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Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae

Mal11 catalyzes proton-coupled maltose transport across the plasma membrane of Saccharomyces cerevisiae. We used structure-based design of mutants and a kinetic analysis of maltose transport to determine the energy coupling mechanism of transport. We find that wildtype Mal11 is extremely well couple...

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Autores principales: Henderson, Ryan, Poolman, Bert
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Nature Publishing Group UK 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5662749/
https://www.ncbi.nlm.nih.gov/pubmed/29084970
http://dx.doi.org/10.1038/s41598-017-14438-1
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author Henderson, Ryan
Poolman, Bert
author_facet Henderson, Ryan
Poolman, Bert
author_sort Henderson, Ryan
collection PubMed
description Mal11 catalyzes proton-coupled maltose transport across the plasma membrane of Saccharomyces cerevisiae. We used structure-based design of mutants and a kinetic analysis of maltose transport to determine the energy coupling mechanism of transport. We find that wildtype Mal11 is extremely well coupled and allows yeast to rapidly accumulate maltose to dangerous levels, resulting under some conditions in self-lysis. Three protonatable residues lining the central membrane-embedded cavity of Mal11 were identified as having potential roles in proton translocation. We probed the mechanistic basis for proton coupling with uphill and downhill transport assays and found that single mutants can still accumulate maltose but with a lower coupling efficiency than the wildtype. Next, we combined the individual mutations and created double and triple mutants. We found some redundancy in the functions of the acidic residues in proton coupling and that no single residue is most critical for proton coupling to maltose uptake, unlike what is usually observed in related transporters. Importantly, the triple mutants were completely uncoupled but still fully active in downhill efflux and equilibrium exchange. Together, these results depict a concerted mechanism of proton transport in Mal11 involving multiple charged residues.
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spelling pubmed-56627492017-11-08 Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae Henderson, Ryan Poolman, Bert Sci Rep Article Mal11 catalyzes proton-coupled maltose transport across the plasma membrane of Saccharomyces cerevisiae. We used structure-based design of mutants and a kinetic analysis of maltose transport to determine the energy coupling mechanism of transport. We find that wildtype Mal11 is extremely well coupled and allows yeast to rapidly accumulate maltose to dangerous levels, resulting under some conditions in self-lysis. Three protonatable residues lining the central membrane-embedded cavity of Mal11 were identified as having potential roles in proton translocation. We probed the mechanistic basis for proton coupling with uphill and downhill transport assays and found that single mutants can still accumulate maltose but with a lower coupling efficiency than the wildtype. Next, we combined the individual mutations and created double and triple mutants. We found some redundancy in the functions of the acidic residues in proton coupling and that no single residue is most critical for proton coupling to maltose uptake, unlike what is usually observed in related transporters. Importantly, the triple mutants were completely uncoupled but still fully active in downhill efflux and equilibrium exchange. Together, these results depict a concerted mechanism of proton transport in Mal11 involving multiple charged residues. Nature Publishing Group UK 2017-10-30 /pmc/articles/PMC5662749/ /pubmed/29084970 http://dx.doi.org/10.1038/s41598-017-14438-1 Text en © The Author(s) 2017 Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.
spellingShingle Article
Henderson, Ryan
Poolman, Bert
Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae
title Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae
title_full Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae
title_fullStr Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae
title_full_unstemmed Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae
title_short Proton-solute coupling mechanism of the maltose transporter from Saccharomyces cerevisiae
title_sort proton-solute coupling mechanism of the maltose transporter from saccharomyces cerevisiae
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5662749/
https://www.ncbi.nlm.nih.gov/pubmed/29084970
http://dx.doi.org/10.1038/s41598-017-14438-1
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