Old yellow enzyme confers resistance of Hansenula polymorpha towards allyl alcohol.
In the methylotrophic yeast, Hansenula polymorpha, peroxisomes are formed during growth on methanol as sole carbon and energy source and contain the key enzymes for its metabolism, one of the major enzymes being alcohol oxidase (AO). Upon a shift of these cells to glucose-containing medium, peroxisomes become redundant for growth and are rapidly degraded via a highly selective process designated macropexophagy. H. polymorpha pdd mutants are disturbed in macropexophagy and hence retain high levels of peroxisomal AO activity upon induction of this process. To enable efficient isolation of PDD genes via functional complementation, we make use of the fact that AO can convert allyl alcohol into the highly toxic compound acrolein. When allyl alcohol is added to cells under conditions that induce macropexophagy, pdd mutants die, whereas complemented pdd mutants and wild-type cells survive. Besides isolating bona fide PDD genes, we occasionally obtained pdd transformants that retained high levels of AO activity although their allyl alcohol sensitive phenotype was suppressed. These invariably contained extra copies of a gene cluster encoding homologues of Saccharomyces carlsbergensis old yellow enzyme. Our data suggest that the proteins encoded by these genes detoxify acrolein by converting it into less harmful components.
Komduur
Janet A
JA
Eukaryotic Microbiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
Leão
Adriana N
AN
Monastyrska
Iryna
I
Veenhuis
Marten
M
Kiel
Jan A K W
JA
D000429:Alcohol Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D004352:Drug Resistance, Microbial; D000432:Methanol / Q000378:metabolism; D008969:Molecular Sequence Data; D020675:Peroxisomes / Q000378:metabolism; D010843:Pichia / Q000187:drug effects* / Q000201:enzymology; D020005:Propanols / Q000378:metabolism / Q000494:pharmacology*; D012641:Selection, Genetic; D017386:Sequence Homology, Amino Acid
D020005:Propanols; C006463:allyl alcohol; D000429:Alcohol Oxidoreductases; C019643:alcohol oxidase; D000432:Methanol