title: Functional roles of a predicted branched chain aminotransferase encoded by the LkBAT1 gene of the yeast Lachancea kluyveri.
abstract: Branched chain amino acid aminotransferases (BCATs) catalyze the last step of the biosynthesis and the first step of the catabolism of branched chain amino acids. In Saccharomyces cerevisiae, BCATs are encoded by the ScBAT1 and ScBAT2 paralogous genes. Analysis of Lachancea kluyveri genome sequence, allowed the identification of the LkBAT1 locus, which could presumably encode a BCAT. A second unlinked locus (LkBAT1bis), exhibiting sequence similarity to LkBAT1 was also identified. To determine the function of these putative BCATs, L. kluyveri mutant strains lacking LkBAT1, LkBAT1bis or both genes were generated and tested for VIL metabolism. LkBat1 displayed branched chain aminotransferase activity and is required for VIL biosynthesis and catabolism. However, Lkbat1Δ mutant is a valine and isoleucine auxotroph and a leucine bradytroph indicating that L. kluyveri harbors an alternative enzyme(s) involved in leucine biosynthesis. Additionally, heterologous reciprocal gene complementation between S. cerevisiae and L. kluyveri orthologous LkBAT1, ScBAT1 and ScBAT2 genes, confirmed that the mitochondrial LkBat1 functions as BCAT in S. cerevisiae, restoring wild type phenotype to the ScBAT1 null mutant. Conversely, LkBAT1bis did not display a role in BCAAs metabolism. However, when ethanol was used as carbon source, deletion of LkBAT1bis in an Lkbat1Δ null strain resulted in an extended 'lag' growth phase, pointing to a potential function of LkBAT1 and LkBAT1bis in the aerobic metabolism of L. kluyveri. These results confirm the BCAT function of LkBAT1 in L. kluyveri, and further support the proposition that the BCAT function in ancestral-type yeasts has been distributed in the two paralogous genes present in S. cerevisiae.
authors.affiliation: IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, no. 2055, Col. Lomas 4 Sección, San Luis Potosí, San Luis Potosí 78216, Mexico. Electronic address: javier.montalvo@ipicyt.edu.mx.
authors.forename: Javier
authors.initials: J
authors.lastname: Montalvo-Arredondo
authors.affiliation: IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, no. 2055, Col. Lomas 4 Sección, San Luis Potosí, San Luis Potosí 78216, Mexico. Electronic address: angel.jimenez@ipicyt.edu.mx.
authors.forename: Ángel
authors.initials: Á
authors.lastname: Jiménez-Benítez
authors.affiliation: Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, México D.F. 04510, Mexico. Electronic address: maritrini99@hotmail.com.
authors.forename: Maritrini
authors.initials: M
authors.lastname: Colón-González
authors.affiliation: Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, México D.F. 04510, Mexico. Electronic address: james_eua@hotmail.com.
authors.forename: James
authors.initials: J
authors.lastname: González-Flores
authors.affiliation: Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, México D.F. 04510, Mexico. Electronic address: mcflores@ifc.unam.mx.
authors.forename: Mirelle
authors.initials: M
authors.lastname: Flores-Villegas
authors.affiliation: Departamento de Bioquímica y Biología Estructural, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-242, México D.F. 04510, Mexico. Electronic address: amanjarr@ifc.unam.mx.
authors.forename: Alicia
authors.initials: A
authors.lastname: González
authors.affiliation: IPICYT, División de Biología Molecular, Instituto Potosino de Investigación Científica y Tecnológica, Camino a la Presa San José, no. 2055, Col. Lomas 4 Sección, San Luis Potosí, San Luis Potosí 78216, Mexico. Electronic address: lina@ipicyt.edu.mx.
authors.forename: Lina
authors.initials: L
authors.lastname: Riego-Ruiz
mesh_terms: D000597:Amino Acids, Branched-Chain / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D007532:Isoleucine / Q000235:genetics / Q000378:metabolism; D007930:Leucine / Q000235:genetics / Q000378:metabolism; D008928:Mitochondria / Q000378:metabolism; D004718:Saccharomycetales / Q000201:enzymology* / Q000235:genetics; D000637:Transaminases / Q000235:genetics / Q000378:metabolism*; D014633:Valine / Q000235:genetics / Q000378:metabolism
chemical_list: D000597:Amino Acids, Branched-Chain; D005656:Fungal Proteins; D007532:Isoleucine; D000637:Transaminases; C019798:branched-chain-amino-acid transaminase; D007930:Leucine; D014633:Valine
keywords: Aminotransferase; Branched chain amino acid metabolism; Fermentation; Lachancea kluyveri; Respiration; Saccharomyces cerevisiae