Function and regulation of an aldehyde dehydrogenase essential for ethanol and methanol metabolism of the yeast,Komagataella phaffii

Abstract

AbstractThe genome of the methylotrophic yeast,Komagataella phaffiiharbours multiple genes encoding putative alcohol dehydrogenases and aldehyde dehydrogenases (ALDs). Here, we demonstrate that one of the ALDs denoted as ALD-A is essential for ethanol metabolism. A zinc finger transcription factor known as Mxr1p regulatesALD-Atranscription by binding to Mxr1p response elements (MXREs) in theALD-Apromoter. Mutations which abrogate Mxr1p binding toALD-AMXREsin vitroabolish transcriptional activation fromALD-Apromoterin vivo. Mxr1p regulatesALD-Aexpression during ethanol as well as methanol metabolism. ALD-A is essential for the utilization of methanol andΔald-ais deficient in alcohol oxidase (AOX), a key enzyme of methanol metabolism. AOX protein but not mRNA levels are down regulated inΔald-a.ALD-A and AOX localize to cytosol and peroxisomes respectively during methanol metabolism suggesting that they are unlikely interact with each otherin vivo. This study has led to the identification of Mxr1p as a key regulator ofALD-Atranscription during ethanol and methanol metabolism ofK. phaffii. Post-transcriptional regulation of AOX protein levels by ALD-A during methanol metabolism is another unique feature of this study.