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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] [What about the content of this article? (0)] [Affiliation(s)] [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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Xu B, Hrmova M, Gilliham M. High affinity Na + transport by wheat HKT1;5 is blocked by K . Plant Direct 2020; 4:e00275. [PMID: 33103046 PMCID: PMC7576878 DOI: 10.1002/pld3.275] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 09/21/2020] [Indexed: 05/11/2023]
Abstract
The wheat sodium transporters TmHKT1;5-A and TaHKT1;5-D are encoded by genes underlying the major shoot Na+ exclusion loci Nax2 and Kna1 from Triticum monococcum (Tm) and Triticum aestivum (Ta), respectively. In contrast to HKT2 transporters that have been shown to exhibit high affinity K+-dependent Na+ transport, HKT1 proteins have, with one exception, only been shown to catalyze low affinity Na+ transport and no K+ transport. Here, using heterologous expression in Xenopus laevis oocytes we uncover a novel property of HKT1 proteins, that both TmHKT1;5-A and TaHKT1;5-D encode dual (high and low) affinity Na+-transporters with the high-affinity component being abolished when external K+ is in excess of external Na+. Three-dimensional structural modeling suggested that, compared to Na+, K+ is bound more tightly in the selectivity filter region by means of additional van der Waals forces, which is likely to explain the K+ block at the molecular level. The low-affinity component for Na+ transport of TmHKT1;5-A had a lower K m than that of TaHKT1;5-D and was less sensitive to external K+. We propose that these properties contribute towards the improvements in shoot Na+-exclusion and crop plant salt tolerance following the introgression of TmHKT1;5-A into diverse wheat backgrounds.
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Affiliation(s)
- Bo Xu
- Australian Research Council Centre of Excellence in Plant Energy BiologyUniversity of AdelaideWaite Research PrecinctGlen OsmondSAAustralia
- School of Agriculture, Food and Wine, and Waite Research InstituteUniversity of AdelaideWaite Research PrecinctGlen OsmondSAAustralia
| | - Maria Hrmova
- School of Agriculture, Food and Wine, and Waite Research InstituteUniversity of AdelaideWaite Research PrecinctGlen OsmondSAAustralia
- School of Life ScienceHuaiyin Normal UniversityHuai’anChina
| | - Matthew Gilliham
- Australian Research Council Centre of Excellence in Plant Energy BiologyUniversity of AdelaideWaite Research PrecinctGlen OsmondSAAustralia
- School of Agriculture, Food and Wine, and Waite Research InstituteUniversity of AdelaideWaite Research PrecinctGlen OsmondSAAustralia
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