High impact information on ABC1

• We have cloned and sequenced a novel yeast nuclear gene ABC1 which suppresses, in multicopy, the cytochrome b mRNA translation defect due to the nuclear mutation cbs2-223 [1].
• Analysis of the ABC1 gene shows that it is weakly expressed, it could code for a protein of 501 amino acids which has a typical presequence of a protein imported into mitochondria and which does not display a strong similarity to any known protein [1].
• The respiratory defect of C92 is complemented by COQ9 and suppressed by COQ8/ABC1 [2].
• A defect in coenzyme Q biosynthesis is responsible for the respiratory deficiency in Saccharomyces cerevisiae abc1 mutants [3].
• The findings presented here indicate that the previously reported thermosensitivity of the respiratory complexes of abc1/coq8 mutants results from the lack of Q and a general deficiency in respiration, rather than a specific phenotype due to dysfunction of the Abc1 polypeptide [3].

Biological context of ABC1

• In this work we show that a segment of yeast genomic DNA containing ABC1/COQ8 and neighboring genes suppresses the respiratory and Q-deficient phenotypes of the coq6 mutant, coq6-1 [4].
• The nuclear ABC1 gene is essential for the correct conformation and functioning of the cytochrome bc1 complex and the neighbouring complexes II and IV in the mitochondrial respiratory chain [5].

Associations of ABC1 with chemical compounds

• ABC1 was subsequently identified as COQ8 and found to be necessary for yeast coenzyme Q synthesis [4].
• Studies presented here indicate that abc1/coq8 null mutants are defective in Q biosynthesis and accumulate 3-hexaprenyl-4-hydroxybenzoic acid as the predominant intermediate [3].

Regulatory relationships of ABC1

• Based on this identification, Abc1p was postulated to activate the bc1 complex and function as a chaperone of cytochrome b [4].

Other interactions of ABC1

• The Saccharomyces cerevisiae gene ABC1 was originally isolated as a multicopy suppressor of a yeast strain harboring a mutation in a cytochrome b translational activator (cbs2-223) [4].
• Suppression by COQ8/ABC1 of C92, but not other coq9 mutants tested, has been related to an increase in the mitochondrial concentration of several enzymes of the pathway [2].

References