PDBsum entry 5c76

Transport protein

PDB id: 5c76

Contents

Protein chains

564 a.a.

PDB id:

5c76

Name:

Transport protein

Title:

Atp-driven lipid-linked oligosaccharide flippase pglk in apo-inward facing state (2)

Structure:

Wlab protein. Chain: a, b, c, d. Engineered: yes

Source:

Campylobacter jejuni. Organism_taxid: 197. Gene: wlab. Expressed in: escherichia coli bl21(de3). Expression_system_taxid: 469008.

Resolution:

3.94Å R-factor: 0.277 R-free: 0.329

Authors:

C.Perez,S.Gerber,K.P.Locher

Key ref:

C.Perez et al. (2015). Structure and mechanism of an active lipid-linked oligosaccharide flippase. Nature, 524, 433-438. PubMed id: 26266984 DOI: 10.1038/nature14953

Date:

24-Jun-15 Release date: 19-Aug-15

Protein chains

O86150  (O86150_CAMJU) -  ABC transporter ATP-binding protein from Campylobacter jejuni

Seq: 564 a.a.

Struc: 564 a.a.*

* PDB and UniProt seqs differ at 3 residue positions (black crosses)

DOI no: 10.1038/nature14953

Nature 524:433-438 (2015)

PubMed id: 26266984

Structure and mechanism of an active lipid-linked oligosaccharide flippase.

C.Perez, S.Gerber, J.Boilevin, M.Bucher, T.Darbre, M.Aebi, J.L.Reymond, K.P.Locher.

ABSTRACT

The flipping of membrane-embedded lipids containing large, polar head groups is slow and energetically unfavourable, and is therefore catalysed by flippases, the mechanisms of which are unknown. A prominent example of a flipping reaction is the translocation of lipid-linked oligosaccharides that serve as donors in N-linked protein glycosylation. In Campylobacter jejuni, this process is catalysed by the ABC transporter PglK. Here we present a mechanism of PglK-catalysed lipid-linked oligosaccharide flipping based on crystal structures in distinct states, a newly devised in vitro flipping assay, and in vivo studies. PglK can adopt inward- and outward-facing conformations in vitro, but only outward-facing states are required for flipping. While the pyrophosphate-oligosaccharide head group of lipid-linked oligosaccharides enters the translocation cavity and interacts with positively charged side chains, the lipidic polyprenyl tail binds and activates the transporter but remains exposed to the lipid bilayer during the reaction. The proposed mechanism is distinct from the classical alternating-access model applied to other transporters.