Functional Enzymes that Repair Oxidized Methionine in Proteins from Leptospira interrogans

SASONI, N; GUERRERO, SA; IGLESIAS, AA; ARIAS, DG

Mar del Plata

Congreso; LI Reunión Anual de SAIB; 2015

SAIB

Methionine is an amino acid susceptible to be oxidized to methionine sulfoxide (MetSO). Reduction of MetSO to methionine is catalyzed by methionine sulfoxide reductase (MsR), an enzyme present in almost all organisms. Little information is available concerning of mechanisms for repairing oxidized proteins in Leptospira interrogans. Thesemechanisms would be relevant for the survival of this pathogen under oxidative conditions. Two genes encoding for putatives LinMsrA (linmsrA1 and linmsrA2) and one for LinMsrB (linmsrB) has been found in the L. interrogans genome project. In this work, we report the functional characterization of LinMsrB. The enzyme is a monomeric protein and specific for L-Met(R)SO reduction, using DTT or TNB as the reducing substrates. Interestingly, no MSR activity (in an in vitro assay) was observed using leptospira TRX as reducing substrate. In addition, we found that LinMsrB could compensate for MSR deficiency in yeast mutant strain lacking both MsrA and MsrB activities. The results support the occurrence of a metabolic pathway involved in the critical function of repairing oxidized macromolecules.