title: The transport of carboxylic acids and important role of the Jen1p transporter during the development of yeast colonies.
abstract: On solid substrates, yeast colonies pass through distinct developmental phases characterized by the changes in pH of their surroundings from acidic to nearly alkaline and vice versa. At the beginning of the alkali phase colonies start to produce ammonia, which functions as a quorum-sensing molecule inducing the reprogramming of cell metabolism. Such reprogramming includes, among others, the activation of several plasma membrane transporters and is connected with colony differentiation. In the present study, we show that colony cells can use two transport mechanisms to import lactic acid: a 'saturable' component of the transport, which requires the presence of a functional Jen1p transporter, and a 'non-saturable' component (diffusion) that is independent of Jen1p. During colony development, the efficiency of both transport components changes similarly in central and outer colonial cells. Although the lactate uptake capacity of central cells gradually decreases during colony development, the lactate uptake capacity of outer cells peaks during the alkali phase and is also kept relatively high in the second acidic phase. This lactate uptake profile correlates with the localization of the Jen1p transporter to the plasma membrane of colony cells. Both lactic acid uptake mechanisms are diminished in sok2 colonies where JEN1 expression is decreased. The Sok2p transcription factor may therefore be involved in the regulation of non-saturable lactic acid uptake in yeast colonies.
authors.affiliation: Molecular and Environmental Biology Centre (CBMA), Department of Biology, Campus de Gualtar, University of Minho, 4710-057 Braga, Portugal.
authors.forename: Sandra
authors.initials: S
authors.lastname: Paiva
authors.forename: Dita
authors.initials: D
authors.lastname: Strachotová
authors.forename: Helena
authors.initials: H
authors.lastname: Kučerová
authors.forename: Otakar
authors.initials: O
authors.lastname: Hlaváček
authors.forename: Sandra
authors.initials: S
authors.lastname: Mota
authors.forename: Margarida
authors.initials: M
authors.lastname: Casal
authors.forename: Zdena
authors.initials: Z
authors.lastname: Palková
authors.forename: Libuše
authors.initials: L
authors.lastname: Váchová
mesh_terms: D000641:Ammonia / Q000378:metabolism; D001693:Biological Transport, Active; D002264:Carboxylic Acids / Q000378:metabolism; D004058:Diffusion; D055786:Gene Knockout Techniques; D019344:Lactic Acid / Q000378:metabolism*; D027501:Monocarboxylic Acid Transporters / Q000502:physiology*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000254:growth & development / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D015398:Signal Transduction; D027981:Symporters / Q000502:physiology*
chemical_list: D002264:Carboxylic Acids; C118697:JEN1 protein, S cerevisiae; D027501:Monocarboxylic Acid Transporters; D012097:Repressor Proteins; C097076:SOK2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D027981:Symporters; D019344:Lactic Acid; D000641:Ammonia