Structural basis for polyspecificity in the
            <scp>POT</scp>
            family of proton‐coupled oligopeptide transporters

Lyons, Joseph A.; Parker, Joanne L.; Solcan, Nicolae; Brinth, Alette; Li, Dianfan; Shah, Syed Tasadaque Ali; Caffrey, Martin; Newstead, Simon

doi:10.15252/embr.201338403

Cited by 105 publications

(212 citation statements)

References 39 publications

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“…In a Ptr2 structural model based on the crystal structure of S. oneidensis PepT so (PDB 2XUT), a dipeptide is situated in a peptide-binding pocket that is surrounded by multiple amino acid residues, including R93, Y138, K205, and E480. Most recently, there was one substantive publication on structural issues with the substrate multispecificity of PepT st (44). The study presented crystal structures of di-and tripeptide-bound complexes of PepT st , which revealed that AlaPhe was oriented laterally in the binding site, whereas Ala-Ala-Ala showed an alternative vertical binding mode.…”

Section: Discussionmentioning

confidence: 99%

Functional Implications and Ubiquitin-Dependent Degradation of the Peptide Transporter Ptr2 in Saccharomyces cerevisiae

et al. 2014

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The peptide transporter Ptr2 plays a central role in di-or tripeptide import in Saccharomyces cerevisiae. Although PTR2 transcription has been extensively analyzed in terms of upregulation by the Ubr1-Cup9 circuit, the structural and functional information for this transporter is limited. Here we identified 14 amino acid residues required for peptide import through Ptr2 based on the crystallographic information of Streptococcus thermophilus peptide transporter PepT st and based on the conservation of primary sequences among the proton-dependent oligopeptide transporters (POTs). Expression of Ptr2 carrying one of the 14 mutations of which the corresponding residues of PepT st are involved in peptide recognition, salt bridge interaction, or peptide translocation failed to enable ptr2⌬trp1 cell growth in alanyl-tryptophan (Ala-Trp) medium. We observed that Ptr2 underwent rapid degradation after cycloheximide treatment (half-life, approximately 1 h), and this degradation depended on Rsp5 ubiquitin ligase. The ubiquitination of Ptr2 most likely occurs at the N-terminal lysines 16, 27, and 34. Simultaneous substitution of arginine for the three lysines fully prevented Ptr2 degradation. Ptr2 mutants of the presumed peptide-binding site (E92Q, R93K, K205R, W362L, and E480D) exhibited severe defects in peptide import and were subjected to Rsp5-dependent degradation when cells were moved to Ala-Trp medium, whereas, similar to what occurs in the wild-type Ptr2, mutant proteins of the intracellular gate were upregulated. These results suggest that Ptr2 undergoes quality control and the defects in peptide binding and the concomitant conformational change render Ptr2 subject to efficient ubiquitination and subsequent degradation.

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Section: Discussionmentioning

confidence: 99%

Functional Implications and Ubiquitin-Dependent Degradation of the Peptide Transporter Ptr2 in Saccharomyces cerevisiae

et al. 2014

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“…Insights into the biochemical basis for peptide binding and selectivity have recently come from three different POT family members crystallised in complex with peptides [17,34,35]. Detailed analyses of the binding interactions in these structures have been published recently [19,29] and will not be discussed in detail here.…”

Section: Peptide Binding and The Role Of Specificity Pockets In Liganmentioning

confidence: 99%

“…These two regions are opposite an acidic patch on TM7 and 10 in PepT St and a hydrophobic pocket, constructed of aromatic side chains from TM's 2, 11. Several lines of biochemical evidence suggest that ligand selectivity is the result of interactions between the side chains of the peptide and these pockets [34][35][36], which in turn promote the conformational changes required for transport. It is unclear what role, if any, symmetry plays in peptide recognition.…”

Section: Peptide Binding and The Role Of Specificity Pockets In Liganmentioning

confidence: 99%

Symmetry and Structure in the POT Family of Proton Coupled Peptide Transporters

Newstead

2017

Symmetry

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Abstract:The POT family of proton coupled oligopeptide transporters belong to the Major Facilitator Superfamily of secondary active transporters and are found widely distributed in bacterial, plant, fungal and animal genomes. POT transporters use the inwardly directed proton electrochemical gradient to drive the concentrative uptake of di-and tri-peptides across the cell membrane for metabolic assimilation. Mammalian members of the family, PepT1 and PepT2, are responsible for the uptake and retention of dietary protein in the human body, and due to their promiscuity in ligand recognition, play important roles in the pharmacokinetics of drug transport. Recent crystal structures of bacterial and plant members have revealed the overall architecture for this protein family and provided a framework for understanding proton coupled transport within the POT family. An interesting outcome from these studies has been the discovery of symmetrically equivalent structural and functional sites. This review will highlight both the symmetry and asymmetry in structure and function within the POT family and discuss the implications of these considerations in understanding transport and regulation.

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“…Both the amino and the carboxy terminals are on the cytoplasmic side of the membrane. These proteins also contain potential sites in the intracellular loop for protein kinase-dependent phosphorylation (Chen et al 2002;Lyons et al 2014). The crystal structures of di-and tripeptide-bound complexes of a bacterial homolog of PepT1 revealed at least two mechanisms for peptide recognition.…”

mentioning

confidence: 99%

“…The crystal structures of di-and tripeptide-bound complexes of a bacterial homolog of PepT1 revealed at least two mechanisms for peptide recognition. The dipeptide was laterally oriented in the binding site, whereas the tripeptide revealed an alternative vertical binding mode (Lyons et al 2014). Molecular studies on the regulation of PepT gene expression in mammals indicates that the promoter of PepT1 has both an amino acid responsive element (Fei et al 2000) and binding sites for transcription factors, such as Cdx2, PPARα and Sp1 (Shiraga et al 1999).…”

mentioning

confidence: 99%

Identification and characterization of bovine mammary peptide transporters in response to tripeptide and lactogenic hormone treatment

Cui¹,

Zhang²,

Guo³

et al. 2017

CZECH J ANIM SCI

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Cui Y., Zhang X., Guo C., Du R., Ailun G., Ao C., Gao M. (2017): Identification and characterization of bovine mammary peptide transporters in response to tripeptide and lactogenic hormone treatment. Czech J. Anim. Sci., 62, 296-305.Oligopeptide transportation is mediated by the peptide transporter (PepT), which consists of two isoforms, PepT1 and PepT2. Because PepT play essential roles in amino acid metabolism and cell growth, the aim of the present study was to identify these transporters in bovine mammary glands and to analyze the potential functions of these transporters in mammary epithelial cells. Abundance of PepT1 and PepT2 mRNA was successfully measured in both mammary glands and cultured mammary epithelial cells. In addition, the two proteins were examined using immunohistochemistry, immunocytochemistry, and Western blots. The response of mammary epithelial cells to tripeptide and lactogenic hormone treatment was assayed. The PepT mRNA abundance of cultured epithelial cells and secreted protein in the culture medium were increased after tripeptide substitution and addition of hormones such as insulin, hydrocortisone, and prolactin. The response of mammary epithelial cells to tripeptide and hormone treatments suggests that PepT affects the mammary gland function and increases bovine milk production.

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Structural basis for polyspecificity in the POT family of proton‐coupled oligopeptide transporters

Cited by 105 publications

References 39 publications

Functional Implications and Ubiquitin-Dependent Degradation of the Peptide Transporter Ptr2 in Saccharomyces cerevisiae

Functional Implications and Ubiquitin-Dependent Degradation of the Peptide Transporter Ptr2 in Saccharomyces cerevisiae

Symmetry and Structure in the POT Family of Proton Coupled Peptide Transporters

Identification and characterization of bovine mammary peptide transporters in response to tripeptide and lactogenic hormone treatment

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