title: Candida tropicalis expresses two mitochondrial 2-enoyl thioester reductases that are able to form both homodimers and heterodimers.
abstract: Here we report on the cloning of a Candida tropicalis gene, ETR2, that is closely related to ETR1. Both genes encode enzymatically active 2-enoyl thioester reductases involved in mitochondrial synthesis of fatty acids (fatty acid synthesis type II) and respiratory competence. The 5'- and 3'-flanking (coding) regions of ETR2 and ETR1 are about 90% (97%) identical, indicating that the genes have evolved via gene duplication. The gene products differ in three amino acid residues: Ile67 (Val), Ala92 (Thr), and Lys251 (Arg) in Etr2p (Etr1p). Quantitative PCR analysis and reverse transcriptase-PCR indicated that both genes were expressed about equally in fermenting and ETR1 predominantly respiring yeast cells. Like the situation with ETR1, expression of ETR2 in respiration-deficient Saccharomyces cerevisiae mutant cells devoid of Ybr026p/Etr1p was able to restore growth on glycerol. Triclosan that is used as an antibacterial agent against fatty acid synthesis type II 2-enoyl thioester reductases inhibited growth of FabI overexpressing mutant yeast cells but was not able to inhibit respiratory growth of the ETR2- or ETR1-complemented mutant yeast cells. Resolving of crystal structures obtained via Etr2p and Etr1p co-crystallization indicated that all possible dimer variants occur in the same asymmetric unit, suggesting that similar dimer formation also takes place in vivo.
authors.affiliation: Biocenter Oulu, Department of Biochemistry, University of Oulu, Finland.
authors.forename: Juha M
authors.initials: JM
authors.lastname: Torkko
authors.forename: Kari T
authors.initials: KT
authors.lastname: Koivuranta
authors.forename: Alexander J
authors.initials: AJ
authors.lastname: Kastaniotis
authors.forename: Tomi T
authors.initials: TT
authors.lastname: Airenne
authors.forename: Tuomo
authors.initials: T
authors.lastname: Glumoff
authors.forename: Mika
authors.initials: M
authors.lastname: Ilves
authors.forename: Andreas
authors.initials: A
authors.lastname: Hartig
authors.forename: Aner
authors.initials: A
authors.lastname: Gurvitz
authors.forename: J Kalervo
authors.initials: JK
authors.lastname: Hiltunen
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D041022:Candida tropicalis / Q000201:enzymology*; D018360:Crystallography, X-Ray; D017931:DNA Primers / Q000737:chemistry; D019281:Dimerization; D050745:Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific); D005285:Fermentation; D005816:Genetic Complementation Test; D005947:Glucose / Q000378:metabolism; D013058:Mass Spectrometry; D008928:Mitochondria / Q000201:enzymology*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D019301:Oleic Acid / Q000378:metabolism; D044925:Oxidoreductases Acting on CH-CH Group Donors; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins
chemical_list: D017931:DNA Primers; D029701:Saccharomyces cerevisiae Proteins; D019301:Oleic Acid; D044925:Oxidoreductases Acting on CH-CH Group Donors; D050745:Enoyl-(Acyl-Carrier Protein) Reductase (NADPH, B-Specific); C541904:Etr1 protein, S cerevisiae; C434934:trans-2-enoyl-CoA reductase (NADPH); D009247:NADH, NADPH Oxidoreductases; D005947:Glucose