Faculty Opinions recommendation of A conserved GTPase-containing complex is required for intracellular sorting of the general amino-acid permease in yeast.

2006 ◽  
Author(s):  
Ruth Collins
Keyword(s):  
Amino Acid ◽  
Amino Acid Permease ◽  
General Amino Acid Permease ◽  
Intracellular Sorting

scholarly journals Amino Acids Regulate Retrieval of the Yeast General Amino Acid Permease from the Vacuolar Targeting Pathway

2006 ◽  
Vol 17 (7) ◽  
pp. 3031-3050 ◽  
Author(s):  
Marta Rubio-Texeira ◽  
Chris A. Kaiser
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Amino Acid ◽  
Membrane Trafficking ◽  
Amino Acid Permease ◽  
A Genome ◽  
High Amino Acid ◽  
General Amino Acid Permease ◽  
Intracellular Sorting ◽  
Amino Acid Concentrations

Intracellular sorting of the general amino acid permease (Gap1p) in Saccharomyces cerevisiae depends on availability of amino acids such that at low amino acid concentrations Gap1p is sorted to the plasma membrane, whereas at high concentrations Gap1p is sorted to the vacuole. In a genome-wide screen for mutations that affect Gap1p sorting we identified deletions in a subset of components of the ESCRT (endosomal sorting complex required for transport) complex, which is required for formation of the multivesicular endosome (MVE). Gap1p-GFP is delivered to the vacuolar interior by the MVE pathway in wild-type cells, but when formation of the MVE is blocked by mutation, Gap1p-GFP efficiently cycles from this compartment to the plasma membrane, resulting in unusually high permease activity at the cell surface. Importantly, cycling of Gap1p-GFP to the plasma membrane is blocked by high amino acid concentrations, defining recycling from the endosome as a major step in Gap1p trafficking under physiological control. Mutations in LST4 and LST7 genes, previously identified for their role in Gap1p sorting, similarly block MVE to plasma membrane trafficking of Gap1p. However, mutations in other recycling complexes such as the retromer had no significant effect on the intracellular sorting of Gap1p, suggesting that Gap1p follows a genetically distinct pathway for recycling. We previously found that Gap1p sorting from the Golgi to the endosome requires ubiquitination of Gap1p by an Rsp5p ubiquitin ligase complex, but amino acid abundance does not appear to significantly alter the accumulation of polyubiquitinated Gap1p. Thus the role of ubiquitination appears to be a signal for delivery of Gap1p to the MVE, whereas amino acid abundance appears to control the cycling of Gap1p from the MVE to the plasma membrane.

scholarly journals Transport activity–dependent intracellular sorting of the yeast general amino acid permease

2011 ◽  
Vol 22 (11) ◽  
pp. 1919-1929 ◽  
Author(s):  
Natalie E. Cain ◽  
Chris A. Kaiser
Keyword(s):  
Amino Acids ◽  
Plasma Membrane ◽  
Amino Acid ◽  
Regulatory Mechanism ◽  
Transport Activity ◽  
Amino Acid Permease ◽  
Amino Acid Mixtures ◽  
General Amino Acid Permease ◽  
Intracellular Sorting ◽  
Activity Dependent

Intracellular trafficking of the general amino acid permease, Gap1p, of Saccharomyces cerevisiae is regulated by amino acid abundance. When amino acids are scarce Gap1p is sorted to the plasma membrane, whereas when amino acids are abundant Gap1p is sorted from the trans-Golgi through the multivesicular endosome (MVE) and to the vacuole. Here we test the hypothesis that Gap1p itself is the sensor of amino acid abundance by examining the trafficking of Gap1p mutants with altered substrate specificity and transport activity. We show that trafficking of mutant Gap1pA297V, which does not transport basic amino acids, is also not regulated by these amino acids. Furthermore, we have identified a catalytically inactive mutant that does not respond to complex amino acid mixtures and constitutively sorts Gap1p to the plasma membrane. Previously we showed that amino acids govern the propensity of Gap1p to recycle from the MVE to the plasma membrane. Here we propose that in the presence of substrate the steady-state conformation of Gap1p shifts to a state that is unable to be recycled from the MVE. These results indicate a parsimonious regulatory mechanism by which Gap1p senses its transport substrates to set an appropriate level of transporter activity at the cell surface.

Ammonia regulation of amino acid permeases in Saccharomyces cerevisiae

1983 ◽  
Vol 3 (4) ◽  
pp. 672-683
Author(s):  
W E Courchesne ◽  
B Magasanik
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Amino Acid ◽  
Cytoplasmic Membrane ◽  
Nitrogen Sources ◽  
Amino Acid Permease ◽  
Inducer Exclusion ◽  
Amino Acid Permeases ◽  
General Amino Acid Permease ◽  
State Growth ◽  
And Control

The activities of the proline-specific permease (PUT4) and the general amino acid permease (GAP1) of Saccharomyces cerevisiae vary 70- to 140-fold in response to the nitrogen source of the growth medium. The PUT4 and GAP1 permease activities are regulated by control of synthesis and control of activity. These permeases are irreversibly inactivated by addition of ammonia or glutamine, lowering the activity to that found during steady-state growth on these nitrogen sources. Mutants altered in the regulation of the PUT4 permease (Per-) have been isolated. The mutations in these strains are pleiotropic and affect many other permeases, but have no direct effect on various cytoplasmic enzymes involved in nitrogen assimilation. In strains having one class of mutations (per1), ammonia inactivation of the PUT4 and GAP1 permeases did not occur, whereas glutamate and glutamine inactivation did. Thus, there appear to be two independent inactivation systems, one responding to ammonia and one responding to glutamate (or a metabolite of glutamate). The mutations were found to be nuclear and recessive. The inactivation systems are constitutive and do not require transport of the effector molecules per se, apparently operating on the inside of the cytoplasmic membrane. The ammonia inactivation was found not to require a functional glutamate dehydrogenase (NADP). These mutants were used to show that ammonia exerts control of arginase synthesis largely by inducer exclusion. This may be the primary mode of nitrogen regulation for most nitrogen-regulated enzymes of S. cerevisiae.

scholarly journals Rhizobium leguminosarum Has a Second General Amino Acid Permease with Unusually Broad Substrate Specificity and High Similarity to Branched-Chain Amino Acid Transporters (Bra/LIV) of the ABC Family

2002 ◽  
Vol 184 (15) ◽  
pp. 4071-4080 ◽  
Author(s):  
A. H. F. Hosie ◽  
D. Allaway ◽  
C. S. Galloway ◽  
H. A. Dunsby ◽  
P. S. Poole
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Rhizobium Leguminosarum ◽  
Binding Protein ◽  
Amino Acid Transporters ◽  
Acid Uptake ◽  
Amino Acid Permease ◽  
Branched Chain Amino Acid ◽  
General Amino Acid Permease ◽  
Branched Chain

ABSTRACT Amino acid uptake by Rhizobium leguminosarum is dominated by two ABC transporters, the general amino acid permease (Aap) and the branched-chain amino acid permease (BraRl). Characterization of the solute specificity of BraRl shows it to be the second general amino acid permease of R. leguminosarum. Although BraRl has high sequence identity to members of the family of hydrophobic amino acid transporters (HAAT), it transports a broad range of solutes, including acidic and basic polar amino acids (l-glutamate, l-arginine, and l-histidine), in addition to neutral amino acids (l-alanine and l-leucine). While amino and carboxyl groups are required for transport, solutes do not have to be α-amino acids. Consistent with this, BraRl is the first ABC transporter to be shown to transport γ-aminobutyric acid (GABA). All previously identified bacterial GABA transporters are secondary carriers of the amino acid-polyamine-organocation (APC) superfamily. Also, transport by BraRl does not appear to be stereospecific as d amino acids cause significant inhibition of uptake of l-glutamate and l-leucine. Unlike all other solutes tested, l-alanine uptake is not dependent on solute binding protein BraCRl. Therefore, a second, unidentified solute binding protein may interact with the BraDEFGRl membrane complex during l-alanine uptake. Overall, the data indicate that BraRl is a general amino acid permease of the HAAT family. Furthermore, BraRl has the broadest solute specificity of any characterized bacterial amino acid transporter.

N-Acetylglucosamine-inducible CaGAP1 encodes a general amino acid permease which co-ordinates external nitrogen source response and morphogenesis in Candida albicans

Microbiology ◽  
2003 ◽  
Vol 149 (9) ◽  
pp. 2597-2608 ◽  
Author(s):  
Subhrajit Biswas ◽  
Monideepa Roy ◽  
Asis Datta
Keyword(s):  
Amino Acids ◽  
Candida Albicans ◽  
Amino Acid ◽  
Genomic Library ◽  
Northern Analysis ◽  
Dependent Manner ◽  
Amino Acid Permease ◽  
Environmental Signals ◽  
General Amino Acid Permease ◽  
Hyphal Formation

Candida albicans is able to grow in a variety of reversible morphological forms (yeast, pseudohyphal and hyphal) in response to various environmental signals, noteworthy among them being N-acetylglucosamine (GlcNAc). The gene CaGAP1, homologous to GAP1, which encodes the general amino acid permease from Saccharomyces cerevisiae, was isolated on the basis of its induction by GlcNAc through differential screening of a C. albicans genomic library. The gene could functionally complement an S. cerevisiae gap1 mutant by rendering it susceptible to the toxic amino acid analogue mimosine in minimal proline media. As in S. cerevisiae, mutation of the CaGAP1 gene had an effect on citrulline uptake in C. albicans. Northern analysis showed that GlcNAc-induced expression of CaGAP1 was further enhanced in synthetic minimal media supplemented with single amino acids (glutamate, proline and glutamine) or urea (without amino acids) but repressed in minimal ammonium media. Induction of CaGAP1 expression by GlcNAc was nullified in C. albicans deleted for the transcription factor CPH1 and the hyphal regulator RAS1, indicating the involvement of Cph1p-dependent Ras1p signalling in CaGAP1 expression. A homozygous mutant of this gene showed defective hyphal formation in solid hyphal-inducing media and exhibited less hyphal clumps when induced by GlcNAc. Alteration of morphology and short filamentation under nitrogen-starvation conditions in the heterozygous mutant suggested that CaGAP1 affects morphogenesis in a dose-dependent manner.

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