title: Regulation of Nitrogen Metabolism by GATA Zinc Finger Transcription Factors inYarrowia lipolytica.
abstract: Fungi accumulate lipids in a manner dependent on the quantity and quality of the nitrogen source on which they are growing. In the oleaginous yeastYarrowia lipolytica, growth on a complex source of nitrogen enables rapid growth and limited accumulation of neutral lipids, while growth on a simple nitrogen source promotes lipid accumulation in large lipid droplets. Here we examined the roles of nitrogen catabolite repression and its regulation by GATA zinc finger transcription factors on lipid metabolism inY. lipolytica. Deletion of the GATA transcription factor genesgzf3andgzf2resulted in nitrogen source-specific growth defects and greater accumulation of lipids when the cells were growing on a simple nitrogen source. Deletion ofgzf1, which is most similar to activators of genes repressed by nitrogen catabolite repression in filamentous ascomycetes, did not affect growth on the nitrogen sources tested. We examined gene expression of wild-type and GATA transcription factor mutants on simple and complex nitrogen sources and found that expression of enzymes involved in malate metabolism, beta-oxidation, and ammonia utilization are strongly upregulated on a simple nitrogen source. Deletion ofgzf3results in overexpression of genes with GATAA sites in their promoters, suggesting that it acts as a repressor, whilegzf2is required for expression of ammonia utilization genes but does not grossly affect the transcription level of genes predicted to be controlled by nitrogen catabolite repression. Both GATA transcription factor mutants exhibit decreased expression of genes controlled by carbon catabolite repression via the repressormig1, including genes for beta-oxidation, highlighting the complex interplay between regulation of carbon, nitrogen, and lipid metabolism.IMPORTANCENitrogen source is commonly used to control lipid production in industrial fungi. Here we identified regulators of nitrogen catabolite repression in the oleaginous yeastY. lipolyticato determine how the nitrogen source regulates lipid metabolism. We show that disruption of both activators and repressors of nitrogen catabolite repression leads to increased lipid accumulation via activation of carbon catabolite repression through an as yet uncharacterized method.
authors.affiliation: Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington, USA.
authors.forename: Kyle R
authors.identifier: 0000-0003-2324-2881
authors.initials: KR
authors.lastname: Pomraning
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, USA.
authors.forename: Erin L
authors.identifier: 0000-0001-7827-8342
authors.initials: EL
authors.lastname: Bredeweg
authors.affiliation: Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland, Washington, USA.
authors.forename: Scott E
authors.identifier: 0000-0001-5085-3106
authors.initials: SE
authors.lastname: Baker
keywords: GATA; GATA transcription factor; Yarrowia lipolytica; biotechnology; carbon catabolite repression; carbon metabolism; gene regulation; lipid metabolism; lipid synthesis; metabolic regulation; nitrogen; nitrogen catabolite repression; nitrogen metabolism; oleaginous yeast; transcription factor; yeasts; zinc finger