title: Cloning and characterization of KlCOX18, a gene required for activity of cytochrome oxidase in Kluyveromyces lactis.
abstract: We describe the isolation and initial characterization of KlCOX18, a gene that is essential for the assembly of a functional cytochrome oxidase in the yeast Kluyveromyces lactis. Cells carrying a recessive nuclear mutation in this gene are respiratory deficient and contain reduced levels of cytochromes a and a3. The KlCOX18 gene has been cloned by complementation of the respective nuclear mutation, sequenced, and disrupted. KlCOX18 is located on chromosome II and contains an open reading frame of 939 base pairs. The corresponding protein exhibits 70.4% similarity to the Cox18p of Saccharomyces cerevisiae. It contains three possible membrane-spanning domains and a putative amino-terminal mitochondrial import sequence. The strain carrying a null mutation in KlCOX18 does not grow on non-fermentable carbon sources and is deficient in both cytochrome c oxidase and respiratory activity. It is proposed that KlCox18p, like its S. cerevisiae counterpart, provides an important function at a later step of the cytochrome oxidase assembly pathway.
authors.affiliation: Department of Microbiology and Virology, Comenius University, Mlynská dolina B2, 842 15 Bratislava, Slovak Republic.
authors.forename: I
authors.initials: I
authors.lastname: Hikkel
authors.forename: Y
authors.initials: Y
authors.lastname: Gbelská
authors.forename: Q J
authors.initials: QJ
authors.lastname: van der Aart
authors.forename: G
authors.initials: G
authors.lastname: Lubecu
authors.forename: J
authors.initials: J
authors.lastname: Subík
mesh_terms: D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D015825:Chromosomes, Fungal; D003001:Cloning, Molecular; D003433:Crosses, Genetic; D003576:Electron Transport Complex IV / Q000378:metabolism*; D005656:Fungal Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D005800:Genes, Fungal; D005808:Genes, Recessive; D005816:Genetic Complementation Test; D005838:Genotype; D007716:Kluyveromyces / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: C109359:COX18 protein, Kluyveromyces lactis; D005656:Fungal Proteins; D003576:Electron Transport Complex IV