3P03

Crystal structure of BetP-G153D with choline bound

Summary for 3P03

• Entry DOI: 10.2210/pdb3p03/pdb
• Descriptor: Glycine betaine transporter BetP, CHOLINE ION (2 entities in total)
• Functional Keywords: secondary transporter, transport protein
• Biological source: Corynebacterium glutamicum (Brevibacterium flavum)
• Cellular location: Cell membrane; Multi-pass membrane protein: P54582
• Total number of polymer chains: 3
• Total formula weight: 183285.70

Authors

Perez, C.,Ressl, S.,Ziegler, Z. (deposition date: 2010-09-27, release date: 2011-03-30, Last modification date: 2024-02-21)

Primary citation

Perez, C.,Koshy, C.,Ressl, S.,Nicklisch, S.,Kramer, R.,Ziegler, C.
Substrate specificity and ion coupling in the Na(+)/betaine symporter BetP.
Embo J., 30:1221-1229, 2011

PubMed Abstract: BetP is an Na(+)-coupled betaine-specific transporter of the betaine-choline-carnitine (BCC) transporter family involved in the response to hyperosmotic stress. The crystal structure of BetP revealed an overall fold of two inverted structurally related repeats (LeuT-fold) that BetP shares with other sequence-unrelated Na(+)-coupled symporters. Numerous structures of LeuT-fold transporters in distinct conformational states have contributed substantially to our understanding of the alternating access mechanism of transport. Nevertheless, coupling of substrate and co-transported ion fluxes has not been structurally corroborated to the same extent. We converted BetP by a single-point mutation--glycine to aspartate--into an H(+)-coupled choline-specific transporter and solved the crystal structure of this mutant in complex with choline. The structure of BetP-G153D demonstrates a new inward-facing open conformation for BetP. Choline binding to a location close to the second, low-affinity sodium-binding site (Na2) of LeuT-fold transporters is facilitated by the introduced aspartate. Our data confirm the importance of a cation-binding site in BetP, playing a key role in a proposed molecular mechanism of Na(+) and H(+) coupling in BCC transporters.

PubMed: 21364531
DOI: 10.1038/emboj.2011.46

Experimental method

X-RAY DIFFRACTION (3.35 Å)