Involvement of endocytosis in catabolite inactivation of the K+ and glucose transport systems in Saccharomyces cerevisiae

Riballo, Enriqueta

doi:10.1016/0378-1097(94)90148-1

Cited by 13 publications

(16 citation statements)

References 13 publications

(22 reference statements)

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“…Most likely this is also the main route of degradation of plasma membrane proteins in S. cerevisiae. This is underlined by the observations that, in addition to that of the maltose transporter, degradation of aand ␣-factor receptors (8, 41), uracil permease (44), and inositol permease (24) occurs in the vacuole after endocytosis and also that catabolite inactivation of the K ϩ and glucose transporters is preceded by endocytosis (33). In addition to vacuolar proteolysis, other pathways may also contribute to degradation of plasma membrane proteins, but little is known about this possibility (13).…”

Section: Resultsmentioning

confidence: 99%

Catabolite inactivation of the yeast maltose transporter occurs in the vacuole after internalization by endocytosis

et al. 1995

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The maltose transporter of Saccharomyces cerevisiae is rapidly degraded during fermentation in the absence of a nitrogen source. The location and mechanism of degradation of the transporter have been investigated. Using mutants defective in endocytosis, we have shown that degradation of this transporter requires internalization by endocytosis. In addition, studies of mutants defective in proteasome or vacuolar proteolysis revealed that degradation occurs in the vacuole and is independent of proteasome function. The results also revealed that degradation of the maltose transporter requires Sec18p and raised the question of whether in the absence of Sec18p activity the internalized maltose transporter is recycled back to the plasma membrane.Sugar transporters are integral plasma membrane proteins that catalyze the first rate-limiting step of glycolysis in Saccharomyces cerevisiae (11). Several strategies are used by this organism to adjust the activities of these proteins to different environmental conditions (22). One of these strategies is the irreversible inactivation of the transporters, which occurs when protein synthesis is impaired upon exhaustion of a nitrogen source in the medium (3-5, 9, 23, 27) and which results in dramatic physiological effects (20,21,23). This inactivation, known as catabolite inactivation (17), affects mainly the V max of the transporters, follows first-order kinetics, and is an energy-dependent process stimulated by fermentable substrates (3,4,9). By using polyclonal antibodies against a recombinant maltose transporter protein, it has been shown that catabolite inactivation is due to proteolysis (26). The experiments reported here attempt to establish the location and mechanism of the maltose transporter degradation. We investigated the inactivation of the maltose transporter by measuring the rate of maltose uptake with radioactive sugar as well as by determining the cellular content of the transporter with polyclonal antibodies. Possible loci investigated are the plasma membrane, which is the locus of transporter action, the cytoplasm, and the vacuole after internalization of the transporter by endocytosis. In this study, we used strains defective in the internalization step of endocytosis as well as strains that show a defect either in the ''chymotrypsin-like'' activity of the proteasome complex or in the two main vacuolar endopeptidases.

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Section: Resultsmentioning

confidence: 99%

Catabolite inactivation of the yeast maltose transporter occurs in the vacuole after internalization by endocytosis

et al. 1995

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“…However, under field conditions, yeast cells spend most of their time not in logarithmic growth but in the stationary phase, starving for one or several nutrients (54,55). Under these conditions, mating, which allows sporulation (30), and turnover of plasma membrane proteins, which allows adaptation to new nutrients (15,18,20,31,40,41,53), could be critical for survival and effective competition with other organisms. Therefore, trehalose accumulated during nutrient starvation in yeast cells could be essential for the occurrence of endocytosis and its related functions, i.e., mating and plasma membrane turnover, when these two functions are required and high concentrations of ethanol are present in the medium.…”

Section: Discussionmentioning

confidence: 99%

“…In animal cells, endocytosis is involved in functions such as nutrition, hormone response, immune defense, and membrane conservation. In yeast cells, endocytosis is involved in mating, which is initiated by binding and internalization of the secreted a-and ␣-factors to receptors located on the plasma membrane (for a review, see reference 30), and the reconstruction of the plasma membrane, which is initiated by changes in nutritional conditions that trigger internalization and degradation of plasma membrane proteins, usually unneeded nutrient transporters (15,18,20,31,40,41,53). As both functions are important for yeast survival, endocytosis is probably an important process in yeast and, therefore, this organism should have developed some means to circumvent the inhibition of endocytosis by ethanol.…”

mentioning

confidence: 99%

Internal Trehalose Protects Endocytosis from Inhibition by Ethanol inSaccharomyces cerevisiae

Lucero

Peñalver

Moreno

et al. 2000

Appl Environ Microbiol

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Endocytosis in Saccharomyces cerevisiae is inhibited by concentrations of ethanol of 2 to 6% (vol/vol), which are lower than concentrations commonly present in its natural habitats. In spite of this inhibition, endocytosis takes place under enological conditions when high concentrations of ethanol are present. Therefore, it seems that yeast has developed some means to circumvent the inhibition. In this work we have investigated this possibility. We identified two stress conditions under which endocytosis was resistant to inhibition by ethanol: fermentation during nitrogen starvation and growth on nonfermentable substrates. Under these conditions, yeast accumulates stress protectors, primarily trehalose and Hsp104, a protein required for yeast to survive ethanol stress. We found the following.

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“…Likewise, catabolite inactivation of Gal2p also occurs after ubiquitination by its degradation in the vacuole [28, 113]. Endocytosis seems also to be involved in catabolite inactivation of the glucose transport system [27]. Contradictory results have been presented concerning the involvement of cAMP‐dependent protein kinase in catabolite inactivation [115, 116].…”

Section: Additional Regulatory Aspects Of Hexose Uptakementioning

confidence: 99%

The molecular genetics of hexose transport in yeasts

1997

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Transport across the plasma membrane is the first, obligatory step of hexose utilization. In yeast cells the uptake of hexoses is mediated by a large family of related transporter proteins. In baker's yeast Saccharomyces cerevisiae the genes of 20 different hexose transporter-related proteins have been identified. Six of these transmembrane proteins mediate the metabolically relevant uptake of glucose, fructose and mannose for growth, two others catalyze the transport of only small amounts of these sugars, one protein is a galactose transporter but also able to transport glucose, two transporters act as glucose sensors, two others are involved in the pleiotropic drug resistance process, and the functions of the remaining hexose transporter-related proteins are not yet known. The catabolic hexose transporters exhibit different affinities for their substrates, and expression of their corresponding genes is controlled by the glucose sensors according to the availability of carbon sources. In contrast, milk yeast Kluyveromyces lactis contains only a few different hexose transporters. Genes of other monosaccharide transporter-related proteins have been found in fission yeast Schizosaccharomyces pombe and in the xylose-fermenting yeast Pichia stipitis. However, the molecular genetics of hexose transport in many other yeasts remains to be established. The further characterization of this multigene family of hexose transporters should help to elucidate the role of transport in yeast sugar metabolism.

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Involvement of endocytosis in catabolite inactivation of the K+ and glucose transport systems in Saccharomyces cerevisiae

Cited by 13 publications

References 13 publications

Catabolite inactivation of the yeast maltose transporter occurs in the vacuole after internalization by endocytosis

Catabolite inactivation of the yeast maltose transporter occurs in the vacuole after internalization by endocytosis

Internal Trehalose Protects Endocytosis from Inhibition by Ethanol inSaccharomyces cerevisiae

The molecular genetics of hexose transport in yeasts

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