<i>Schizosaccharomyces pombe isp4</i> encodes a transporter representing a novel family of oligopeptide transporters

Lubkowitz, Mark; Barnes, David J.; Breslav, Michael; Burchfield, Aaron; Naider, Fred; Becker, Jeffrey M.

doi:10.1046/j.1365-2958.1998.00827.x

Cited by 81 publications

(95 citation statements)

References 47 publications

(78 reference statements)

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“…3B). As reported previously by Lubkowitz et al (1998), none of the OPT family members showed any significant sequence similarity to the known ABC or PTR peptide transporters (data not shown).…”

Section: Molecular Characterization Of Osopt10 Proteinsupporting

confidence: 82%

“…In contrast to PTR peptide transporters, the yeast OPT transporters predominantly recognize tetra-and pentapeptides (Lubkowitz et al 1997;Lubkowitz et al 1998), including the endogenous opioids Met-enkephalin (YG GFM) and Leu-enkephalin (YGGFL) (Hauser et al 2000). Database searches for homology with the C. albicans CaOpt1p revealed nine putative Arabidopsis OPT orthologs that form a distinct subfamily compared with the fungal OPTs Stacey et al 2002).…”

Section: Introductionmentioning

confidence: 99%

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Expression analysis and characterization of rice oligopeptide transport gene (OsOPT10) that contributes to salt stress tolerance

Jung¹,

Lee²,

Han³

et al. 2010

Journal of Plant Biotechnology

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Knock-out of a gene by insertional mutagenesis is a direct way to address its function through the mutant phenotype. Among ca. 15,000 gene-trapped Ds insertion lines of rice, we identified one line from selected sensitive lines in highly salt stress. We conducted gene tagging by TAIL-PCR, and DNA gel blot analysis from salt sensitive mutant. A gene encoding an oligopeptide transporter (OPT family) homologue was disrupted by the insertion of a Ds transposon into the OsOPT10 gene that was located shot arm of chromosome 8. The OsOPT10 gene (NP_ 001062118.) has 6 exons and encodes a protein (752 aa) containing the OPT family domain. RT-PCR analysis showed that the expression of OsOPT10 gene was rapidly and strongly induced by stresses such as high-salinity (250 mM), osmotic, drought, 100 µM ABA. The subcellular localization assay indicated that OsOPT10 was localized specifically in the plasma membrane. Overexpression of OsOPT10 in Arabidopsis thaliana and rice conferred tolerance of transgenic plants to salt stress. Further we found expression levels of some stress related genes were inhibited in OsOPT10 transgenic plants. These results suggested that OsOPT10 might play crucial but differential roles in plant responses to various abiotic stresses

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Section: Molecular Characterization Of Osopt10 Proteinsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 99%

Expression analysis and characterization of rice oligopeptide transport gene (OsOPT10) that contributes to salt stress tolerance

Jung¹,

Lee²,

Han³

et al. 2010

Journal of Plant Biotechnology

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“…It has been postulated that Arabidopsis homologues of YS1, the 8-member YSL (YS-like) family, may be involved in transporting NA-metal chelates within the plant (60). OPT and YSL are two divergent families of proteins (63) with homology to ISP4, a fungal oligopeptide transporter (64). Our yeast complementation experiments have shown that AtOPT3 can transport copper, manganese, and possibly iron as it was suggested by the transcriptional regulation pattern.…”

Section: Independent Systems Of Copper and Iron Homeostasis In Arabidmentioning

confidence: 60%

Expression Profiles of Arabidopsis thaliana in Mineral Deficiencies Reveal Novel Transporters Involved in Metal Homeostasis

Wintz

Fox

et al. 2003

Journal of Biological Chemistry

370

330

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Plants directly assimilate minerals from the environment and thus are key for acquisition of metals by all subsequent consumers. Limited bio-availability of copper, zinc and iron in soil decreases both the agronomic productivity and the nutrient quality of crops. Understanding the molecular mechanisms underlying metal homeostasis in plants is a prerequisite to optimizing plant yield and metal nutrient content. To absorb and maintain a balance of potentially toxic metal ions, plants utilize poorly understood mechanisms involving a large number of membrane transporters and metalbinding proteins with overlapping substrate specificities and complex regulation. To better understand the function and the integrated regulation, we analyzed in Arabidopsis the expression patterns in roots and in leaves of 53 genes coding for known or potential metal transporters, in response to copper, zinc, and iron deficiencies in Arabidopsis. Comparative analysis of gene expression profiles revealed specific transcriptional regulation by metals of the genes contrasting with the known wide substrate specificities of the encoded transporters. Our analysis suggested novel transport roles for several gene products and we used functional complementation of yeast mutants to correlate specific regulation by metals with transport activity. We demonstrate that two ZIP genes, ZIP2 and ZIP4, are involved in copper transport. We also present evidence that AtOPT3, a member of the oligopeptide transporter gene family with significant similarities to the maize iron-phytosiderophore transporter YS1, is regulated by metals and heterologous expression AtOPT3 can rescue yeast mutants deficient in metal transport.All organisms require metal prosthetic groups for their unique catalytic and structural properties. In proteins, copper and iron catalyze reduction-oxidation reactions, while zinc plays an essential structural or enzymatic role. Yet most metal ions are very reactive and can be toxic to cells when present in excess. Thus, it is important for organisms to maintain adequate levels of metals in tight homeostasis using complex and often evolutionarily conserved mechanisms for the uptake and transport of low solubility metals and storage of metal ions in a non-toxic form. Despite rapid progress in recent years of our understanding of metal homeostasis in yeast, (1) our knowledge of metal metabolism in plants is still rudimentary (2).A large number of cation transporters potentially involved in metal ion homeostasis have been identified on the genome of the model plant Arabidopsis thaliana (3). Several members of the 15 ZIP gene family (4) and of the 6 NRAMP family of transporters (3) have been characterized and shown to be involved in metal uptake and transport in plants (5-10). ABC transporters (11) and P-type ATPase pumps (12, 13) are also known to be involved in metal ions trafficking metals into organelles. Since metals are cytotoxic as free ions, they are chelated for both intracellular storage and long-distance transport. These chelators are eith...

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“…Furthermore, Gln-222 was found conserved among different OPT members, whereas Gln-526 was present only in Pgt1 but not in the other functionally characterized oligopeptide transporters. This differential pattern of conservation and effect of mutations of Gln-222 and Gln-526 becomes particularly remarkable as Pgt1, like Hgt1p, is the only other PT member characterized to transport glutathione with high affinity, whereas all the other three PT members, AtOpt4, CaOpt1, and Isp4, have been shown to transport tetrapeptides and pentapeptides but do not transport glutathione (4,7,35,36). Taken together, the results suggest that although both glutamine residues participate in substrate transport, Gln-526 is critical in identifying glutathione as substrate, whereas Gln-222 recognizes a structural feature common to oligopeptides, including glutathione, a modified tripeptide.…”

Section: Discussionmentioning

confidence: 99%

“…These include Pgt1, CaOpt1, Isp4, and AtOpt4. Pgt1 has been recently characterized as a high affinity glutathione transporter from Schizosaccharomyces pombe (4), whereas AtOpt4 from Arabidopsis thaliana, CaOpt1 from Candida albicans, and Isp4 from S. pombe have been shown to specifically mediate uptake of oligopeptides (7,35,36).…”

Section: Conservation Pattern Of Residues Important For Hgt1p Functiomentioning

confidence: 99%

Gln-222 in Transmembrane Domain 4 and Gln-526 in Transmembrane Domain 9 Are Critical for Substrate Recognition in the Yeast High Affinity Glutathione Transporter, Hgt1p

Kaur¹,

Bachhawat

2009

Journal of Biological Chemistry

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Hgt1p, a member of the oligopeptide transporter family, is a high affinity glutathione transporter from the yeast Saccharomyces cerevisiae. We have explored the role of polar or charged residues in the putative transmembrane domains of Hgt1p to obtain insights into the structural features of Hgt1p that govern its substrate specificity. A total of 22 charged and polar residues in the predicted transmembrane domains and other conserved regions were subjected to alanine mutagenesis. Functional characterization of these 22 mutants identified 11 mutants which exhibited significant loss in functional activity. All 11 mutants except T114A had protein expression levels comparable with wild type, and all except E744A were proficient in trafficking to the cell surface. Kinetic analyses revealed differential contributions toward the functional activity of Hgt1p by these residues and identified Asn-124 in transmembrane domain 1 (TMD1), Gln-222 in TMD4, Gln-526 in TMD9, and Glu-544, Arg-554, and Lys-562 in the intracellular loop region 537-568 containing the highly conserved proline-rich motif to be essential for the transport activity of the protein. Furthermore, mutants Q222A and Q526A exhibited a nearly 4-and 8-fold increase in the K m for glutathione. Interestingly, although Gln-222 is widely conserved among other functionally characterized oligopeptide transporter family members including those having a different substrate specificity, Gln-526 is present only in Hgt1p and Pgt1, the only two known high affinity glutathione transporters. These results provide the first insights into the substrate recognition residues of a high affinity glutathione transporter and on residues/helices involved in substrate translocation in the structurally uncharacterized oligopeptide transporter family.Hgt1p or ScOpt1p, a polytopic membrane protein, from the yeast Saccharomyces cerevisiae, was the first high affinity glutathione transporter to be identified in any system (1). Hgt1p belongs to a relatively novel family of transporters, the oligopeptide transporter (OPT) 3 family, that contains a large number of fungal, plant, and prokaryotic members (2). The functional characterizations of a few of the fungal and plants members have demonstrated their ability to transport oligopeptides, glutathione, and metal-secondary amino acid conjugates by harnessing the proton gradient across the plasma membrane (3-7). Furthermore, these studies have also highlighted the physiological significance of this family in assimilation/mobilization of oligopeptides as nutrients in fungi and plants and in maintenance of metal homeostasis in plants. However, the majority of the members are yet uncharacterized and need to be defined with respect to their substrate specificity and physiological role.A complete lack of information on the structural features of the OPT family further limits our understanding of this large, uncharacterized family. Identification of residues or motifs critical for substrate recognition among the functionally characterized members woul...

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Schizosaccharomyces pombe isp4 encodes a transporter representing a novel family of oligopeptide transporters

Cited by 81 publications

References 47 publications

Expression analysis and characterization of rice oligopeptide transport gene (OsOPT10) that contributes to salt stress tolerance

Expression analysis and characterization of rice oligopeptide transport gene (OsOPT10) that contributes to salt stress tolerance

Expression Profiles of Arabidopsis thaliana in Mineral Deficiencies Reveal Novel Transporters Involved in Metal Homeostasis

Gln-222 in Transmembrane Domain 4 and Gln-526 in Transmembrane Domain 9 Are Critical for Substrate Recognition in the Yeast High Affinity Glutathione Transporter, Hgt1p

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