Functional analysis of Pseudomonas aeruginosa MutL D(Q/M)HA(X)2E(X)4E conserved motif
Correa, E. M. Eugenia; Martina, Mariana A. and Barra, José L.
CIQUIBIC-CONICET, Fac. de Ciencias Químicas, UNC
Córdoba, Argentina. E-mail: eecorrea@fcq.unc.edu.ar
The DNA mismatch repair system (MRS) corrects mismatched base pairs caused mainly by DNA replication errors, increasing the accuracy of DNA replication 20–400-fold. Currently, two types of MRS have been elucidated. In Escherichia coli and closely related bacteria MutH is the MRS endonuclease, while in the rest of bacteria and in eukaryotes, MutL homologues carry out this function.
A conserved D(Q/M)HA(X)2E(X)4E motif in the C-terminal region of MutL has been implicated in the metal-binding/endonuclease activity of these proteins. However, the contribution of individual amino acids to these activities remains unclear. In this work we characterized the sequence–function relationship of the DMHAAHERITYE motif of Pseudomonas aeruginosa MutL. We generated several point mutation derivatives and analyzed their in vivo functioning and in vitro endonuclease activity. Complementation analysis let us identify a new amino acid essential for the in vivo functioning of MutL protein. Unexpectedly, the in vitro analysis showed that mutation of some essential amino acids for the in vivo function does not affect the endonuclease activity of the full length protein.
Our results suggest that some conserved amino acids within the D(Q/M)HA(X)2E(X)4E motif could also be important for the interaction with the N-terminal region of MutL, with other proteins of the MRS, or be involved in regulatory functions.
Sección: Microbiología molecular
Modalidad de presentación: POSTER