scholarly journals Extracellular loops matter – subcellular location and function of the lysine transporter Lyp1 from Saccharomyces cerevisiae

FEBS Journal ◽  
2020 ◽  
Vol 287 (20) ◽  
pp. 4401-4414 ◽  
Author(s):  
Joury S. van‘t Klooster ◽  
Frans Bianchi ◽  
Ruben B. Doorn ◽  
Mirco Lorenzon ◽  
Jarnick H. Lusseveld ◽  
...  
Genetics ◽  
1998 ◽  
Vol 150 (2) ◽  
pp. 553-562
Author(s):  
Margaret I Kanipes ◽  
John E Hill ◽  
Susan A Henry

Abstract The isolation of mutants of Schizosaccharomyces pombe defective in the synthesis of phosphatidylcholine via the methylation of phosphatidylethanolamine is reported. These mutants are choline auxotrophs and fall into two unlinked complementation groups, cho1 and cho2. We also report the analysis of the cho1+ gene, the first structural gene encoding a phospholipid biosynthetic enzyme from S. pombe to be cloned and characterized. The cho1+ gene disruption mutant (cho1Δ) is viable if choline is supplied and resembles the cho1 mutants isolated after mutagenesis. Sequence analysis of the cho1+ gene indicates that it encodes a protein closely related to phospholipid methyltransferases from Saccharomyces cerevisiae and rat. Phospholipid methyltransferases encoded by a rat liver cDNA and the S. cerevisiae OPI3 gene are both able to complement the choline auxotrophy of the S. pombe cho1 mutants. These results suggest that both the structure and function of the phospholipid N-methyltransferases are broadly conserved among eukaryotic organisms.


2000 ◽  
Vol 20 (21) ◽  
pp. 7893-7902 ◽  
Author(s):  
Matthew E. Portnoy ◽  
Xiu Fen Liu ◽  
Valeria Cizewski Culotta

ABSTRACT The baker's yeast Saccharomyces cerevisiae expresses three homologues of the Nramp family of metal transporters: Smf1p, Smf2p, and Smf3p, encoded by SMF1, SMF2, andSMF3, respectively. Here we report a comparative analysis of the yeast Smf proteins at the levels of localization, regulation, and function of the corresponding metal transporters. Smf1p and Smf2p function in cellular accumulation of manganese, and the two proteins are coregulated by manganese ions and the BSD2 gene product. Under manganese-replete conditions, Bsd2p facilitates trafficking of Smf1p and Smf2p to the vacuole, where these transport proteins are degraded. However, Smf1p and Smf2p localize to distinct cellular compartments under metal starvation: Smf1p accumulates at the cell surface, while Smf2p is restricted to intracellular vesicles. The third Nramp homologue, Smf3p, is quite distinctive. Smf3p is not regulated by Bsd2p or by manganese ions and is not degraded in the vacuole. Instead, Smf3p is down-regulated by iron through a mechanism that does not involve transcription or protein stability. Smf3p localizes to the vacuolar membrane independently of metal treatment, and yeast cells lacking Smf3p show symptoms of iron starvation. We propose that Smf3p helps to mobilize vacuolar stores of iron.


2001 ◽  
Vol 183 (1) ◽  
pp. 46-54 ◽  
Author(s):  
Yvonne Weber ◽  
Uwe J. Santore ◽  
Joachim F. Ernst ◽  
Rolf K. Swoboda

ABSTRACT Sec20p is a component of the yeast Saccharomyces cerevisiae secretory pathway that does not have a close homolog in higher eukaryotic cells. To verify the function of Sec20p in other fungal species, we characterized the gene encoding a Sec20p homolog in the human fungal pathogen Candida albicans. The deduced protein has 27% identity with, but is missing about 100 N-terminal residues compared to S. cerevisiae Sec20p, which is part of the cytoplasmic tail interacting with the cytoplasmic protein Tip20p. Because a strain lacking both C. albicans SEC20alleles could not be constructed, we placed SEC20 under transcriptional control of two regulatable promoters, MET3pand PCK1p. Repression of SEC20 expression in these strains prevented (MET3p-SEC20 allele) or retarded (PCK1p-SEC20 allele) growth and led to the appearance of extensive intracellular membranes, which frequently formed stacks. Reduced SEC20 expression in the PCK1p-SEC20strain did not affect morphogenesis but led to a series of hypersensitivity phenotypes including supersensitivity to aminoglycoside antibiotics, to nystatin, to sodium dodecyl sulfate, and to cell wall inhibitors. These results demonstrate the occurrence and function of Sec20p in a fungal species other than S. cerevisiae, but the lack of the N-terminal domain and the apparent absence of a close TIP20 homolog in the C. albicans genome also indicate a considerable diversity in mechanisms of retrograde vesicle traffic in eukaryotes.


2019 ◽  
Vol 30 (12) ◽  
pp. 1555-1574 ◽  
Author(s):  
Maria Nieves Martinez Marshall ◽  
Anita Emmerstorfer-Augustin ◽  
Kristin L. Leskoske ◽  
Lydia H. Zhang ◽  
Biyun Li ◽  
...  

Eukaryotic cell survival requires maintenance of plasma membrane (PM) homeostasis in response to environmental insults and changes in lipid metabolism. In yeast, a key regulator of PM homeostasis is target of rapamycin (TOR) complex 2 (TORC2), a multiprotein complex containing the evolutionarily conserved TOR protein kinase isoform Tor2. PM localization is essential for TORC2 function. One core TORC2 subunit (Avo1) and two TORC2-­associated regulators (Slm1 and Slm2) contain pleckstrin homology (PH) domains that exhibit specificity for binding phosphatidylinositol-4,5- bisphosphate (PtdIns4,5P2). To investigate the roles of PtdIns4,5P2 and constituent subunits of TORC2, we used auxin-inducible degradation to systematically eliminate these factors and then examined localization, association, and function of the remaining TORC2 components. We found that PtdIns4,5P2 depletion significantly reduced TORC2 activity, yet did not prevent PM localization or cause disassembly of TORC2. Moreover, truncated Avo1 (lacking its C-terminal PH domain) was still recruited to the PM and supported growth. Even when all three PH-containing proteins were absent, the remaining TORC2 subunits were PM-bound. Revealingly, Avo3 localized to the PM independent of both Avo1 and Tor2, whereas both Tor2 and Avo1 required Avo3 for their PM anchoring. Our findings provide new mechanistic information about TORC2 and pinpoint Avo3 as pivotal for TORC2 PM localization and assembly in vivo.


1974 ◽  
Vol 139 (3) ◽  
pp. 535-545 ◽  
Author(s):  
G. B. Fincher ◽  
W. H. Sawyer ◽  
B. A. Stone

1. An arabinogalactan-peptide from wheat endosperm was studied by using physicochemical techniques and some aspects of its chemical structure were determined. 2. The arabinogalactan-peptide is a non-associating, polydisperse macromolecule ([unk]=22000) which exhibits only minor non-ideal effects in aqueous solution. 3. Examination of the products of partial acid hydrolysis of the polysaccharide component showed that arabinose is present in the α-l-arabinofuranosyl configuration, and i.r.-absorption spectroscopy and optical-rotation studies suggest that the d-galactopyranose residues are linked by glycosidic linkages in the β-anomeric configuration. 4. The arabinogalactan is linked to a peptide which represents 8% (w/w) of the arabinogalactan-peptide and which may be present as a molecular core. Partial degradation of the polymer by successive treatment with oxalic acid and NaOH showed that the linkage between polysaccharide and peptide involves galactose and hydroxyproline residues and is glycosidic in nature. A tentative model is proposed for the structure of the wheat endosperm arabinogalactan-peptide. 5. The subcellular location and function of the arabinogalactan-peptide is discussed in relation to previous work with related molecules.


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