Autoregulation of the Kluyveromyces lactis pyruvate decarboxylase gene KlPDC1 involves the regulatory gene RAG3

2015

PLoS ONE

The non-conventional yeast Yarrowia lipolytica possesses an ORF, YALI0E20207g, which encodes a protein with an amino acid sequence similar to hexokinases from different organisms. We have cloned that gene and determined several enzymatic properties of its encoded protein showing that it is an N-acetylglucosamine (NAGA) kinase. This conclusion was supported by the lack of growth in NAGA of a strain carrying a YALI0E20207g deletion. We named this gene YlNAG5. Expression of YlNAG5 as well as that of the genes encoding the enzymes of the NAGA catabolic pathway—identified by a BLAST search—was induced by this sugar. Deletion of YlNAG5 rendered that expression independent of the presence of NAGA in the medium and reintroduction of the gene restored the inducibility, indicating that YlNag5 participates in the transcriptional regulation of the NAGA assimilatory pathway genes. Expression of YlNAG5 was increased during sporulation and homozygous Ylnag5/Ylnag5 diploid strains sporulated very poorly as compared with a wild type isogenic control strain pointing to a participation of the protein in the process. Overexpression of YlNAG5 allowed growth in glucose of an Ylhxk1glk1 double mutant and produced, in a wild type background, aberrant morphologies in different media. Expression of the gene in a Saccharomyces cerevisiae hxk1 hxk2 glk1 triple mutant restored ability to grow in glucose.

Section: Discussionmentioning

confidence: 99%

The Gene YALI0E20207g from Yarrowia lipolytica Encodes an N-Acetylglucosamine Kinase Implicated in the Regulated Expression of the Genes from the N-Acetylglucosamine Assimilatory Pathway

Flores

2015

PLoS ONE

“…The activating protein could be Pdc2, a regulatory protein needed for high PDC1 expression (51). This model has received indirect support from results obtained with the respirofermentative yeast Kluyveromyces lactis (52). K. lactis has a single gene encoding Pdc,…”

Section: Pyruvate Decarboxylase Regulates the Transcription Of Its Enmentioning

confidence: 81%

“…1B) in which autoregulation is effected by an interaction between KlPdc1 and Rag3 that would sequester Rag3 in the cytoplasm. Abolition of this interaction will direct Rag3 to the nucleus, allowing increased transcription of KlPdc1 through direct or indirect action on the KlPDC1 promoter (52).…”

Section: Pyruvate Decarboxylase Regulates the Transcription Of Its Enmentioning

confidence: 99%

“…ScPdc1 may replace KlPdc1, and expression of an S. cerevisiae PDC1 gene bearing a point mutation that produces an inactive Pdc1 (54) caused a decrease in KlPdc1 transcription (53), suggesting a mechanism for autoregulation in K. lactis similar to that found in S. cerevisiae. Ottaviano et al (52), using a K. lactis strain with KlPDC1 deleted and harboring a KlPDC1-lacZ fusion gene, searched for mutants that abolished ␤-galactosidase production. One such mutant turned out to harbor a mutation in RAG3, a gene encoding a protein with important sequence similarity to the Pdc2 protein of S. cerevisiae (55).…”

Section: Pyruvate Decarboxylase Regulates the Transcription Of Its Enmentioning

confidence: 99%

See 1 more Smart Citation

The Expanding Landscape of Moonlighting Proteins in Yeasts

Flores

2016

Microbiol Mol Biol Rev

SUMMARYMoonlighting proteins are multifunctional proteins that participate in unrelated biological processes and that are not the result of gene fusion. A certain number of these proteins have been characterized in yeasts, and the easy genetic manipulation of these microorganisms has been useful for a thorough analysis of some cases of moonlighting. As the awareness of the moonlighting phenomenon has increased, a growing number of these proteins are being uncovered. In this review, we present a crop of newly identified moonlighting proteins from yeasts and discuss the experimental evidence that qualifies them to be classified as such. The variety of moonlighting functions encompassed by the proteins considered extends from control of transcription to DNA repair or binding to plasminogen. We also discuss several questions pertaining to the moonlighting condition in general. The cases presented show that yeasts are important organisms to be used as tools to understand different aspects of moonlighting proteins.

Unsaturated fatty acids-dependent linkage between respiration and fermentation revealed by deletion of hypoxic regulatoryKlMGA2gene in the facultative anaerobe-respiratory yeastKluyveromyces lactis

Ottaviano

Montanari

Angelis

et al. 2015

FEMS Yeast Research

In the yeast Kluyveromyces lactis, the inactivation of structural or regulatory glycolytic and fermentative genes generates obligate respiratory mutants which can be characterized by sensitivity to the mitochondrial drug antimycin A on glucose medium (Rag(-) phenotype). Rag(-) mutations can occasionally be generated by the inactivation of genes not evidently related to glycolysis or fermentation. One such gene is the hypoxic regulatory gene KlMGA2. In this work, we report a study of the many defects, in addition to the Rag(-) phenotype, generated by KlMGA2 deletion. We analyzed the fermentative and respiratory metabolism, mitochondrial functioning and morphology in the Klmga2Δ strain. We also examined alterations in the regulation of the expression of lipid biosynthetic genes, in particular fatty acids, ergosterol and cardiolipin, under hypoxic and cold stress and the phenotypic suppression by unsaturated fatty acids of the deleted strain. Results indicate that, despite the fact that the deleted mutant strain had a typical glycolytic/fermentative phenotype and KlMGA2 is a hypoxic regulatory gene, the deletion of this gene generated defects linked to mitochondrial functions suggesting new roles of this protein in the general regulation and cellular fitness of K. lactis. Supplementation of unsaturated fatty acids suppressed or modified these defects suggesting that KlMga2 modulates membrane functioning or membrane-associated functions, both cytoplasmic and mitochondrial.