title: Sensitivity of Caenorhabditis elegans clk-1 mutants to ubiquinone side-chain length reveals multiple ubiquinone-dependent processes.
abstract: Ubiquinone (coenzyme Q, or Q) is a membrane constituent, whose head group is capable of accepting and donating electrons and whose lipidic side chain is composed of a variable number of isoprene subunits. A possible role for Q as a dietary antioxidant for treating conditions that involve altered cellular redox states is being intensely studied. Mutations in the clk-1 gene of the nematode Caenorhabditis elegans affect numerous physiological rates including behavioral rates, developmental rates, reproduction, and life span. clk-1 encodes a protein associated with the inner mitochondrial membrane that is necessary for Q biosynthesis in C. elegans. clk-1 mutants do not synthesize Q but accumulate demethoxyubiquinone, a Q synthesis intermediate that is able to partially sustain mitochondrial respiration in worms as well as in mammals. Recently, we and others have found that exogenous Q is necessary for the fertility and development of clk-1 mutants. Here, we take advantage of the clk-1 genetic model to identify structural features of Q that are functionally important in vivo. We show that clk-1 mutants are exquisitely sensitive to the length of the side chain of the Q they consume. We also identified differential sensitivity to Q side-chain length between null alleles of clk-1 (qm30 and qm51) and the weaker allele e2519. This allows us to propose a model where we distinguish several types of Q-dependent processes in vivo: processes that are very sensitive to Q side-chain length and processes that are permissive to Q with shorter chains.
authors.affiliation: Department of Biology, McGill University, Montreal, Québec H3A 1B1, Canada.
authors.forename: Abdelmadjid K
authors.initials: AK
authors.lastname: Hihi
authors.forename: Hania
authors.initials: H
authors.lastname: Kebir
authors.forename: Siegfried
authors.initials: S
authors.lastname: Hekimi
mesh_terms: D000483:Alleles; D000818:Animals; D015153:Blotting, Western; D017173:Caenorhabditis elegans / Q000235:genetics* / Q000502:physiology; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D009154:Mutation; D020033:Protein Isoforms; D014451:Ubiquinone / Q000378:metabolism*
chemical_list: C104339:CLK-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D020033:Protein Isoforms; D014451:Ubiquinone