the repair of DNA replication errors, we analyzed the proficiency for mismatch repair activity in vivo of a mutant strain harboring the chromosomal mutSB mutant gene. This mutant strain presented a mutation frequency similar to the parental strain in the presence or absence of the mutagen 2-aminopurine. On the other hand, the analysis of growth kinetic indicated that the mutS strain showed a more extended lag period and a lower exponential oubling time compared to the parental strain. Thus, ours findings suggest that the MutS-BC interaction may be implicated in the regulation of cell cycle in P. Aeruginosa.