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Wang L, Wang A, Wang D, Hong J. The novel properties of Kluyveromyces marxianus glucose sensor/receptor repressor pathway and the construction of glucose repression-released strains. Microb Cell Fact 2023; 22:123. [PMID: 37430283 DOI: 10.1186/s12934-023-02138-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Accepted: 06/27/2023] [Indexed: 07/12/2023] Open
Abstract
BACKGROUND Glucose repression in yeast leads to the sequential or diauxic utilization of mixed sugars and reduces the co-utilization of glucose and xylose from lignocellulosic biomasses. Study of the glucose sensing pathway helps to construct glucose repression-released yeast strains and enhance the utilization of lignocellulosic biomasses. RESULTS Herein, the glucose sensor/receptor repressor (SRR) pathway of Kluyveromyces marxianus which mainly consisted of KmSnf3, KmGrr1, KmMth1, and KmRgt1 was studied. The disruption of KmSNF3 led to a release of glucose repression, enhanced xylose consumption and did not result in deficient glucose utilization. Over-expression of glucose transporter gene restored the mild decrease of glucose utilization ability of Kmsnf3 strain to a similar level of the wildtype strain but did not restore glucose repression. Therefore, the repression on glucose transporter is parallel to glucose repression to xylose and other alternative carbon utilization. KmGRR1 disruption also released glucose repression and kept glucose utilization ability, although its xylose utilization ability was very weak with xylose as sole carbon source. The stable mutant of KmMth1-ΔT enabled the release of glucose repression irrespective that the genetic background was Kmsnf3, Kmmth1, or wildtype. Disruption of KmSNF1 in the Kmsnf3 strain or KmMTH1-ΔT overexpression in Kmsnf1 strain kept constitutive glucose repression, indicating that KmSNF1 was necessary to release the glucose repression in both SRR and Mig1-Hxk2 pathway. Finally, overexpression of KmMTH1-ΔT released the glucose repression to xylose utilization in S. cerevisiae. CONCLUSION The glucose repression-released K. marxianus strains constructed via a modified glucose SRR pathway did not lead to a deficiency in the utilization ability of sugar. The obtained thermotolerant, glucose repression-released, and xylose utilization-enhanced strains are good platforms for the construction of efficient lignocellulosic biomass utilization yeast strains.
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Affiliation(s)
- Lingya Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Anran Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China
| | - Dongmei Wang
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230027, China.
| | - Jiong Hong
- School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, 230027, P. R. China.
- Hefei National Laboratory for Physical Science at the Microscale, Hefei, Anhui, 230026, P. R. China.
- Biomedical Sciences and Health Laboratory of Anhui Province, University of Science and Technology of China, Hefei, 230027, China.
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2
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Nowrouzi B, Lungang L, Rios-Solis L. Exploring optimal Taxol® CYP725A4 activity in Saccharomyces cerevisiae. Microb Cell Fact 2022; 21:197. [PMID: 36123694 PMCID: PMC9484169 DOI: 10.1186/s12934-022-01922-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Accepted: 09/12/2022] [Indexed: 11/23/2022] Open
Abstract
Background CYP725A4 catalyses the conversion of the first Taxol® precursor, taxadiene, to taxadiene-5α-ol (T5α-ol) and a range of other mono- and di-hydroxylated side products (oxygenated taxanes). Initially known to undergo a radical rebound mechanism, the recent studies have revealed that an intermediate epoxide mediates the formation of the main characterised products of the enzyme, being T5α-ol, 5(12)-oxa-3(11)-cyclotaxane (OCT) and its isomer, 5(11)-oxa-3(11)-cyclotaxane (iso-OCT) as well as taxadienediols. Besides the high side product: main product ratio and the low main product titre, CYP725A4 is also known for its slow enzymatic activity, massively hindering further progress in heterologous production of Taxol® precursors. Therefore, this study aimed to systematically explore the key parameters for improving the regioselectivity and activity of eukaryotic CYP725A4 enzyme in a whole-cell eukaryotic biocatalyst, Saccharomyces cerevisiae. Results Investigating the impact of CYP725A4 and reductase gene dosages along with construction of self-sufficient proteins with strong prokaryotic reductases showed that a potential uncoupling event accelerates the formation of oxygenated taxane products of this enzyme, particularly the side products OCT and iso-OCT. Due to the harmful effect of uncoupling products and the reactive metabolites on the enzyme, the impact of flavins and irons, existing as prosthetic groups in CYP725A4 and reductase, were examined in both their precursor and ready forms, and to investigate the changes in product distribution. We observed that the flavin adenine dinucleotide improved the diterpenoids titres and biomass accumulation. Hemin was found to decrease the titre of iso-OCT and T5α-ol, without impacting the side product OCT, suggesting the latter being the major product of CYP725A4. The interaction between this iron and the iron precursor, δ-Aminolevulinic acid, seemed to improve the production of these diterpenoids, further denoting that iso-OCT and T5α-ol were the later products. While no direct correlation between cellular-level oxidative stress and oxygenated taxanes was observed, investigating the impact of salt and antioxidant on CYP725A4 further showed the significant drop in OCT titre, highlighting the possibility of enzymatic-level uncoupling event and reactivity as the major mechanism behind the enzyme activity. To characterise the product spectrum and production capacity of CYP725A4 in the absence of cell growth, resting cell assays with optimal neutral pH revealed an array of novel diterpenoids along with higher quantities of characterised diterpenoids and independence of the oxygenated product spectra from the acidity effect. Besides reporting on the full product ranges of CYP725A4 in yeast for the first time, the highest total taxanes of around 361.4 ± 52.4 mg/L including 38.1 ± 8.4 mg/L of T5α-ol was produced herein at a small, 10-mL scale by resting cell assay, where the formation of some novel diterpenoids relied on the prior existence of other diterpenes/diterpenoids as shown by statistical analyses. Conclusions This study shows how rational strain engineering combined with an efficient design of experiment approach systematically uncovered the promoting effect of uncoupling for optimising the formation of the early oxygenated taxane precursors of Taxol®. The provided strategies can effectively accelerate the design of more efficient Taxol®-producing yeast strains. Supplementary Information The online version contains supplementary material available at 10.1186/s12934-022-01922-1.
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Affiliation(s)
- Behnaz Nowrouzi
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, EH9 3BF, UK.,Centre for Synthetic and Systems Biology (SynthSys), The University of Edinburgh, Edinburgh, EH9 3BD, UK
| | - Liang Lungang
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, EH9 3BF, UK.,Centre for Synthetic and Systems Biology (SynthSys), The University of Edinburgh, Edinburgh, EH9 3BD, UK
| | - Leonardo Rios-Solis
- Institute for Bioengineering, School of Engineering, The University of Edinburgh, Edinburgh, EH9 3BF, UK. .,Centre for Synthetic and Systems Biology (SynthSys), The University of Edinburgh, Edinburgh, EH9 3BD, UK. .,School of Natural and Environmental Sciences, Newcastle University, Newcastle upon Tyne, NE1 7RU, UK.
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3
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Pacheco A, Donzella L, Hernandez-Lopez MJ, Almeida MJ, Prieto JA, Randez-Gil F, Morrissey JP, Sousa MJ. Hexose transport in Torulaspora delbrueckii: identification of Igt1, a new dual-affinity transporter. FEMS Yeast Res 2021; 20:5715911. [PMID: 31981362 DOI: 10.1093/femsyr/foaa004] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2019] [Accepted: 01/24/2020] [Indexed: 01/23/2023] Open
Abstract
Torulaspora delbrueckii is a yeast species receiving increasing attention from the biotechnology industry, with particular relevance in the wine, beer and baking sectors. However, little is known about its sugar transporters and sugar transport capacity, frequently a rate-limiting step of sugar metabolism and efficient fermentation. Actually, only one glucose transporter, Lgt1, has been characterized so far. Here we report the identification and characterization of a second glucose transporter gene, IGT1, located in a cluster, upstream of LGT1 and downstream of two other putative hexose transporters. Functional characterization of IGT1 in a Saccharomyces cerevisiae hxt-null strain revealed that it encodes a transporter able to mediate uptake of glucose, fructose and mannose and established that its affinity, as measured by Km, could be modulated by glucose concentration in the medium. In fact, IGT1-transformed S. cerevisiae hxt-null cells, grown in 0.1% glucose displayed biphasic glucose uptake kinetics with an intermediate- (Km = 6.5 ± 2.0 mM) and a high-affinity (Km = 0.10 ± 0.01 mM) component, whereas cells grown in 2% glucose displayed monophasic kinetics with an intermediate-affinity (Km of 11.5 ± 1.5 mM). This work contributes to a better characterization of glucose transport in T. delbrueckii, with relevant implications for its exploitation in the food industry.
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Affiliation(s)
- Andreia Pacheco
- Centre of Environmental and Molecular Biology, Department of Biology, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal
| | - Lorena Donzella
- Centre of Environmental and Molecular Biology, Department of Biology, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal
- School of Microbiology, Centre for Synthetic Biology and Biotechnology, Environmental Research Institute, APC Microbiome Institute, University College Cork, T12YT20 Cork, Ireland
| | - Maria Jose Hernandez-Lopez
- Department of Biotechnology, Instituto de Agroqumica y Tecnologia de los Alimentos, Consejo Superior de Investigaciones Cientficas, Avda. Agustn Escardino, 7. 46980-Paterna, Valencia, Spain
| | - Maria Judite Almeida
- Centre of Environmental and Molecular Biology, Department of Biology, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal
| | - Jose Antonio Prieto
- Department of Biotechnology, Instituto de Agroqumica y Tecnologia de los Alimentos, Consejo Superior de Investigaciones Cientficas, Avda. Agustn Escardino, 7. 46980-Paterna, Valencia, Spain
| | - Francisca Randez-Gil
- Department of Biotechnology, Instituto de Agroqumica y Tecnologia de los Alimentos, Consejo Superior de Investigaciones Cientficas, Avda. Agustn Escardino, 7. 46980-Paterna, Valencia, Spain
| | - John P Morrissey
- School of Microbiology, Centre for Synthetic Biology and Biotechnology, Environmental Research Institute, APC Microbiome Institute, University College Cork, T12YT20 Cork, Ireland
| | - Maria João Sousa
- Centre of Environmental and Molecular Biology, Department of Biology, University of Minho, Campus of Gualtar, 4710-057 Braga, Portugal
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Improvement of Torulaspora delbrueckii Genome Annotation: Towards the Exploitation of Genomic Features of a Biotechnologically Relevant Yeast. J Fungi (Basel) 2021; 7:jof7040287. [PMID: 33920164 PMCID: PMC8070057 DOI: 10.3390/jof7040287] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 04/02/2021] [Accepted: 04/08/2021] [Indexed: 12/15/2022] Open
Abstract
Saccharomyces cerevisiae is the most commonly used yeast in wine, beer, and bread fermentations. However, Torulaspora delbrueckii has attracted interest in recent years due to its properties, ranging from its ability to produce flavor- and aroma-enhanced wine to its ability to survive longer in frozen dough. In this work, publicly available genomes of T. delbrueckii were explored and their annotation was improved. A total of 32 proteins were additionally annotated for the first time in the type strain CBS1146, in comparison with the previous annotation available. In addition, the annotation of the remaining three T. delbrueckii strains was performed for the first time. eggNOG-mapper was used to perform the functional annotation of the deduced T. delbrueckii coding genes, offering insights into its biological significance, and revealing 24 clusters of orthologous groups (COGs), which were gathered in three main functional categories: information storage and processing (28% of the proteins), cellular processing and signaling (27%), and metabolism (23%). Small intraspecies variability was found when considering the functional annotation of the four available T. delbrueckii genomes. A comparative study was also conducted between the T. delbrueckii genome and those from 386 fungal species, revealing a high number of homologous genes with species from the Zygotorulaspora and Zygosaccharomyces genera, but also with Lachancea and S. cerevisiae. Lastly, the phylogenetic placement of T. delbrueckii was clarified using the core homologs that were found across 204 common protein sequences of 386 fungal species and strains.
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Özkan E, Kartal B, Yılmazer M, Palabıyık B. Iron regulates hexose transporters in Schizosaccharomyces pombe. J Basic Microbiol 2019; 59:458-464. [PMID: 30730059 DOI: 10.1002/jobm.201800618] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 12/28/2018] [Accepted: 01/16/2019] [Indexed: 11/09/2022]
Abstract
This study focuses on the effect of iron on hexose transporters which perform glucose uptake. For this aim, we investigated the role of iron in glucose utilization and expression of hexose transporters in Schizosaccharomyces pombe. We applied different iron concentrations (1, 2, 5, 10 mM) to the cells grown up to mid-logarithmic phase. According to analysis of cell viability and morphology, we determined 2 mM and 5 mM as non-toxic and toxic doses, respectively. Besides, glucose consumption efficiency increased (1.5-fold) in the cells which were exposed to these iron concentrations. qRT-PCR analysis of hexose transporter genes showed that the expression of ght2 and ght8 genes were downregulated under both non-toxic and toxic iron conditions, but that of ght5 gene was significantly decreased only by toxic iron dose. In conclusion, it was suggested for the first time in this study that the Ght5 protein, as being high affinity hexose transporter, might play a role in sensing and signaling of iron stress.
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Affiliation(s)
- Egemen Özkan
- Department of Molecular Biology and Genetics, Institute of Graduate Studies in Sciences, Istanbul University, Istanbul, Turkey
| | - Burcu Kartal
- Department of Molecular Biology and Genetics, Institute of Graduate Studies in Sciences, Istanbul University, Istanbul, Turkey
| | - Merve Yılmazer
- Faculty of Science, Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey
| | - Bedia Palabıyık
- Faculty of Science, Department of Molecular Biology and Genetics, Istanbul University, Istanbul, Turkey
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Welkenhuysen N, Borgqvist J, Backman M, Bendrioua L, Goksör M, Adiels CB, Cvijovic M, Hohmann S. Single-cell study links metabolism with nutrient signaling and reveals sources of variability. BMC SYSTEMS BIOLOGY 2017; 11:59. [PMID: 28583118 PMCID: PMC5460408 DOI: 10.1186/s12918-017-0435-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Accepted: 05/24/2017] [Indexed: 01/02/2023]
Abstract
BACKGROUND The yeast AMPK/SNF1 pathway is best known for its role in glucose de/repression. When glucose becomes limited, the Snf1 kinase is activated and phosphorylates the transcriptional repressor Mig1, which is then exported from the nucleus. The exact mechanism how the Snf1-Mig1 pathway is regulated is not entirely elucidated. RESULTS Glucose uptake through the low affinity transporter Hxt1 results in nuclear accumulation of Mig1 in response to all glucose concentrations upshift, however with increasing glucose concentration the nuclear localization of Mig1 is more intense. Strains expressing Hxt7 display a constant response to all glucose concentration upshifts. We show that differences in amount of hexose transporter molecules in the cell could cause cell-to-cell variability in the Mig1-Snf1 system. We further apply mathematical modelling to our data, both general deterministic and a nonlinear mixed effect model. Our model suggests a presently unrecognized regulatory step of the Snf1-Mig1 pathway at the level of Mig1 dephosphorylation. Model predictions point to parameters involved in the transport of Mig1 in and out of the nucleus as a majorsource of cell to cell variability. CONCLUSIONS With this modelling approach we have been able to suggest steps that contribute to the cell-to-cell variability. Our data indicate a close link between the glucose uptake rate, which determines the glycolytic rate, and the activity of the Snf1/Mig1 system. This study hence establishes a close relation between metabolism and signalling.
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Affiliation(s)
- Niek Welkenhuysen
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96, Gothenburg, Sweden
| | - Johannes Borgqvist
- Department of Mathematical Sciences, Chalmers University of Technology and the University of Gothenburg, SE-412 96, Gothenburg, Sweden
| | - Mattias Backman
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96, Gothenburg, Sweden
| | - Loubna Bendrioua
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96, Gothenburg, Sweden
| | - Mattias Goksör
- Department of Physics, University of Gothenburg, SE-412 96, Gothenburg, Sweden
| | - Caroline B Adiels
- Department of Physics, University of Gothenburg, SE-412 96, Gothenburg, Sweden
| | - Marija Cvijovic
- Department of Mathematical Sciences, Chalmers University of Technology and the University of Gothenburg, SE-412 96, Gothenburg, Sweden.
| | - Stefan Hohmann
- Department of Chemistry and Molecular Biology, University of Gothenburg, SE-412 96, Gothenburg, Sweden. .,Department of Biology and Biological Engineering, Chalmers University of Technology, SE-412 96, Gothenburg, Sweden.
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7
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Choi E, Kim J, Kim S, Seo S, Lane S, Park Y, Jin Y, Seo J. Enhanced production of 2,3‐butanediol in pyruvate decarboxylase‐deficient
Saccharomyces cerevisiae
through optimizing ratio of glucose/galactose. Biotechnol J 2016; 11:1424-1432. [DOI: 10.1002/biot.201600042] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Revised: 08/06/2016] [Accepted: 08/08/2016] [Indexed: 01/04/2023]
Affiliation(s)
- Eun‐Ji Choi
- Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University Seoul Republic of Korea
| | - Jin‐Woo Kim
- Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University Seoul Republic of Korea
| | - Soo‐Jung Kim
- Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University Seoul Republic of Korea
| | - Seung‐Oh Seo
- Department of Food Science and Human Nutrition, and Institute for Genomic Biology, University of Illinois at Urbana‐Champaign Urbana Illinois USA
| | - Stephan Lane
- Department of Food Science and Human Nutrition, and Institute for Genomic Biology, University of Illinois at Urbana‐Champaign Urbana Illinois USA
| | - Yong‐Cheol Park
- Department of Advanced Fermentation Fusion Science and Technology, Kookmin University Seoul Republic of Korea
| | - Yong‐Su Jin
- Department of Food Science and Human Nutrition, and Institute for Genomic Biology, University of Illinois at Urbana‐Champaign Urbana Illinois USA
| | - Jin‐Ho Seo
- Department of Agricultural Biotechnology and Center for Food and Bioconvergence, Seoul National University Seoul Republic of Korea
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8
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Improvement of lactic acid production in Saccharomyces cerevisiae by a deletion of ssb1. J Ind Microbiol Biotechnol 2015; 43:87-96. [PMID: 26660479 DOI: 10.1007/s10295-015-1713-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2015] [Accepted: 11/23/2015] [Indexed: 10/22/2022]
Abstract
Polylactic acid (PLA) is an important renewable polymer, but current processes for producing its precursor, lactic acid, suffer from process inefficiencies related to the use of bacterial hosts. Therefore, improving the capacity of Saccharomyces cerevisiae to produce lactic acid is a promising approach to improve industrial production of lactic acid. As one such improvement required, the lactic acid tolerance of yeast must be significantly increased. To enable improved tolerance, we employed an RNAi-mediated genome-wide expression knockdown approach as a means to rapidly identify potential genetic targets. In this approach, several gene knockdown targets were identified which confer increased acid tolerance to S. cerevisiae BY4741, of which knockdown of the ribosome-associated chaperone SSB1 conferred the highest increase (52%). This target was then transferred into a lactic acid-overproducing strain of S. cerevisiae CEN.PK in the form of a knockout and the resulting strain demonstrated up to 33% increased cell growth, 58% increased glucose consumption, and 60% increased L-lactic acid production. As SSB1 contains a close functional homolog SSB2 in yeast, this result was counterintuitive and may point to as-yet-undefined functional differences between SSB1 and SSB2 related to lactic acid production. The final strain produced over 50 g/L of lactic acid in under 60 h of fermentation.
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9
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Reznicek O, Facey S, de Waal P, Teunissen A, de Bont J, Nijland J, Driessen A, Hauer B. Improved xylose uptake in Saccharomyces cerevisiae
due to directed evolution of galactose permease Gal2 for sugar co-consumption. J Appl Microbiol 2015; 119:99-111. [DOI: 10.1111/jam.12825] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 04/01/2015] [Accepted: 04/08/2015] [Indexed: 12/19/2022]
Affiliation(s)
- O. Reznicek
- Institute of Technical Biochemistry; University of Stuttgart; Stuttgart Germany
| | - S.J. Facey
- Institute of Technical Biochemistry; University of Stuttgart; Stuttgart Germany
| | | | | | | | - J.G. Nijland
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology; Zernike Institute for Advanced Materials and Kluyver Centre for Genomics of Industrial Fermentation; University of Groningen; Groningen The Netherlands
| | - A.J.M. Driessen
- Molecular Microbiology, Groningen Biomolecular Sciences and Biotechnology; Zernike Institute for Advanced Materials and Kluyver Centre for Genomics of Industrial Fermentation; University of Groningen; Groningen The Netherlands
| | - B. Hauer
- Institute of Technical Biochemistry; University of Stuttgart; Stuttgart Germany
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10
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Mensonides FI, Hellingwerf KJ, de Mattos MJT, Brul S. Multiphasic adaptation of the transcriptome of Saccharomyces cerevisiae to heat stress. Food Res Int 2013. [DOI: 10.1016/j.foodres.2012.12.042] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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11
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Kim JH, Roy A, Jouandot D, Cho KH. The glucose signaling network in yeast. Biochim Biophys Acta Gen Subj 2013; 1830:5204-10. [PMID: 23911748 DOI: 10.1016/j.bbagen.2013.07.025] [Citation(s) in RCA: 88] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2013] [Revised: 07/24/2013] [Accepted: 07/26/2013] [Indexed: 01/26/2023]
Abstract
BACKGROUND Most cells possess a sophisticated mechanism for sensing glucose and responding to it appropriately. Glucose sensing and signaling in the budding yeast Saccharomyces cerevisiae represent an important paradigm for understanding how extracellular signals lead to changes in the gene expression program in eukaryotes. SCOPE OF REVIEW This review focuses on the yeast glucose sensing and signaling pathways that operate in a highly regulated and cooperative manner to bring about glucose-induction of HXT gene expression. MAJOR CONCLUSIONS The yeast cells possess a family of glucose transporters (HXTs), with different kinetic properties. They employ three major glucose signaling pathways-Rgt2/Snf3, AMPK, and cAMP-PKA-to express only those transporters best suited for the amounts of glucose available. We discuss the current understanding of how these pathways are integrated into a regulatory network to ensure efficient uptake and utilization of glucose. GENERAL SIGNIFICANCE Elucidating the role of multiple glucose signals and pathways involved in glucose uptake and metabolism in yeast may reveal the molecular basis of glucose homeostasis in humans, especially under pathological conditions, such as hyperglycemia in diabetics and the elevated rate of glycolysis observed in many solid tumors.
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Affiliation(s)
- Jeong-Ho Kim
- Department of Biochemistry and Molecular Medicine, The George Washington University Medical Center, 2300 Eye Street, Washington, DC 20037, USA.
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12
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Regulations of sugar transporters: insights from yeast. Curr Genet 2013; 59:1-31. [PMID: 23455612 DOI: 10.1007/s00294-013-0388-8] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2012] [Revised: 01/28/2013] [Accepted: 02/02/2013] [Indexed: 12/24/2022]
Abstract
Transport across the plasma membrane is the first step at which nutrient supply is tightly regulated in response to intracellular needs and often also rapidly changing external environment. In this review, I describe primarily our current understanding of multiple interconnected glucose-sensing systems and signal-transduction pathways that ensure fast and optimum expression of genes encoding hexose transporters in three yeast species, Saccharomyces cerevisiae, Kluyveromyces lactis and Candida albicans. In addition, an overview of GAL- and MAL-specific regulatory networks, controlling galactose and maltose utilization, is provided. Finally, pathways generating signals inducing posttranslational degradation of sugar transporters will be highlighted.
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13
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Aragon AD, Torrez-Martinez N, Edwards JS. Genomic analysis of Saccharomyces cerevisiae isolates that grow optimally with glucose as the sole carbon source. Electrophoresis 2012; 33:3514-20. [PMID: 23135695 DOI: 10.1002/elps.201200172] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Revised: 07/07/2012] [Accepted: 07/09/2012] [Indexed: 11/07/2022]
Abstract
A population of Saccharomyces cerevisiae was cultured for approximately 450 generations in the presence of high glucose to select for genetic variants that grew optimally under these conditions. Using the parental strain BY4741 as the starting population, an evolved culture was obtained after aerobic growth in a high glucose medium for approximately 450 generations. After the evolution period, three single colony isolates were selected for analysis. Next-generation Ion Torrent sequencing was used to evaluate genetic changes. Greater than 100 deletion/insertion changes were found with approximately half of these effecting genes. Additionally, over 180 SNPs were identified with more than one-quarter of these resulting in a nonsynonymous mutation. Affymetrix DNA microarrays and RNseq analysis were used to determine differences in gene expression in the evolved strains compared to the parental strain. It was established that approximately 900 genes demonstrated significantly altered expression in the evolved strains relative to the parental strain. Many of these genes showed similar alterations in their expression in all three evolved strains. Interestingly, genes with altered expression in the three evolved strains included genes with a role in oxidative metabolism. Overall these results are consistent with the physiological observations of optimal growth with glucose as the carbon source. Namely, the decreased ethanol production suggest that the underlying metabolism switched from fermentation to respiration during the selection for optimal growth on glucose.
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Affiliation(s)
- Anthony D Aragon
- UNM Department of Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, NM 87131, USA
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14
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Huberts DHEW, Niebel B, Heinemann M. A flux-sensing mechanism could regulate the switch between respiration and fermentation. FEMS Yeast Res 2011; 12:118-28. [DOI: 10.1111/j.1567-1364.2011.00767.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Revised: 10/28/2011] [Accepted: 11/16/2011] [Indexed: 12/20/2022] Open
Affiliation(s)
- Daphne H. E. W. Huberts
- Molecular Systems Biology; Groningen Biomolecular Sciences and Biotechnology Institute; University of Groningen; Groningen; The Netherlands
| | - Bastian Niebel
- Molecular Systems Biology; Groningen Biomolecular Sciences and Biotechnology Institute; University of Groningen; Groningen; The Netherlands
| | - Matthias Heinemann
- Molecular Systems Biology; Groningen Biomolecular Sciences and Biotechnology Institute; University of Groningen; Groningen; The Netherlands
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15
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Kasahara T, Shimogawara K, Kasahara M. Crucial effects of amino acid side chain length in transmembrane segment 5 on substrate affinity in yeast glucose transporter Hxt7. Biochemistry 2011; 50:8674-81. [PMID: 21892826 DOI: 10.1021/bi200958s] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We previously identified Asp(340) in transmembrane segment 7 (TM7) as a key determinant of substrate affinity in Hxt7, a high-affinity facilitative glucose transporter of Saccharomyces cerevisiae. To gain further insight into the structural basis of substrate recognition by Hxt7, we performed cysteine-scanning mutagenesis of 21 residues in TM5 of a Cys-less form of Hxt7. Four residues were sensitive to Cys replacement, among which Gln(209) was found to be essential for high-affinity glucose transport activity. The 17 remaining sites were examined further for the accessibility of cysteine to the hydrophilic sulfhydryl reagent p-chloromercuribenzenesulfonate (pCMBS). Among the Cys mutants, T213C was the only one whose transport activity was completely inhibited by 0.5 mM pCMBS. Moreover, this mutant was protected from pCMBS inhibition by the substrate d-glucose and by 2-deoxy-D-glucose but not by L-glucose, indicating that Thr(213) is situated at or close to a substrate recognition site. The functional role of Thr(213) was further examined with its replacement with each of the other 19 amino acids in wild-type Hxt7. Such replacement generated seven functional transporters with various affinities for glucose. Only three mutants, those with Val, Cys, and Ser at position 213, exhibited high-affinity glucose transport activity. All of these residues possess a side chain length similar to that of Thr, indicating that side chain length at this position is a key determinant of substrate affinity. A working homology model of Hxt7 indicated that Gln(209) and Thr(213) face the central cavity and that Thr(213) is located within van der Waals distance of Asp(340) (TM7).
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Affiliation(s)
- Toshiko Kasahara
- Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan.
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16
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Metabolic control analysis indicates a change of strategy in the treatment of cancer. Mitochondrion 2010; 10:626-39. [DOI: 10.1016/j.mito.2010.06.002] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2009] [Revised: 03/06/2010] [Accepted: 06/01/2010] [Indexed: 01/01/2023]
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17
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Lin Z, Li WH. Expansion of hexose transporter genes was associated with the evolution of aerobic fermentation in yeasts. Mol Biol Evol 2010; 28:131-42. [PMID: 20660490 DOI: 10.1093/molbev/msq184] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The genetic basis of organisms' adaptation to different environments is a central issue of molecular evolution. The budding yeast Saccharomyces cerevisiae and its relatives predominantly ferment glucose into ethanol even in the presence of oxygen. This was suggested to be an adaptation to glucose-rich habitats, but the underlying genetic basis of the evolution of aerobic fermentation remains unclear. In S. cerevisiae, the first step of glucose metabolism is transporting glucose across the plasma membrane, which is carried out by hexose transporter proteins. Although several studies have recognized that the rate of glucose uptake can affect how glucose is metabolized, the role of HXT genes in the evolution of aerobic fermentation has not been fully explored. In this study, we identified all members of the HXT gene family in 23 fully sequenced fungal genomes, reconstructed their evolutionary history to pinpoint gene gain and loss events, and evaluated their adaptive significance in the evolution of aerobic fermentation. We found that the HXT genes have been extensively amplified in the two fungal lineages that have independently evolved aerobic fermentation. In contrast, reduction of the number of HXT genes has occurred in aerobic respiratory species. Our study reveals a strong positive correlation between the copy number of HXT genes and the strength of aerobic fermentation, suggesting that HXT gene expansion has facilitated the evolution of aerobic fermentation.
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Affiliation(s)
- Zhenguo Lin
- Department of Ecology and Evolution, University of Chicago, USA
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18
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Busti S, Coccetti P, Alberghina L, Vanoni M. Glucose signaling-mediated coordination of cell growth and cell cycle in Saccharomyces cerevisiae. SENSORS 2010; 10:6195-240. [PMID: 22219709 PMCID: PMC3247754 DOI: 10.3390/s100606195] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/07/2010] [Revised: 05/26/2010] [Accepted: 05/27/2010] [Indexed: 01/05/2023]
Abstract
Besides being the favorite carbon and energy source for the budding yeast Sacchromyces cerevisiae, glucose can act as a signaling molecule to regulate multiple aspects of yeast physiology. Yeast cells have evolved several mechanisms for monitoring the level of glucose in their habitat and respond quickly to frequent changes in the sugar availability in the environment: the cAMP/PKA pathways (with its two branches comprising Ras and the Gpr1/Gpa2 module), the Rgt2/Snf3-Rgt1 pathway and the main repression pathway involving the kinase Snf1. The cAMP/PKA pathway plays the prominent role in responding to changes in glucose availability and initiating the signaling processes that promote cell growth and division. Snf1 (the yeast homologous to mammalian AMP-activated protein kinase) is primarily required for the adaptation of yeast cell to glucose limitation and for growth on alternative carbon source, but it is also involved in the cellular response to various environmental stresses. The Rgt2/Snf3-Rgt1 pathway regulates the expression of genes required for glucose uptake. Many interconnections exist between the diverse glucose sensing systems, which enables yeast cells to fine tune cell growth, cell cycle and their coordination in response to nutritional changes.
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Affiliation(s)
- Stefano Busti
- Dipartimento di Biotecnologie e Bioscienze, Università di Milano Bicocca, Piazza della Scienza, 2-20126 Milano, Italy.
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19
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Kasahara T, Kasahara M. Identification of a key residue determining substrate affinity in the yeast glucose transporter Hxt7: a two-dimensional comprehensive study. J Biol Chem 2010; 285:26263-8. [PMID: 20525688 DOI: 10.1074/jbc.m110.149716] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We previously identified Asn(331) in transmembrane segment 7 (TM7) as a key residue determining substrate affinity in Hxt2, a moderately high-affinity facilitative glucose transporter of Saccharomyces cerevisiae. To gain further insight into the structural basis of substrate recognition by yeast glucose transporters, we have now studied Hxt7, whose affinity for glucose is the highest among the major hexose transporters. The functional role of Asp(340) in Hxt7, the residue corresponding to Asn(331) of Hxt2, was examined by replacing it with each of the other 19 amino acids. Such replacement of Asp(340) generated transporters with various affinities for glucose, with the affinity of the Cys(340) mutant surpassing that of the wild-type Hxt7. To examine the structural role of Asp(340) in the substrate translocation pathway, we performed cysteine-scanning mutagenesis of the 21 residues in TM7 of a functional Cys-less Hxt7 mutant in conjunction with exposure to the hydrophilic sulfhydryl reagent p-chloromercuribenzenesulfonate (pCMBS). The transport activity of the D340C mutant of Cys-less Hxt7, in which Asp(340) is replaced with Cys, was completely inhibited by pCMBS, indicating that Asp(340) is located in a water-accessible position. This D340C mutant showed a sensitivity to pCMBS that was approximately 70 times that of the wild-type Hxt7, and it was protected from pCMBS inhibition by the substrates d-glucose and 2-deoxy-d-glucose but not by l-glucose. These results indicate that Asp(340) is situated at or close to a substrate recognition site and is a key residue determining high-affinity glucose transport by Hxt7, supporting the notion that yeast glucose transporters share a common mechanism for substrate recognition.
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Affiliation(s)
- Toshiko Kasahara
- Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan
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20
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Rossi G, Sauer M, Porro D, Branduardi P. Effect of HXT1 and HXT7 hexose transporter overexpression on wild-type and lactic acid producing Saccharomyces cerevisiae cells. Microb Cell Fact 2010; 9:15. [PMID: 20214823 PMCID: PMC2848207 DOI: 10.1186/1475-2859-9-15] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2009] [Accepted: 03/09/2010] [Indexed: 02/08/2023] Open
Abstract
Background Since about three decades, Saccharomyces cerevisiae can be engineered to efficiently produce proteins and metabolites. Even recognizing that in baker's yeast one determining step for the glucose consumption rate is the sugar uptake, this fact has never been conceived to improve the metabolite(s) productivity. In this work we compared the ethanol and/or the lactic acid production from wild type and metabolically engineered
S. cerevisiae cells expressing an additional copy of one hexose transporter. Results Different S. cerevisiae strains (wild type and metabolically engineered for lactic acid production) were transformed with the HXT1 or the HXT7 gene encoding for hexose transporters. Data obtained suggest that the overexpression of an Hxt transporter may lead to an increase in glucose uptake that could result in an increased ethanol and/or lactic acid productivities. As a consequence of the increased productivity and of the reduced process timing, a higher production was measured. Conclusion Metabolic pathway manipulation for improving the properties and the productivity of microorganisms is a well established concept. A high production relies on a multi-factorial system. We showed that by modulating the first step of the pathway leading to lactic acid accumulation an improvement of about 15% in lactic acid production can be obtained in a yeast strain already developed for industrial application.
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Affiliation(s)
- Giorgia Rossi
- Università degli Studi di Milano-Bicocca, Department of Biotechnology and Bioscience, Piazza della Scienza 2, Milan, Italy
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21
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Sauer M, Porro D, Mattanovich D, Branduardi P. 16 years research on lactic acid production with yeast – ready for the market? Biotechnol Genet Eng Rev 2010; 27:229-56. [DOI: 10.1080/02648725.2010.10648152] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
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22
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Groeneveld P, Stouthamer AH, Westerhoff HV. Super life--how and why 'cell selection' leads to the fastest-growing eukaryote. FEBS J 2009; 276:254-70. [PMID: 19087200 DOI: 10.1111/j.1742-4658.2008.06778.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
What is the highest possible replication rate for living organisms? The cellular growth rate is controlled by a variety of processes. Therefore, it is unclear which metabolic process or group of processes should be activated to increase growth rate. An organism that is already growing fast may already have optimized through evolution all processes that could be optimized readily, but may be confronted with a more generic limitation. Here we introduce a method called 'cell selection' to select for highest growth rate, and show how such a cellular site of 'growth control' was identified. By applying pH-auxostat cultivation to the already fast-growing yeast Kluyveromyces marxianus for a sufficiently long time, we selected a strain with a 30% increased growth rate; its cell-cycle time decreased to 52 min, much below that reported to date for any eukaryote. The increase in growth rate was accompanied by a 40% increase in cell surface at a fairly constant cell volume. We show how the increase in growth rate can be explained by a dominant (80%) limitation of growth by the group of membrane processes (a 0.7% increase of specific growth rate to a 1% increase in membrane surface area). Simultaneous activation of membrane processes may be what is required to accelerate growth of the fastest-growing form of eukaryotic life to growth rates that are even faster, and may be of potential interest for single-cell protein production in industrial 'White' biotechnology processes.
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Affiliation(s)
- Philip Groeneveld
- Department of Molecular Cell Physiology & Mathematical Biochemistry, Netherlands Institute for Systems Biology, Vrije Universiteit, Amsterdam, The Netherlands
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23
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Barnett JA. A history of research on yeasts 13. Active transport and the uptake of various metabolites. Yeast 2008; 25:689-731. [PMID: 18951365 DOI: 10.1002/yea.1630] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- James A Barnett
- School of Biological Sciences, University of East Anglia, Norwich, UK.
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24
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Craig Maclean R, Brandon C. Stable public goods cooperation and dynamic social interactions in yeast. J Evol Biol 2008; 21:1836-43. [PMID: 18643862 DOI: 10.1111/j.1420-9101.2008.01579.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Despite long-standing theoretical interest in the evolution of cooperation, empirical data on the evolutionary dynamics of cooperative traits remain limited. Here, we investigate the evolutionary dynamics of a simple public goods cooperative trait, invertase secretion, using a long-term selection experiment in Saccharomyces cerevisiae. We show that average investment in cooperation remains essentially constant over a period of hundreds of generations in viscous populations with high relatedness. Average cooperation remains constant despite transient local selection for high and low levels of cooperation that generate dynamic social interactions. Natural populations of yeast show similar variation in social strategies, which is consistent with the existence of similar selective pressures on public goods cooperation in nature.
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Affiliation(s)
- R Craig Maclean
- NERC Centre for Population Biology, Imperial College London, Silwood Park, Ascot, UK.
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25
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Ståhlberg A, Elbing K, Andrade-Garda JM, Sjögreen B, Forootan A, Kubista M. Multiway real-time PCR gene expression profiling in yeast Saccharomyces cerevisiae reveals altered transcriptional response of ADH-genes to glucose stimuli. BMC Genomics 2008; 9:170. [PMID: 18412983 PMCID: PMC2335116 DOI: 10.1186/1471-2164-9-170] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2007] [Accepted: 04/16/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The large sensitivity, high reproducibility and essentially unlimited dynamic range of real-time PCR to measure gene expression in complex samples provides the opportunity for powerful multivariate and multiway studies of biological phenomena. In multiway studies samples are characterized by their expression profiles to monitor changes over time, effect of treatment, drug dosage etc. Here we perform a multiway study of the temporal response of four yeast Saccharomyces cerevisiae strains with different glucose uptake rates upon altered metabolic conditions. RESULTS We measured the expression of 18 genes as function of time after addition of glucose to four strains of yeast grown in ethanol. The data are analyzed by matrix-augmented PCA, which is a generalization of PCA for 3-way data, and the results are confirmed by hierarchical clustering and clustering by Kohonen self-organizing map. Our approach identifies gene groups that respond similarly to the change of nutrient, and genes that behave differently in mutant strains. Of particular interest is our finding that ADH4 and ADH6 show a behavior typical of glucose-induced genes, while ADH3 and ADH5 are repressed after glucose addition. CONCLUSION Multiway real-time PCR gene expression profiling is a powerful technique which can be utilized to characterize functions of new genes by, for example, comparing their temporal response after perturbation in different genetic variants of the studied subject. The technique also identifies genes that show perturbed expression in specific strains.
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26
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Rintala E, Wiebe MG, Tamminen A, Ruohonen L, Penttilä M. Transcription of hexose transporters of Saccharomyces cerevisiae is affected by change in oxygen provision. BMC Microbiol 2008; 8:53. [PMID: 18373847 PMCID: PMC2324102 DOI: 10.1186/1471-2180-8-53] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2007] [Accepted: 03/28/2008] [Indexed: 12/03/2022] Open
Abstract
Background The gene family of hexose transporters in Saccharomyces cerevisiae consists of 20 members; 18 genes encoding transporters (HXT1-HXT17, GAL2) and two genes encoding sensors (SNF3, RGT2). The effect of oxygen provision on the expression of these genes was studied in glucose-limited chemostat cultivations (D = 0.10 h-1, pH 5, 30°C). Transcript levels were measured from cells grown in five steady state oxygen levels (0, 0.5, 1, 2.8 and 20.9% O2), and from cells under conditions in which oxygen was introduced to anaerobic cultures or removed from cultures receiving oxygen. Results The expression pattern of the HXT gene family was distinct in cells grown under aerobic, hypoxic and anaerobic conditions. The transcription of HXT2, HXT4 and HXT5 was low when the oxygen concentration in the cultures was low, both under steady state and non-steady state conditions, whereas the expression of HXT6, HXT13 and HXT15/16 was higher in hypoxic than in fully aerobic or anaerobic conditions. None of the HXT genes showed higher transcript levels in strictly anaerobic conditions. Expression of HXT9, HXT14 and GAL2 was not detected under the culture conditions studied. Conclusion When oxygen becomes limiting in a glucose-limited chemostat cultivation, the glucose uptake rate per cell increases. However, the expression of none of the hexose transporter encoding genes was increased in anaerobic conditions. It thus seems that the decrease in the moderately low affinity uptake and consequently the relative increase of high affinity uptake may itself allow the higher specific glucose consumption rate to occur in anaerobic compared to aerobic conditions.
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Affiliation(s)
- Eija Rintala
- VTT, Technical Research Centre of Finland, PO Box 1000, FI-02044 VTT, Finland.
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27
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Identification of hexose transporter-like sensor HXS1 and functional hexose transporter HXT1 in the methylotrophic yeast Hansenula polymorpha. EUKARYOTIC CELL 2008; 7:735-46. [PMID: 18310355 DOI: 10.1128/ec.00028-08] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
We identified in the methylotrophic yeast Hansenula polymorpha (syn. Pichia angusta) a novel hexose transporter homologue gene, HXS1 (hexose sensor), involved in transcriptional regulation in response to hexoses, and a regular hexose carrier gene, HXT1 (hexose transporter). The Hxs1 protein exhibits the highest degree of primary sequence similarity to the Saccharomyces cerevisiae transporter-like glucose sensors, Snf3 and Rgt2. When heterologously overexpressed in an S. cerevisiae hexose transporter-less mutant, Hxt1, but not Hxs1, restores growth on glucose or fructose, suggesting that Hxs1 is nonfunctional as a carrier. In its native host, HXS1 is expressed at moderately low level and is required for glucose induction of the H. polymorpha functional low-affinity glucose transporter Hxt1. Similarly to other yeast sensors, one conserved amino acid substitution in the Hxs1 sequence (R203K) converts the protein into a constitutively signaling form and the C-terminal region of Hxs1 is essential for its function in hexose sensing. Hxs1 is not required for glucose repression or catabolite inactivation that involves autophagic degradation of peroxisomes. However, HXS1 deficiency leads to significantly impaired transient transcriptional repression in response to fructose, probably due to the stronger defect in transport of this hexose in the hxs1Delta deletion strain. Our combined results suggest that in the Crabtree-negative yeast H. polymorpha, the single transporter-like sensor Hxs1 mediates signaling in the hexose induction pathway, whereas the rate of hexose uptake affects the strength of catabolite repression.
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28
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Gutiérrez-Lomelí M, Torres-Guzmán JC, González-Hernández GA, Cira-Chávez LA, Pelayo-Ortiz C, Ramírez-Córdova JDJ. Overexpression of ADH1 and HXT1 genes in the yeast Saccharomyces cerevisiae improves the fermentative efficiency during tequila elaboration. Antonie van Leeuwenhoek 2008; 93:363-71. [DOI: 10.1007/s10482-007-9213-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2007] [Accepted: 11/22/2007] [Indexed: 10/22/2022]
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Belinchón MM, Gancedo JM. Glucose controls multiple processes inSaccharomyces cerevisiaethrough diverse combinations of signaling pathways. FEMS Yeast Res 2007; 7:808-18. [PMID: 17428308 DOI: 10.1111/j.1567-1364.2007.00236.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
We have studied how the lack of glucose sensors in the plasma membrane, or of the enzymes Hxk1, Hxk2, Glk1, which catalyze the first intracellular step in glucose metabolism, affect the different responses of Saccharomyces cerevisiae to glucose. Lack of the G-protein-coupled receptor Gpr1 or of Snf3/Rgt2 did not affect glucose repression of different genes or activation by glucose of plasma membrane ATPase, whereas lack of Gpr1 decreased, in an additive manner with lack of Mth1, the degradation of fructose 1,6-bisphosphatase that takes place in the presence of glucose. In an hxk1 hxk2 glk1 strain, unable to phosphorylate glucose, all of these responses to the sugar were suppressed or strongly reduced. In the absence of Hxk2 (or Hxk1 and Hxk2), glucose repression of SUC2, GAL1 and GDH2 was relieved, but that of FBP1 and ICL1 was maintained. Hxk1 or Hxk2 were needed for activation of plasma membrane ATPase but not for degradation of FbPase.
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Affiliation(s)
- Mónica M Belinchón
- Instituto de Investigaciones Biomédicas Alberto Sols, CSIC-UAM, Arturo Duperier, Madrid, Spain
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30
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Alves-Araújo C, Pacheco A, Almeida MJ, Spencer-Martins I, Leão C, Sousa MJ. Sugar utilization patterns and respiro-fermentative metabolism in the baker's yeast Torulaspora delbrueckii. MICROBIOLOGY-SGM 2007; 153:898-904. [PMID: 17322210 DOI: 10.1099/mic.0.2006/003475-0] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The highly osmo- and cryotolerant yeast species Torulaspora delbrueckii is an important case study among the non-Saccharomyces yeast species. The strain T. delbrueckii PYCC 5321, isolated from traditional corn and rye bread dough in northern Portugal, is considered particularly interesting for the baking industry. This paper reports the sugar utilization patterns of this strain, using media with glucose, maltose and sucrose, alone or in mixtures. Kinetics of growth, biomass and ethanol yields, fermentation and respiration rates, hydrolase activities and sugar uptake rates were used to infer the potential applied relevance of this yeast in comparison to a conventional baker's strain of Saccharomyces cerevisiae. The results showed that both maltase and maltose transport in T. delbrueckii were subject to glucose repression and maltose induction, whereas invertase was subject to glucose control but not dependent on sucrose induction. A comparative analysis of specific sugar consumption rates and transport capacities suggests that the transport step limits both glucose and maltose metabolism. Specific rates of CO(2) production and O(2) consumption showed a significantly higher contribution of respiration to the overall metabolism in T. delbrueckii than in S. cerevisiae. This was reflected in the biomass yields from batch cultures and could represent an asset for the large-scale production of the former species. This work contributes to a better understanding of the physiology of a non-conventional yeast species, with a view to the full exploitation of T. delbrueckii by the baking industry.
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Affiliation(s)
- C Alves-Araújo
- Center of Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - A Pacheco
- Center of Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - M J Almeida
- Center of Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - I Spencer-Martins
- Centro de Recursos Microbiológicos (CREM), Biotechnology Unit, Faculty of Sciences and Technology, New University of Lisbon, 2829-516 Caparica, Portugal
| | - C Leão
- Life and Health Sciences Research Institute (ICVS), School of Health Sciences, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
| | - M J Sousa
- Center of Biology, Department of Biology, University of Minho, Campus de Gualtar, 4710-057 Braga, Portugal
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31
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Kasahara T, Maeda M, Ishiguro M, Kasahara M. Identification by Comprehensive Chimeric Analysis of a Key Residue Responsible for High Affinity Glucose Transport by Yeast HXT2. J Biol Chem 2007; 282:13146-50. [PMID: 17369259 DOI: 10.1074/jbc.c700041200] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Hxt2 and Hxt1 are, respectively, high affinity and low affinity facilitative glucose transporter paralogs of Saccharomyces cerevisiae. We have previously investigated which amino acid residues of Hxt2 are important for high affinity transport activity. Studies with all the possible combinations of 12 transmembrane segments (TMs) of Hxt2 and Hxt1 revealed that TMs 1, 5, 7, and 8 of Hxt2 are necessary for high affinity transport. Systematic shuffling of the 20 amino acid residues that differ between Hxt2 and Hxt1 in these TMs subsequently identified 5 residues as important for such activity: Leu(59) and Leu(61) (TM1), Leu(201) (TM5), Asn(331) (TM7), and Phe(366) (TM8). We have now studied the relative importance of these 5 residues by individually replacing them with each of the other 19 residues. Replacement of Asn(331) yielded transporters with various affinities, with those of the Ile(331), Val(331), and Cys(331) mutants being higher than that of the wild type. Replacement of the Hxt2 residues at the other four sites yielded transporters with affinities similar to that of the wild type but with various capacities. A working homology model of the chimeric transporters containing Asn(331) or its 19 replacement residues indicated that those residues at this site that yield high affinity transporters (Ile(331), Val(331), Cys(331)) face the central cavity and are within van der Waals distances of Phe(208) (TM5), Leu(357) (TM8), and Tyr(427) (TM10). Interactions via these residues of the four TMs, which compose a half of the central pore, may thus play a pivotal role in formation of a core structure for high affinity transport.
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Affiliation(s)
- Toshiko Kasahara
- Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395
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32
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Rodaki A, Young T, Brown AJP. Effects of depleting the essential central metabolic enzyme fructose-1,6-bisphosphate aldolase on the growth and viability of Candida albicans: implications for antifungal drug target discovery. EUKARYOTIC CELL 2007; 5:1371-7. [PMID: 16896220 PMCID: PMC1539134 DOI: 10.1128/ec.00115-06] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The central metabolic enzyme fructose-1,6-bisphosphate aldolase (Fba1p) catalyzes a reversible reaction required for both glycolysis and gluconeogenesis. Fba1p is a potential antifungal target because it is essential in yeast and because fungal and human aldolases differ significantly. To test the validity of Fba1p as an antifungal target, we have examined the effects of depleting this enzyme in the major fungal pathogen Candida albicans. Using a methionine/cysteine-conditional mutant (MET3-FBA1/fba1), we have shown that Fba1p is required for the growth of C. albicans. However, Fba1p must be depleted to below 5% of wild-type levels before growth is blocked. Furthermore, Fba1p depletion exerts static rather than cidal effects upon C. albicans. Fba1p is a relatively abundant and stable protein in C. albicans, and hence, Fba1p levels decay relatively slowly following MET3-FBA1 shutoff. Taken together, our observations can account for our observation that the virulence of MET3-FBA1/fba1 cells is only partially attenuated in the mouse model of systemic candidiasis. We conclude that an antifungal drug directed against Fba1p would have to be potent to be effective.
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Affiliation(s)
- Alexandra Rodaki
- Aberdeen Fungal Group, School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Aberdeen AB25 2ZD, United Kingdom
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Saloheimo A, Rauta J, Stasyk OV, Sibirny AA, Penttilä M, Ruohonen L. Xylose transport studies with xylose-utilizing Saccharomyces cerevisiae strains expressing heterologous and homologous permeases. Appl Microbiol Biotechnol 2006; 74:1041-52. [PMID: 17180689 DOI: 10.1007/s00253-006-0747-1] [Citation(s) in RCA: 137] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2006] [Revised: 10/18/2006] [Accepted: 11/05/2006] [Indexed: 11/29/2022]
Abstract
In the present study, we modified xylose uptake properties of a recombinant xylose-utilizing yeast Saccharomyces cerevisiae by expression of heterologous and homologous permease-encoding genes. In a mutant yeast strain with the main seven hexose transporter genes deleted, and engineered for xylose utilization, we screened an expression cDNA library of the filamentous fungus Trichoderma reesei (Hypocrea jecorina) for enhanced growth on xylose plates. One cDNA clone with significant homology to fungal sugar transporters was obtained, but when the clone was retransformed into the host, it did not support significant growth on xylose. However, during a long liquid culture of the strain carrying the cDNA clone, adaptive mutations apparently occurred in the host, which led to growth on xylose but not on glucose. The new transporter homologue, Trxlt1 thus appears to code for a protein specific for xylose uptake. In addition, xylose-transporting properties of some homologous hexose transporters were studied. All of them, i.e., Hxt1, Hxt2, Hxt4, and Hxt7 were capable of xylose uptake. Their affinities for xylose varied, K (m) values between 130 and 900 mM were observed. The single-Hxt strains showed a biphasic growth mode on xylose, alike the Trxlt1 harboring strain. The initial, slow growth was followed by a long lag and finally by exponential growth.
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Affiliation(s)
- Anu Saloheimo
- VTT, Technical Research Centre of Finland, PO Box 1000, Espoo, FI-02044, Finland.
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Kasahara T, Ishiguro M, Kasahara M. Eight amino acid residues in transmembrane segments of yeast glucose transporter Hxt2 are required for high affinity transport. J Biol Chem 2006; 281:18532-8. [PMID: 16636054 DOI: 10.1074/jbc.m602123200] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Hxt2 and Hxt1 are high affinity and low affinity facilitative glucose transporter paralogs of Saccharomyces cerevisiae, respectively, that differ at 75 amino acid positions in their 12 transmembrane segments (TMs). Comprehensive analysis of chimeras of these two proteins has previously revealed that TMs 1, 5, 7, and 8 of Hxt2 are required for high affinity glucose transport activity and that leucine 201 in TM5 is the most important in this regard of the 20 amino acid residues in these regions that differ between Hxt2 and Hxt1. To evaluate the importance of the remaining residues, we systematically shuffled the amino acids at these positions and screened the resulting proteins for high affinity and high capacity glucose transport activity. In addition to leucine 201 (TM5), four residues of Hxt2 (leucine 59 and leucine 61 in TM1, asparagine 331 in TM7, and phenylalanine 366 in TM8) were found to be important for such activity. Furthermore, phenylalanine 198 (TM5), alanine 363 (TM8), and either valine 316 (TM7) or alanine 368 (TM8) were found to be supportive of maximal activity. Construction of a homology model suggested that asparagine 331 interacts directly with the substrate and that the other identified residues may contribute to maintenance of protein conformation.
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Affiliation(s)
- Toshiko Kasahara
- Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan
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35
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Henricsson C, de Jesus Ferreira MC, Hedfalk K, Elbing K, Larsson C, Bill RM, Norbeck J, Hohmann S, Gustafsson L. Engineering of a novel Saccharomyces cerevisiae wine strain with a respiratory phenotype at high external glucose concentrations. Appl Environ Microbiol 2005; 71:6185-92. [PMID: 16204537 PMCID: PMC1265946 DOI: 10.1128/aem.71.10.6185-6192.2005] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The recently described respiratory strain Saccharomyces cerevisiae KOY.TM6*P is, to our knowledge, the only reported strain of S. cerevisiae which completely redirects the flux of glucose from ethanol fermentation to respiration, even at high external glucose concentrations (27). In the KOY.TM6*P strain, portions of the genes encoding the predominant hexose transporter proteins, Hxt1 and Hxt7, were fused within the regions encoding transmembrane (TM) domain 6. The resulting chimeric gene, TM6*, encoded a chimera composed of the amino-terminal half of Hxt1 and the carboxy-terminal half of Hxt7. It was subsequently integrated into the genome of an hxt null strain. In this study, we have demonstrated the transferability of this respiratory phenotype to the V5 hxt1-7Delta strain, a derivative of a strain used in enology. We also show by using this mutant that it is not necessary to transform a complete hxt null strain with the TM6* construct to obtain a non-ethanol-producing phenotype. The resulting V5.TM6*P strain, obtained by transformation of the V5 hxt1-7Delta strain with the TM6* chimeric gene, produced only minor amounts of ethanol when cultured on external glucose concentrations as high as 5%. Despite the fact that glucose flux was reduced to 30% in the V5.TM6*P strain compared with that of its parental strain, the V5.TM6*P strain produced biomass at a specific rate as high as 85% that of the V5 wild-type strain. Even more relevant for the potential use of such a strain for the production of heterologous proteins and also of low-alcohol beverages is the observation that the biomass yield increased 50% with the mutant compared to its parental strain.
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Affiliation(s)
- C Henricsson
- Department of Chemistry and Bioscience-Molecular Biotechnology, Chalmers University of Technology, Box 462, SE-405 30 Göteborg, Sweden
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36
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Elbing K, Ståhlberg A, Hohmann S, Gustafsson L. Transcriptional responses to glucose at different glycolytic rates in Saccharomyces cerevisiae. ACTA ACUST UNITED AC 2004; 271:4855-64. [PMID: 15606773 DOI: 10.1111/j.1432-1033.2004.04451.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The addition of glucose to Saccharomyces cerevisiae cells causes reprogramming of gene expression. Glucose is sensed by membrane receptors as well as (so far elusive) intracellular sensing mechanisms. The availability of four yeast strains that display different hexose uptake capacities allowed us to study glucose-induced effects at different glycolytic rates. Rapid glucose responses were observed in all strains able to take up glucose, consistent with intracellular sensing. The degree of long-term responses, however, clearly correlated with the glycolytic rate: glucose-stimulated expression of genes encoding enzymes of the lower part of glycolysis showed an almost linear correlation with the glycolytic rate, while expression levels of genes encoding gluconeogenic enzymes and invertase (SUC2) showed an inverse correlation. Glucose control of SUC2 expression is mediated by the Snf1-Mig1 pathway. Mig1 dephosphorylation upon glucose addition is known to lead to repression of target genes. Mig1 was initially dephosphorylated upon glucose addition in all strains able to take up glucose, but remained dephosphorylated only at high glycolytic rates. Remarkably, transient Mig1-dephosphorylation was accompanied by the repression of SUC2 expression at high glycolytic rates, but stimulated SUC2 expression at low glycolytic rates. This suggests that Mig1-mediated repression can be overruled by factors mediating induction via a low glucose signal. At low and moderate glycolytic rates, Mig1 was partly dephosphorylated both in the presence of phosphorylated, active Snf1, and unphosphorylated, inactive Snf1, indicating that Mig1 was actively phosphorylated and dephosphorylated simultaneously, suggesting independent control of both processes. Taken together, it appears that glucose addition affects the expression of SUC2 as well as Mig1 activity by both Snf1-dependent and -independent mechanisms that can now be dissected and resolved as early and late/sustained responses.
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Affiliation(s)
- Karin Elbing
- Department of Chemistry and Bioscience-Molecular Biotechnology, Chalmers University of Technology, Göteborg, Sweden.
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37
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Elbing K, Larsson C, Bill RM, Albers E, Snoep JL, Boles E, Hohmann S, Gustafsson L. Role of hexose transport in control of glycolytic flux in Saccharomyces cerevisiae. Appl Environ Microbiol 2004; 70:5323-30. [PMID: 15345416 PMCID: PMC520882 DOI: 10.1128/aem.70.9.5323-5330.2004] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The yeast Saccharomyces cerevisiae predominantly ferments glucose to ethanol at high external glucose concentrations, irrespective of the presence of oxygen. In contrast, at low external glucose concentrations and in the presence of oxygen, as in a glucose-limited chemostat, no ethanol is produced. The importance of the external glucose concentration suggests a central role for the affinity and maximal transport rates of yeast's glucose transporters in the control of ethanol production. Here we present a series of strains producing functional chimeras between the hexose transporters Hxt1 and Hxt7, each of which has distinct glucose transport characteristics. The strains display a range of decreasing glycolytic rates resulting in a proportional decrease in ethanol production. Using these strains, we show for the first time that at high glucose levels, the glucose uptake capacity of wild-type S. cerevisiae does not control glycolytic flux during exponential batch growth. In contrast, our chimeric Hxt transporters control the rate of glycolysis to a high degree. Strains whose glucose uptake is mediated by these chimeric transporters will undoubtedly provide a powerful tool with which to examine in detail the mechanism underlying the switch between fermentation and respiration in S. cerevisiae and will provide new tools for the control of industrial fermentations.
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Affiliation(s)
- Karin Elbing
- Department of Chemistry and Bioscience-Molecular Biotechnology, Chalmers University of Technology, Box 462, SE-405 30 Göteborg, Sweden.
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Blank LM, Sauer U. TCA cycle activity in Saccharomyces cerevisiae is a function of the environmentally determined specific growth and glucose uptake rates. MICROBIOLOGY-SGM 2004; 150:1085-1093. [PMID: 15073318 DOI: 10.1099/mic.0.26845-0] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Metabolic responses of Saccharomyces cerevisiae to different physical and chemical environmental conditions were investigated in glucose batch culture by GC-MS-detected mass isotopomer distributions in proteinogenic amino acids from (13)C-labelling experiments. For this purpose, GC-MS-based metabolic flux ratio analysis was extended from bacteria to the compartmentalized metabolism of S. cerevisiae. Generally, S. cerevisiae was shown to have low catabolic fluxes through the pentose phosphate pathway and the tricarboxylic acid (TCA) cycle. Notably, respiratory TCA cycle fluxes exhibited a strong correlation with the maximum specific growth rate that was attained under different environmental conditions, including a wide range of pH, osmolarity, decoupler and salt concentrations, but not temperature. At pH values of 4.0 to 6.0 with near-maximum growth rates, the TCA cycle operated as a bifurcated pathway to fulfil exclusively biosynthetic functions. Increasing or decreasing the pH beyond this physiologically optimal range, however, reduced growth and glucose uptake rates but increased the 'cyclic' respiratory mode of TCA cycle operation for catabolism. Thus, the results indicate that glucose repression of the TCA cycle is regulated by the rates of growth or glucose uptake, or signals derived from these. While sensing of extracellular glucose concentrations has a general influence on the in vivo TCA cycle activity, the growth-rate-dependent increase in respiratory TCA cycle activity was independent of glucose sensing.
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Affiliation(s)
- Lars M Blank
- Institute of Biotechnology, ETH Zürich, Zürich, Switzerland
| | - Uwe Sauer
- Institute of Biotechnology, ETH Zürich, Zürich, Switzerland
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Kasahara T, Ishiguro M, Kasahara M. Comprehensive Chimeric Analysis of Amino Acid Residues Critical for High Affinity Glucose Transport by Hxt2 of Saccharomyces cerevisiae. J Biol Chem 2004; 279:30274-8. [PMID: 15128737 DOI: 10.1074/jbc.m403762200] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Chimeras of Hxt2 and Hxt1, high affinity and low affinity glucose transporters, respectively, of Saccharomyces cerevisiae, were previously constructed by random replacement of each of the 12 transmembrane segments (TMs) of Hxt2 with the corresponding region of Hxt1. Characterization of these chimeras revealed that at least TMs 1, 5, 7, and 8 of Hxt2 are required for high affinity transport activity. To determine which amino acid residues in these TMs are important for high affinity glucose transport, we systematically shuffled all of the 20 residues in these regions that differ between Hxt2 and Hxt1. Analysis of 60 independent mutant strains identified as expressing high affinity and high capacity glucose transport activity by selection on glucose-limited agar plates revealed that Leu-201 in TM5 of Hxt2 is most important for such activity and that either Cys-195 or Phe-198 is also required for maximal activity.
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Affiliation(s)
- Toshiko Kasahara
- Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan.
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40
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Otterstedt K, Larsson C, Bill RM, Ståhlberg A, Boles E, Hohmann S, Gustafsson L. Switching the mode of metabolism in the yeast Saccharomyces cerevisiae. EMBO Rep 2004; 5:532-7. [PMID: 15071495 PMCID: PMC1299050 DOI: 10.1038/sj.embor.7400132] [Citation(s) in RCA: 149] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Revised: 02/25/2004] [Accepted: 02/26/2004] [Indexed: 11/08/2022] Open
Abstract
The biochemistry of most metabolic pathways is conserved from bacteria to humans, although the control mechanisms are adapted to the needs of each cell type. Oxygen depletion commonly controls the switch from respiration to fermentation. However, Saccharomyces cerevisiae also controls that switch in response to the external glucose level. We have generated an S. cerevisiae strain in which glucose uptake is dependent on a chimeric hexose transporter mediating reduced sugar uptake. This strain shows a fully respiratory metabolism also at high glucose levels as seen for aerobic organisms, and switches to fermentation only when oxygen is lacking. These observations illustrate that manipulating a single step can alter the mode of metabolism. The novel yeast strain is an excellent tool to study the mechanisms underlying glucose-induced signal transduction.
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Affiliation(s)
- Karin Otterstedt
- Department of Chemistry and Bioscience-Molecular Biotechnology, Chalmers University of Technology, Box 462, SE-405 30, Göteborg, Sweden.
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41
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Stasyk OV, Stasyk OG, Komduur J, Veenhuis M, Cregg JM, Sibirny AA. A hexose transporter homologue controls glucose repression in the methylotrophic yeast Hansenula polymorpha. J Biol Chem 2003; 279:8116-25. [PMID: 14660581 DOI: 10.1074/jbc.m310960200] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Peroxisome biogenesis and synthesis of peroxisomal enzymes in the methylotrophic yeast Hansenula polymorpha are under the strict control of glucose repression. We identified an H. polymorpha glucose catabolite repression gene (HpGCR1) that encodes a hexose transporter homologue. Deficiency in GCR1 leads to a pleiotropic phenotype that includes the constitutive presence of peroxisomes and peroxisomal enzymes in glucose-grown cells. Glucose transport and repression defects in a UV-induced gcr1-2 mutant were found to result from a missense point mutation that substitutes a serine residue (Ser(85)) with a phenylalanine in the second predicted transmembrane segment of the Gcr1 protein. In addition to glucose, mannose and trehalose fail to repress the peroxisomal enzyme, alcohol oxidase in gcr1-2 cells. A mutant deleted for the GCR1 gene was additionally deficient in fructose repression. Ethanol, sucrose, and maltose continue to repress peroxisomes and peroxisomal enzymes normally and therefore, appear to have GCR1-independent repression mechanisms in H. polymorpha. Among proteins of the hexose transporter family of baker's yeast, Saccharomyces cerevisiae, the amino acid sequence of the H. polymorpha Gcr1 protein shares the highest similarity with a core region of Snf3p, a putative high affinity glucose sensor. Certain features of the phenotype exhibited by gcr1 mutants suggest a regulatory role for Gcr1p in a repression pathway, along with involvement in hexose transport.
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Affiliation(s)
- Oleh V Stasyk
- Institute of Cell Biology, National Academy of Sciences of Ukraine, Drahomanov Street 14/16, Lviv 79005, Ukraine
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42
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Kasahara T, Kasahara M. Transmembrane segments 1, 5, 7 and 8 are required for high-affinity glucose transport by Saccharomyces cerevisiae Hxt2 transporter. Biochem J 2003; 372:247-52. [PMID: 12603199 PMCID: PMC1223383 DOI: 10.1042/bj20030044] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2003] [Revised: 02/17/2003] [Accepted: 02/25/2003] [Indexed: 11/17/2022]
Abstract
Hxt2 is a high-affinity facilitative glucose transporter of Saccharomyces cerevisiae and belongs to the major facilitator superfamily. Hxt1 shares approximately 70% amino acid identity with Hxt2 in its transmembrane segments (TMs) and inter-TM loops, but transports D-glucose with an affinity about one-tenth of that of Hxt2. To determine which TMs of Hxt2 are important for high-affinity glucose transport, we constructed chimaeras of Hxt2 and Hxt1 by randomly replacing each of the 12 TMs of Hxt2 with the corresponding segment of Hxt1, for a total of 4096 different transporters. Among > 20000 yeast transformants screened, 39 different clones were selected by plate assays of high-affinity glucose-transport activity and sequenced. With only two exceptions, the selected chimaeras contained Hxt2 TMs 1, 5, 7 and 8. We then constructed chimaeras corresponding to all 16 possible combinations of Hxt2 TMs 1, 5, 7 and 8. Only one chimaera, namely that containing all four Hxt2 TMs, exhibited transport activity comparable with that of Hxt2. The K (m) and V (max) values for D-glucose transport, and the substrate specificity of this chimaera were almost identical with those of Hxt2. These results indicate that TMs 1, 5, 7 and 8 are necessary for exhibiting high-affinity glucose-transport activity of Hxt2.
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Affiliation(s)
- Toshiko Kasahara
- Laboratory of Biophysics, School of Medicine, Teikyo University, Hachioji, Tokyo 192-0395, Japan
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43
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Yin Z, Wilson S, Hauser NC, Tournu H, Hoheisel JD, Brown AJP. Glucose triggers different global responses in yeast, depending on the strength of the signal, and transiently stabilizes ribosomal protein mRNAs. Mol Microbiol 2003; 48:713-24. [PMID: 12694616 DOI: 10.1046/j.1365-2958.2003.03478.x] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Glucose exerts profound effects upon yeast physiology. In general, the effects of high glucose concentrations (>1%) upon Saccharomyces cerevisiae have been studied. In this paper, we have characterized the global responses of yeast cells to very low (0.01%), low (0.1%) and high glucose signals (1.0%) by transcript profiling. We show that yeast is more sensitive to very low glucose signals than was previously thought, and that yeast displays different responses to these different glucose signals. Genes involved in central metabolic pathways respond rapidly to very low glucose signals, whereas genes involved in the biogenesis of cytoplasmic ribosomes generally respond only to glucose concentrations of> 0.1%. We also show that cytoplasmic ribosomal protein mRNAs are transiently stabilized by glucose, indicating that both transcriptional and post-transcriptional mechanisms combine to accelerate the accumulation of ribosomal protein mRNAs. Presumably, this facilitates rapid ribosome biogenesis after exposure to glucose. However, our data indicate that yeast activates ribosome biogenesis only when sufficient glucose is available to make this metabolic investment worthwhile. In contrast, the regulation of metabolic functions in response to very low glucose signals presumably ensures that yeast can exploit even minute amounts of this preferred nutrient.
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Affiliation(s)
- Zhikang Yin
- Department of Molecular and Cell Biology, University of Aberdeen, Institute of Medical Sciences, Foresterhill, Aberdeen AB25 2ZD, UK
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44
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Gárdonyi M, Osterberg M, Rodrigues C, Spencer-Martins I, Hahn-Hägerdal B. High capacity xylose transport in Candida intermedia PYCC 4715. FEMS Yeast Res 2003; 3:45-52. [PMID: 12702245 DOI: 10.1111/j.1567-1364.2003.tb00137.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Xylose-utilising yeasts were screened to identify strains with high xylose transport capacity. Among the fastest-growing strains in xylose medium, Candida intermedia PYCC 4715 showed the highest xylose transport capacity. Maximal specific growth rate was the same in glucose and xylose media (mu(max)=0.5 h-1, 30 degrees C). Xylose transport showed biphasic kinetics when cells were grown in either xylose- or glucose-limited culture. The high-affinity xylose/proton symport system (Km = 0.2 mM, Vmax = 7.5 mmol h-1 g-1) was more repressed by glucose than by xylose. The less specific low-affinity transport system (K = 50 mM, Vmax = 11 mmol h-1 g-1) appeared to operate through a facilitated-diffusion mechanism and was expressed constitutively. Inhibition experiments showed that glucose is a substrate of both xylose transport systems.
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Affiliation(s)
- Márk Gárdonyi
- Centro de Recursos Microbiológicos (CREM), Faculty of Sciences and Technology, New University of Lisbon, 2829-516, Caparica, Portugal
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45
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Ozcan S. Two different signals regulate repression and induction of gene expression by glucose. J Biol Chem 2002; 277:46993-7. [PMID: 12351652 DOI: 10.1074/jbc.m208726200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In addition to being the universal carbon and energy source, glucose also regulates gene expression in many organisms. In the yeast Saccharomyces cerevisiae glucose regulates gene expression via two different pathways known as the glucose repression and glucose induction pathways. The signal for glucose induction of hexose transporter (HXT) genes is generated via two glucose-transporter like molecules, Snf3 and Rgt2. A strain lacking both sensors is unable to induce HXT gene expression and is defective in glucose uptake. The snf3 rgt2 double mutant is also defective in glucose repression of transcription, raising the possibility that Snf3 and Rgt2 are also involved in generating the glucose repression signal. In this report, I show that induction and repression of gene expression by glucose in yeast is regulated by two independent signals. While the signal for induction of HXT gene expression is generated by Snf3 and Rgt2 glucose receptors, the repression signal requires the uptake and metabolism of glucose. In addition, the glucose induction of the HXT genes is required for repression of gene expression by glucose. Therefore the glucose repression defect of the snf3 rgt2 strain is indirect and is due to the lack of glucose uptake in this double mutant.
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Affiliation(s)
- Sabire Ozcan
- Department of Molecular and Cellular Biochemistry, Chandler Medical Center, University of Kentucky, Lexington, Kentucky 40536, USA.
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46
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Pritchard L, Kell DB. Schemes of flux control in a model of Saccharomyces cerevisiae glycolysis. EUROPEAN JOURNAL OF BIOCHEMISTRY 2002; 269:3894-904. [PMID: 12180966 DOI: 10.1046/j.1432-1033.2002.03055.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
We used parameter scanning to emulate changes to the limiting rate for steps in a fitted model of glucose-derepressed yeast glycolysis. Three flux-control regimes were observed, two of which were under the dominant control of hexose transport, in accordance with various experimental studies and other model predictions. A third control regime in which phosphofructokinase exerted dominant glycolytic flux control was also found, but it appeared to be physiologically unreachable by this model, and all realistically obtainable flux control regimes featured hexose transport as a step involving high flux control.
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47
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Ye L, Berden JA, van Dam K, Kruckeberg AL. Expression and activity of the Hxt7 high-affinity hexose transporter of Saccharomyces cerevisiae. Yeast 2001; 18:1257-67. [PMID: 11561293 DOI: 10.1002/yea.771] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
High-affinity hexose transport is required for efficient utilization of low hexose concentrations by the baker's yeast Saccharomyces cerevisiae. These low concentrations occur during the late exponential phase of batch growth on hexoses, during hexose-limited chemostat or fed-batch culture, or during growth on sugars such as sucrose and raffinose that are hydrolysed to hexoses outside the cell. The expression of the Hxt7 high-affinity glucose transporter of S. cerevisiae was examined during batch growth on glucose medium in a wild-type strain and a strain expressing only HXT7 (i.e. with null mutations in HXT1-HXT6). In the wild-type strain, HXT7 transcription was repressed at high glucose and was detected when the glucose in the culture approached depletion. In the HXT7-only strain, transcription of HXT7 was constitutive throughout the glucose growth phase and was increased further at low glucose concentrations. After glucose depletion, the levels of HXT7 mRNA declined rapidly in both strains. In contrast, the Hxt7 protein was relatively stable after glucose depletion. By monitoring the subcellular localization of an Hxt7::GFP fusion protein it was observed that Hxt7 was localized in the plasma membrane, even when expressed at high glucose concentrations in the HXT7-only strain. After glucose depletion Hxt7 was gradually endocytosed and targeted to the vacuole for degradation. The Hxt7::GFP fusion protein was a fully functional hexose transporter with a catalytic centre activity of approximately 200/sec. It is concluded that repression of HXT7 and degradation of Hxt7 at high glucose concentrations is dependent on a high glucose transport capacity.
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Affiliation(s)
- L Ye
- E.C. Slater Institute, The University of Amsterdam, Plantage Muidergracht 12, 1018 TV Amsterdam, The Netherlands
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48
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Milkowski C, Krampe S, Weirich J, Hasse V, Boles E, Breunig KD. Feedback regulation of glucose transporter gene transcription in Kluyveromyces lactis by glucose uptake. J Bacteriol 2001; 183:5223-9. [PMID: 11514503 PMCID: PMC95402 DOI: 10.1128/jb.183.18.5223-5229.2001] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2001] [Accepted: 06/29/2001] [Indexed: 11/20/2022] Open
Abstract
In the respirofermentative yeast Kluyveromyces lactis, only a single genetic locus encodes glucose transporters that can support fermentative growth. This locus is polymorphic in wild-type isolates carrying either KHT1 and KHT2, two tandemly arranged HXT-like genes, or RAG1, a low-affinity transporter gene that arose by recombination between KHT1 and KHT2. Here we show that KHT1 is a glucose-induced gene encoding a low-affinity transporter very similar to Rag1p. Kht2p has a lower K(m) (3.7 mM) and a more complex regulation. Transcription is high in the absence of glucose, further induced by low glucose concentrations, and repressed at higher glucose concentrations. The response of KHT1 and KHT2 gene regulation to high but not to low concentrations of glucose depends on glucose transport. The function of either Kht1p or Kht2p is sufficient to mediate the characteristic response to high glucose, which is impaired in a kht1 kht2 deletion mutant. Thus, the KHT genes are subject to mutual feedback regulation. Moreover, glucose repression of the endogenous beta-galactosidase (LAC4) promoter and glucose induction of pyruvate decarboxylase were abolished in the kht1 kht2 mutant. These phenotypes could be partially restored by HXT gene family members from Saccharomyces cerevisiae. The results indicate that the specific responses to high but not to low glucose concentrations require a high rate of glucose uptake.
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Affiliation(s)
- C Milkowski
- Institut für Genetik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany
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Betina S, Goffrini P, Ferrero I, Wésolowski-Louvel M. RAG4 gene encodes a glucose sensor in Kluyveromyces lactis. Genetics 2001; 158:541-8. [PMID: 11404320 PMCID: PMC1461679 DOI: 10.1093/genetics/158.2.541] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The rag4 mutant of Kluyveromyces lactis was previously isolated as a fermentation-deficient mutant, in which transcription of the major glucose transporter gene RAG1 was affected. The wild-type RAG4 was cloned by complementation of the rag4 mutation and found to encode a protein homologous to Snf3 and Rgt2 of Saccharomyces cerevisiae. These two proteins are thought to be sensors of low and high concentrations of glucose, respectively. Rag4, like Snf3 and Rgt2, is predicted to have the transmembrane structure of sugar transporter family proteins as well as a long C-terminal cytoplasmic tail possessing a characteristic 25-amino-acid sequence. Rag4 may therefore be expected to have a glucose-sensing function. However, the rag4 mutation was fully complemented by one copy of either SNF3 or RGT2. Since K. lactis appears to have no other genes of the SNF3/RGT2 type, we suggest that Rag4 of K. lactis may have a dual function of signaling high and low concentrations of glucose. In rag4 mutants, glucose repression of several inducible enzymes is abolished.
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Affiliation(s)
- S Betina
- Unité Microbiologie et Génétique, Université Claude Bernard, 43, Boulevard du 11 Novembre 1918, 69622 Villeurbanne Cédex, France
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Reijenga KA, Snoep JL, Diderich JA, van Verseveld HW, Westerhoff HV, Teusink B. Control of glycolytic dynamics by hexose transport in Saccharomyces cerevisiae. Biophys J 2001; 80:626-34. [PMID: 11159431 PMCID: PMC1301262 DOI: 10.1016/s0006-3495(01)76043-2] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
It is becoming accepted that steady-state fluxes are not necessarily controlled by single rate-limiting steps. This leaves open the issue whether cellular dynamics are controlled by single pacemaker enzymes, as has often been proposed. This paper shows that yeast sugar transport has substantial but not complete control of the frequency of glycolytic oscillations. Addition of maltose, a competitive inhibitor of glucose transport, reduced both average glucose consumption flux and frequency of glycolytic oscillations. Assuming a single kinetic component and a symmetrical carrier, a frequency control coefficient of between 0.4 and 0.6 and an average-flux control coefficient of between 0.6 and 0.9 were calculated for hexose transport activity. In a second approach, mannose was used as the carbon and free-energy source, and the dependencies on the extracellular mannose concentration of the transport activity, of the frequency of oscillations, and of the average flux were compared. In this case the frequency control coefficient and the average-flux control coefficient of hexose transport activity amounted to 0.7 and 0.9, respectively. From these results, we conclude that 1) transport is highly important for the dynamics of glycolysis, 2) most but not all control resides in glucose transport, and 3) there should at least be one step other than transport with substantial control.
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Affiliation(s)
- K A Reijenga
- Department of Molecular Cell Physiology, BioCentrum Amsterdam, Faculty of Biology, Vrije Universiteit, NL-1081 HV Amsterdam, The Netherlands
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