Do damaged proteins accumulate in Caenorhabditis elegans L-isoaspartate methyltransferase (pcm-1) deletion mutants?
The protein l-isoaspartate (d-aspartate) O-methyltransferase (E.C. 2. 1.1.77) can initiate the conversion of isomerized and racemized aspartyl residues to their normal l-aspartyl forms and has therefore been hypothesized to function as a repair enzyme, responsible for helping to limit the accumulation of damaged proteins in aging organisms. In this study, the effect of a disruption in the pcm-1 gene encoding the l-isoaspartyl methyltransferase was investigated in the nematode Caenorhabditis elegans. It was found that damaged proteins recognized by this enzyme accumulated to significant levels during long-term incubation of both pcm-1+ and pcm-1- nematodes in a specialized larval stage called the dauer. The l-isoaspartyl methyltransferase-deficient mutants accumulated about twice the level of damaged proteins as the control nematodes during dauer aging. The mutants also accumulated higher levels of damage when both strains were incubated at 30 degrees C for up to 3 days. However, when n
