Mar1, a high mobility group box protein, regulates -alkane adsorption and cell morphology of the dimorphic yeast .

The dimorphic yeast possesses an excellent ability to utilize -alkane as a sole carbon and energy source. Although there are detailed studies on the enzymes that catalyze the reactions in the metabolic processes of -alkane in , the molecular mechanism underlying the incorporation of -alkane into the cells remains to be elucidated. Because adsorbs -alkane, we postulated that incorporates -alkane through direct interaction with it. We isolated and characterized mutants defective in adsorption to -hexadecane. One of the mutants harbored a nonsense mutation in (orphology and -alkane dsorption egulator 1) encoding a protein containing a high mobility group box. The deletion mutant of exhibited defects in adsorption to -hexadecane and filamentous growth on solid media, whereas the strain that overexpressed exhibited hyperfilamentous growth. Fluorescence microscopic observations suggested that Mar1 localizes in the nucleus. RNA-sequencing analysis revealed the alteration of the transcript levels of several genes, including those encoding transcription factors and cell surface proteins, by the deletion of . These findings suggest that is involved in the transcriptional regulation of the genes required for -alkane adsorption and cell morphology transition.IMPORTANCE, a dimorphic yeast capable of assimilating -alkane as a carbon and energy source, has been extensively studied as a promising host for bioconversion of -alkane into useful chemicals and bioremediation of soil and water contaminated by petroleum. While the metabolic pathway of -alkane in this yeast and the enzymes involved in this pathway have been well characterized, the molecular mechanism to incorporate -alkane into the cells is yet to be fully understood. Due to the ability of to adsorb -alkane, it has been hypothesized that incorporates -alkane through direct interaction with it. In this study, we identified a gene, , which plays a crucial role in the transcriptional regulation of the genes necessary for the adsorption to -alkane and the transition of the cell morphology in . Our findings provide valuable insights that could lead to advanced applications of in -alkane bioconversion and bioremediation.