title: Bifunctional aldehyde/alcohol dehydrogenase (ADHE) in chlorophyte algal mitochondria.
abstract: Protein profiles of mitochondria isolated from the heterotrophic chlorophyte Polytomella sp. grown on ethanol at pH 6.0 and pH 3.7 were analyzed by Blue Native and denaturing polyacrylamide gel electrophoresis. Steady-state levels of oxidative phosphorylation complexes were influenced by external pH. Levels of an abundant, soluble, mitochondrial protein of 85 kDa and its corresponding mRNA increased at pH 6.0 relative to pH 3.7. N-terminal and internal sequencing of the 85 kDa mitochondrial protein together with the corresponding cDNA identified it as a bifunctional aldehyde/alcohol dehydrogenase (ADHE) with strong similarity to homologues from eubacteria and amitochondriate protists. A mitochondrial targeting sequence of 27 amino acids precedes the N-terminus of the mature mitochondrial protein. A gene encoding an ADHE homologue was also identified in the genome of Chlamydomonas reinhardtii, a photosynthetic relative of Polytomella. ADHE reveals a complex picture of sequence similarity among homologues. The lack of ADHE from archaebacteria indicates a eubacterial origin for the eukaryotic enzyme. Among eukaryotes, ADHE has hitherto been characteristic of anaerobes since it is essential to cytosolic energy metabolism of amitochondriate protists such as Giardia intestinalis and Entamoeba histolytica. Its abundance and expression pattern suggest an important role for ADHE in mitochondrial metabolism of Polytomella under the conditions studied. The current data are compatible with the view that Polytomella ADHE could be involved either in ethanol production or assimilation, or both, depending upon environmental conditions. Presence of ADHE in an oxygen-respiring algal mitochondrion and co-expression at ambient oxygen levels with respiratory chain components is unexpected with respect to the view that eukaryotes acquired ADHE genes specifically as an adaptation to an anaerobic lifestyle.
authors.affiliation: Departamento de Genética Molecular, Instituto de Fisiología Celular, Universidad Nacional Autáonoma de México, México D.F. 04510, México. Ariane.Atteia@uni-duesseldorf.de
authors.forename: Ariane
authors.initials: A
authors.lastname: Atteia
authors.forename: Robert
authors.initials: R
authors.lastname: van Lis
authors.forename: Guillermo
authors.initials: G
authors.lastname: Mendoza-Hernández
authors.forename: Katrin
authors.initials: K
authors.lastname: Henze
authors.forename: William
authors.initials: W
authors.lastname: Martin
authors.forename: Hector
authors.initials: H
authors.lastname: Riveros-Rosas
authors.forename: Diego
authors.initials: D
authors.lastname: González-Halphen
mesh_terms: D000426:Alcohol Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D000444:Aldehyde Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D015152:Blotting, Northern; D000460:Chlorophyta / Q000201:enzymology / Q000235:genetics*; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D015180:Electrophoresis, Gel, Two-Dimensional; D015971:Gene Expression Regulation, Enzymologic; D006863:Hydrogen-Ion Concentration; D008928:Mitochondria / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010085:Oxidative Phosphorylation; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012995:Solubility
chemical_list: D018076:DNA, Complementary; D024101:Mitochondrial Proteins; D009097:Multienzyme Complexes; D000426:Alcohol Dehydrogenase; D000444:Aldehyde Dehydrogenase