Dataset Information

Connection between the Rag4 glucose sensor and the KlRgt1 repressor in Kluyveromyces lactis.

ABSTRACT: The RAG4 gene encodes for the sole transmembrane glucose sensor of Kluyveromyces lactis. A rag4 mutation leads to a fermentation-deficient phenotype (Rag- phenotype) and to a severe defect in the expression of the major glucose transporter gene RAG1. A recessive extragenic suppressor of the rag4 mutation has been identified. It encodes a protein (KlRgt1) 31% identical to the Saccharomyces cerevisiae Rgt1 regulator of the HXT genes (ScRgt1). The Klrgt1 null mutant displays abnormally high levels of RAG1 expression in the absence of glucose but still presents an induction of RAG1 expression in the presence of glucose. KlRgt1 is therefore only a repressor of RAG1. As described for ScRgt1, the KlRgt1 repressor function is controlled by phosphorylation in response to high glucose concentration and this phosphorylation is dependent on the sensor Rag4 and the casein kinase Rag8. However, contrary to that observed with ScRgt1, KlRgt1 is always bound to the RAG1 promoter. This article reveals that the key components of the glucose-signaling pathway are conserved between S. cerevisiae and K. lactis, but points out major differences in Rgt1 regulation and function that might reflect different carbon metabolism of these yeasts.

SUBMITTER: Rolland S

PROVIDER: S-EPMC1602099 | biostudies-literature | 2006 Oct

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Connection between the Rag4 glucose sensor and the KlRgt1 repressor in Kluyveromyces lactis.

Rolland Stéphane S Hnatova Martina M Lemaire Marc M Leal-Sanchez Juana J Wésolowski-Louvel Micheline M

Genetics 20060618 2

The RAG4 gene encodes for the sole transmembrane glucose sensor of Kluyveromyces lactis. A rag4 mutation leads to a fermentation-deficient phenotype (Rag- phenotype) and to a severe defect in the expression of the major glucose transporter gene RAG1. A recessive extragenic suppressor of the rag4 mutation has been identified. It encodes a protein (KlRgt1) 31% identical to the Saccharomyces cerevisiae Rgt1 regulator of the HXT genes (ScRgt1). The Klrgt1 null mutant displays abnormally high levels ...[more]

PMID: 16783006

Similar Datasets

Project description:The analysis of glucose signaling in the Crabtree-positive eukaryotic model organism Saccharomyces cerevisiae has disclosed a dual role of its hexokinase ScHxk2, which acts as a glycolytic enzyme and key signal transducer adapting central metabolism to glucose availability. In order to identify evolutionarily conserved characteristics of hexokinase structure and function, the cellular response of the Crabtree-negative yeast Kluyveromyces lactis to rag5 null mutation and concomitant deficiency of its unique hexokinase KlHxk1 was analyzed by means of difference gel electrophoresis. In total, 2,851 fluorescent spots containing different protein species were detected in the master gel representing all of the K. lactis proteins that were solubilized from glucose-grown KlHxk1 wild-type and mutant cells. Mass spectrometric peptide analysis identified 45 individual hexokinase-dependent proteins related to carbohydrate, short-chain fatty acid and tricarboxylic acid metabolism as well as to amino acid and protein turnover, but also to general stress response and chromatin remodeling, which occurred as a consequence of KlHxk1 deficiency at a minimum 3-fold enhanced or reduced level in the mutant proteome. In addition, three proteins exhibiting homology to 2-methylcitrate cycle enzymes of S. cerevisiae were detected at increased concentrations, suggesting a stimulation of pyruvate formation from amino acids and/or fatty acids. Experimental validation of the difference gel electrophoresis approach by post-lysis dimethyl labeling largely confirmed the abundance changes detected in the mutant proteome via the former method. Taking into consideration the high proportion of identified hexokinase-dependent proteins exhibiting increased proteomic levels, KlHxk1 is likely to have a repressive function in a multitude of metabolic pathways. The proteomic alterations detected in the mutant classify KlHxk1 as a multifunctional enzyme and support the view of evolutionary conservation of dual-role hexokinases even in organisms that are less specialized than S. cerevisiae in terms of glucose utilization.

Project description:BACKGROUND: Even before having its genome sequence published in 2004, Kluyveromyces lactis had long been considered a model organism for studies in genetics and physiology. Research on Kluyveromyces lactis is quite advanced and this yeast species is one of the few with which it is possible to perform formal genetic analysis. Nevertheless, until now, no complete metabolic functional annotation has been performed to the proteins encoded in the Kluyveromyces lactis genome. RESULTS: In this work, a new metabolic genome-wide functional re-annotation of the proteins encoded in the Kluyveromyces lactis genome was performed, resulting in the annotation of 1759 genes with metabolic functions, and the development of a methodology supported by merlin (software developed in-house). The new annotation includes novelties, such as the assignment of transporter superfamily numbers to genes identified as transporter proteins. Thus, the genes annotated with metabolic functions could be exclusively enzymatic (1410 genes), transporter proteins encoding genes (301 genes) or have both metabolic activities (48 genes). The new annotation produced by this work largely surpassed the Kluyveromyces lactis currently available annotations. A comparison with KEGG's annotation revealed a match with 844 (~90%) of the genes annotated by KEGG, while adding 850 new gene annotations. Moreover, there are 32 genes with annotations different from KEGG. CONCLUSIONS: The methodology developed throughout this work can be used to re-annotate any yeast or, with a little tweak of the reference organism, the proteins encoded in any sequenced genome. The new annotation provided by this study offers basic knowledge which might be useful for the scientific community working on this model yeast, because new functions have been identified for the so-called metabolic genes. Furthermore, it served as the basis for the reconstruction of a compartmentalized, genome-scale metabolic model of Kluyveromyces lactis, which is currently being finished.

Project description:The transcription factor KlPdr1p, belonging to the Zn2Cys6 family, is a central regulator of efflux pump expression in Kluyveromyces lactis. To better understand how KlPDR1-mediated drug resistance is achieved in K. lactis, we used DNA microarrays to identify genes whose expression was affected by deletion or overexpression of the KlPDR1 gene. All microarray experiments were performed using the 30K Kluyveromyces lactis NRRL Y-1140 microarray (MYcroarray, 5692 Plymouth Road, Ann Arbor, MI 48105, USA). Exponentially growing (1 x 107 cells ml-1) K. lactis PM6-7A cells (wild-type, PM6-7A/pdr1∆ and the wild-type transformed with multicopy plasmid carrying the gain-of-function allele of KlPDR1* gene) (Balazfyova et al. 2013), were collected and total RNA was isolated using RNeasy midi kit (Qiagen GmbH, Germany). 1 mg of total RNA was linearly amplified and labelled using Amino allyl MessageAmpII aRNA Amplification kit (Ambion, USA) with two different fluorescent dyes; AlexaFluor647 and AlexaFluor555 (Life Technologies, Germany). 4 µg of labelled RNA was hybridized (18 h at 45°C) in 6x SSPE with addition of formamide (10%), tween-20 (0,01%) and microarray-specofoc control oligos (1%, MYcroarray, USA). After washing, microarray images and two-color GPR output files were obtained using the microarray scanner InnoScan 900 and Mapix software version 7.3.1 (Inopsys, France). The two-color GPR files were processed using the R version 3.0.2 (R Core Team (2014). R: A language and enviroment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. URL http://www.R-project.org) and functions available in the limma package (Smyth 2005). Briefly, the two-color GPR files were omported using the read.maimages() function, background-substracted using the “minimum“ method and within-array-normalized using the “loess“ method. The between-array normalisation was achieved using the “Aquantile“ method. For further analysis, only genes with log2FC ˃2 were selected and confirmed using qPCR.

Dataset Information

Connection between the Rag4 glucose sensor and the KlRgt1 repressor in Kluyveromyces lactis.

Publications

Connection between the Rag4 glucose sensor and the KlRgt1 repressor in Kluyveromyces lactis.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure