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Structure and transport mechanism of the bacterial oxalate transporter OxlT

Teruhisa Hirai1, Sriram Subramaniam

  • 1Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.

Biophysical Journal
|September 2, 2004
PubMed

Insights

The oxalate transporter (OxlT) undergoes a rocking motion between open and closed states to transport oxalate. Positively charged residues in the central cavity are key to this conformational change.

Area of Science:

  • Biochemistry
  • Structural Biology
  • Molecular Biology

Background:

  • Major facilitator superfamily (MFS) proteins transport diverse substrates across cell membranes.
  • The oxalate transporter (OxlT) from Oxalobacter formigenes exchanges formate for oxalate.

Purpose of the Study:

  • To elucidate the conformational changes of OxlT during oxalate transport.
  • To develop a structural model for OxlT-mediated transport.

Main Methods:

  • Cryo-electron microscopy (cryo-EM) to determine the 3D structure of oxalate-bound OxlT.
  • Modeling the open state using structures of related MFS transporters (GlpT, LacY).

Main Results:

  • A structural model shows OxlT undergoes a rocking motion between two halves for transport.
  • Two positively charged residues (Arg-272, Lys-355) are identified in the central cavity.
  • Electrostatic interactions with oxalate likely drive the conformational change.

Conclusions:

  • OxlT functions via a concerted rocking mechanism.
  • Electrostatic interactions involving Arg-272 and Lys-355 are crucial for oxalate binding and transport.
  • This study provides insights into MFS transporter mechanisms.

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