Mutations affecting components of C. elegans mitochondria have varied effects on the worm, from increased oxidative stress susceptibility to developmental defects. Perhaps the most interesting mutants are those that cause increased life span such as in the case of the
clk-1 gene, which is required for the biosynthesis of coenzyme Q (CoQ), an essential co-factor in mitochondrial respiration.. Here we introduce
mitr-1, a novel, nematode-specific gene, which plays an essential role in mitochondrial respiration and energy production and has many of the hall-marks of other clk genes, included an increased life span following gene knockout.
mitr-1(RNAi) worms are small, slow growing, have small brood sizes and display a slowdown in some rhythmic processes such as defecation and egg-laying, which manifests as a highly penetrant lethal egg-laying defect (Egl). Those worms that do not die from Egl have significantly extended life spans in a manner independent of the insulin-like/DAF-2 signalling pathway. MITR-1::GFP is localised to mitochondria throughout the worm and is expressed at all development stages. Biochemical analysis reveals that MITR-1 is required for mitochondrial respiration:
mitr-1(RNAi) worms have low oxygen consumption rates and low free-ATP levels. Removal of MITR-1 also results in expression of
hsp-6::GFP, which is a reporter of mitochondrial stress and protein instability.. In an attempt to better understand how MITR-1 contributes to mitochondrial respiration, we performed yeast two-hybrid screening to identify protein interactors of MITR-1. A putative physical interaction between MITR-1 and components of the E1 subunit of the pyruvate dehydrogenase complex (PDC) was identified. This implicates MITR-1 at the site of a critical metabolic reaction: the production of acetyl CoA from pyruvate. We are using GST-pull down experiments to test this interaction..