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Tripeptide binding in a proton-dependent oligopeptide transporter
Maria Martinez Molledo1, Esben M Quistgaard1,2, Christian Löw1,2
1Centre for Structural Systems Biology (CSSB), DESY and European Molecular Biology Laboratory Hamburg, Hamburg, Germany.
FEBS Letters
|September 9, 2018
Summary
Proton-dependent oligopeptide transporters (POTs) bind tripeptides similarly to dipeptides. A new structure reveals a unique pocket accommodating diverse tripeptide side chains, clarifying recognition mechanisms.
Area of Science:
- Membrane transport
- Structural biology
- Biochemistry
Background:
- Proton-dependent oligopeptide transporters (POTs) facilitate di- and tripeptide uptake.
- The transport mechanism for dipeptides is understood, but tripeptide recognition remains unclear.
Purpose of the Study:
- To elucidate the binding and recognition mechanism of tripeptides by POT transporters.
- To investigate the structural basis for tripeptide accommodation within the POT transporter.
Main Methods:
- Biochemical characterization of tripeptide binding affinities to Streptococcus thermophilus POT transporter (PepTSt).
- X-ray crystallography to determine the 2.3-Å structure of PepTSt in complex with Phe-Ala-Gln.
Main Results:
- Tripeptides (Phe-Ala-Xxx) exhibit binding affinities comparable to dipeptides for PepTSt.
- The crystal structure reveals conserved binding of the first two residues (Phe-Ala) and a novel side chain pocket for the third residue (Gln).
- This newly identified pocket is adaptable, suggesting it can accommodate various tripeptide side chains.
Conclusions:
- POT transporters recognize tripeptides through a mechanism similar to dipeptides, with an adaptable pocket for the third residue.
- This finding provides structural insights into tripeptide transport and has implications for drug development targeting POTs.
Keywords:
POTsmajor facilitator superfamily (MFS)membrane protein crystallographypeptide bindingpeptide transportersMore Related Videos
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