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

The genome of the methylotrophic yeast, harbours 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 regulates transcription by binding to Mxr1p response elements (MXREs) in the promoter. Mutations which abrogate Mxr1p binding to MXREs abolish transcriptional activation from promoter . Mxr1p regulates expression during ethanol as well as methanol metabolism. ALD-A is essential for the utilization of methanol and is deficient in alcohol oxidase (AOX), a key enzyme of methanol metabolism. AOX protein but not mRNA levels are down regulated in ALD-A and AOX localize to cytosol and peroxisomes respectively during methanol metabolism suggesting that they are unlikely interact with each other . This study has led to the identification of Mxr1p as a key regulator of transcription during ethanol and methanol metabolism of . Post-transcriptional regulation of AOX protein levels by ALD-A during methanol metabolism is another unique feature of this study.