Sensitivity of Caenorhabditis elegans clk-1 Mutants toUbiquinone Side-chain Length Reveals Multiple Ubiquinone-dependent Processes

Hihi, Abdelmadjid K.; Kébir, Hania; Hekimi, Siegfried

doi:10.1074/jbc.m305034200

Cited by 34 publications

(35 citation statements)

References 31 publications

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“…However, none of the CLK-1 protein detected in maternally rescued clk-1 mutants could be produced from the zygotic genome, as the qm30 mutation is a partial deletion of the gene that would result in a truncated protein, and as no CLK-1 protein at all is detected in clk-1(qm30) mutants (Fig. 3), as previously described (22). In conclusion, the presence of maternally derived wild-type CLK-1 protein in clk-1 maternally rescued animals likely accounts for the maternal rescue.…”

Section: Clk-1 Protein Is Present Throughout Larval Development In Masupporting

confidence: 64%

“…Protein samples were run on an acrylamide gel and transferred onto a nitrocellulose membrane (BioRad). The membrane was incubated with the primary anti-CLK-1 antibody 2774 (22) (1:1000), and subsequently with donkey anti-rabbit antibody (The Jackson Laboratory, 1:2500). The secondary antibody was detected by using the ECL kit (Amersham Biosciences).…”

Section: Methodsmentioning

confidence: 99%

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Molecular Mechanism of Maternal Rescue in the clk-1 Mutants of Caenorhabditis elegans

Burgess

Hihi

Bénard

et al. 2003

Journal of Biological Chemistry

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The clk-1 mutants of Caenorhabditis elegans display an average slowing down of physiological rates, including those of development, various behaviors, and aging. clk-1 encodes a hydroxylase involved in the biosynthesis of the redox-active lipid ubiquinone (co-enzyme Q), and in clk-1 mutants, ubiquinone is replaced by its biosynthetic precursor demethoxyubiquinone. Surprisingly, homozygous clk-1 mutants display a wild-type phenotype when issued from a heterozygous mother. Here, we show that this maternal effect is the result of the persistence of small amounts of maternally derived CLK-1 protein and that maternal CLK-1 is sufficient for the synthesis of considerable amounts of ubiquinone during development. However, gradual depletion of CLK-1 and ubiquinone, and expression of the mutant phenotype, can be produced experimentally by developmental arrest. We also show that the very long lifespan observed in daf-2 clk-1 double mutants is not abolished by the maternal effect. This suggests that, like developmental arrest, the increased lifespan conferred by daf-2 allows for depletion of maternal CLK-1, resulting in the expression of the synergism between clk-1 and daf-2. Thus, increased adult longevity can be uncoupled from the early mutant phenotypes, indicating that it is possible to obtain an increased adult lifespan from the late inactivation of processes required for normal development and reproduction.The clk-1 gene of Caenorhabditis elegans encodes a 187-amino acid protein that is orthologous to yeast Coq7p as well as to rodent and human sequences (1). CLK-1 is necessary for ubiquinone (coenzyme Q, or Q) 1 biosynthesis. Q n is a prenylated benzoquinone (the numerical subscript denotes the number of isoprene repeats, which is a species-specific trait) that is primarily involved in numerous redox reactions in the cell, including those in the mitochondrial electron transport chain. In its reduced form, Q is an antioxidant, preventing lipid peroxidation in biological membranes (2, 3). In the absence of CLK-1, worms and mice are defective in Q biosynthesis (4 -6) and accumulate the Q precursor, demethoxyubiquinone (DMQ 9 ) (5, 6). Yet, mitochondrial respiration is not strongly affected in clk-1 mutants, indicating that DMQ can substitute for some, but not all, of the Q functions in vivo (5-9).Despite the presence of DMQ, clk-1 mutants require Q from their bacterial food source to proceed through development and become fertile adults (4, 10). Indeed, when clk-1 mutants are transferred onto a Q 8 -deficient E. coli strain before the early larval stages, they arrest development at the second larval stage, and when the animals are transferred onto Q 8 -deficient bacteria later in development, they become sterile adults. This fact strongly suggests that DMQ 9 cannot functionally replace Q 9 for all of its cellular roles, and that at least some Q is required, which can be provided as Q 8 in the diet. Thus, the viability and overall good health of the clk-1 mutants seems to rely on a combination of endogenously produced DM...

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Section: Clk-1 Protein Is Present Throughout Larval Development In Masupporting

confidence: 64%

Section: Methodsmentioning

confidence: 99%

Molecular Mechanism of Maternal Rescue in the clk-1 Mutants of Caenorhabditis elegans

Burgess

Hihi

Bénard

et al. 2003

Journal of Biological Chemistry

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“…These animals were nearly sterile. This severe phenotype was recently independently verified (24). Even when fed the Q 7 diet as dauer larvae, their gonads displayed a strikingly abnormal phenotype, shrunken in size and disordered.…”

Section: Discussionmentioning

confidence: 77%

Reproductive Fitness and Quinone Content of Caenorhabditis elegans clk-1 Mutants Fed Coenzyme Q Isoforms of Varying Length

Jonassen

Davis

Larsen

et al. 2003

Journal of Biological Chemistry

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Caenorhabditis elegans clk-1 mutants lack coenzyme Q 9 and accumulate the biosynthetic intermediate demethoxy-Q 9 . A dietary source of ubiquinone (Q) is required for larval growth and development of the gonad and germ cells. We considered that uptake of the shorter Q 8 isoform present in the Escherichia coli food may contribute to the Clk phenotypes of slowed development and reduced brood size observed when the animals are fed Q-replete E. coli. To test the effect of isoprene tail length, N2 and clk-1 animals were fed E. coli engineered to produce Q 7 , Q 8 , Q 9 , or Q 10 . Wild-type nematodes showed no change in reproductive fitness regardless of the Q n isoform fed. clk-1(e2519) fed the Q 9 diet showed increased egg production; however, this diet did not improve reproductive fitness of the clk-1(qm30) animals. Furthermore, animals with the more severe clk-1(qm30) allele become sterile and their progeny inviable when fed Q 7 -containing bacteria. The content of Q 7 in the mitochondria of clk-1 animals was decreased relative to Q 8 , suggesting less effective transport of Q 7 to the mitochondria, impaired retention, or decreased stability. Additionally, regardless of E. coli diet, clk-1(qm30) animals contain a dysfunctional dense form of mitochondria. The gonads of clk-1(qm30) worms fed Q 7 -containing food were severely shrunken and disordered. The differential fertility of clk-1 mutant nematodes fed Q isoforms may result from changes in Q localization, altered recognition by Q-binding proteins, and/or potential defects in mitochondrial function resulting from the mutant CLK-1 polypeptide itself.

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“…C. elegans N2 strain showed both Q 9 and DMQ 9 , and also diet-derived Q 8 , and Q 8 -less fed N2 nematodes contained solely Q 9 in the plasma membrane. Surprisingly, Q 9 was detected in plasma membrane fractions isolated from both qm30 and qm51 clk-1 mutant nematodes along with Q 8 and DMQ 9 . Both Q 8 and Q 9 were reduced by NADH in these membranes but DMQ 9 was not significantly reduced.…”

Section: Introductionmentioning

confidence: 98%

“…Long-lived C. elegans clk-1 mutant strains accumulate demethoxy-coenzyme Q 9 (DMQ 9 ), an intermediate of Q 9 biosynthetic pathway [10,12]. DMQ 9 supports partially respiration in these mutants but cannot substitute all functions mediated by Q 9 in non-mitochondrial sites [8,13,14].…”

Section: Introductionmentioning

confidence: 99%

Coenzyme Q is irreplaceable by demethoxy‐coenzyme Q in plasma membrane ofCaenorhabditis elegans

et al. 2006

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A procedure was developed to isolate fractions enriched in plasma membrane from Caenorhabditis elegans. Coenzyme Q 9 (Q 9 ) was found in plasma membrane isolated from either wild-type or long-lived qm30 and qm51 clk-1 mutant strains of Caenorhabditis elegans, along with dietary coenzyme Q 8 (Q 8 ) and the biosynthetic intermediate demethoxy-Q 9 (DMQ 9 ). NADH was able to reduce both Q 8 and Q 9 , but not DMQ 9 . Our results indicate that DMQ 9 cannot achieve the same redox role of Q 9 in plasma membrane, suggesting that proportion of all these Q isoforms in plasma membrane must be an important factor in establishing the clk-1 mutant phenotype.

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Sensitivity of Caenorhabditis elegans clk-1 Mutants toUbiquinone Side-chain Length Reveals Multiple Ubiquinone-dependent Processes

Cited by 34 publications

References 31 publications

Molecular Mechanism of Maternal Rescue in the clk-1 Mutants of Caenorhabditis elegans

Molecular Mechanism of Maternal Rescue in the clk-1 Mutants of Caenorhabditis elegans

Reproductive Fitness and Quinone Content of Caenorhabditis elegans clk-1 Mutants Fed Coenzyme Q Isoforms of Varying Length

Coenzyme Q is irreplaceable by demethoxy‐coenzyme Q in plasma membrane ofCaenorhabditis elegans

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