Mar1, an HMG-box protein, regulatesn-alkane adsorption and cell morphology of the dimorphic yeastYarrowia lipolytica

Abstract

The dimorphic yeastYarrowia lipolyticapossesses an excellent ability to utilizen-alkane as a sole carbon and energy source. Although there are detailed studies on the enzymes that catalyze the reactions in the metabolic processes ofn-alkane inY. lipolytica, the molecular mechanism underlying the incorporation ofn-alkane into the cells remains to be elucidated. BecauseY. lipolyticaadsorbsn-alkane, we postulated thatY. lipolyticaincorporatesn-alkane through direct interaction with it. We isolated and characterized mutants defective in adsorption ton-hexadecane. One of the mutants harbored a nonsense mutation inMAR1(Morphology andn-alkane Adsorption Regulator) encoding a protein containing a high mobility group box. The deletion mutant ofMAR1exhibited defects in adsorption ton-hexadecane and filamentous growth on solid media, whereas the strain that overexpressedMAR1exhibited hyperfilamentous growth. Fluorescence microscopic observations suggested that Mar1 localizes in the nucleus. RNA-seq analysis revealed the alteration of the transcript levels of several genes, including those encoding transcription factors and cell surface proteins, by the deletion ofMAR1. These findings suggest thatMAR1is involved in the transcriptional regulation of the genes required forn-alkane adsorption and cell morphology transition.