I. Petropoulos et al., Rat peptide methionine sulphoxide reductase: cloning of the cDNA, and down-regulation of gene expression and enzyme activity during aging, BIOCHEM J, 355, 2001, pp. 819-825
Peptide methionine sulphoxide reductase (PRMSR, EC 1.8,4,6), the msrA or pm
sR gene product, is a ubiquitous enzyme catalysing the reduction of methion
ine sulphoxide to methionine in proteins. Decreased expression and/or activ
ity of the PMSR with age could explain, at least in part, the accumulation
of oxidized protein observed upon aging. In test this hypothesis, the rat p
msR cDNA was cloned and sequenced. The recombinant protein was expressed, i
ts catalytic activity checked with a synthetic substrate and polyclonal ant
ibodies were raised against recombinant PMSR. The expression of the pmsR ge
ne and protein as well as its catalytic activity wire then analysed as a fu
nction of age in the rat brain and in two organs that express the most PMSR
, liver and kidney. It appears that pmsR gene expression decreases with age
in liver and kidney as early as 18 months, whereas protein level and prote
in activity are reduced in the three organs at the very end of the life of
the rat (26 months). These results suggest that the down-regulation of PMSR
can contribute to the accumulation of oxidized protein that has been assoc
iated with the aging process.