2R5O

Crystal structure of the C-terminal domain of wzt

Summary for 2R5O

• Entry DOI: 10.2210/pdb2r5o/pdb
• Descriptor: Putative ATP binding component of ABC-transporter, CHLORIDE ION, SODIUM ION, ... (5 entities in total)
• Functional Keywords: abc transporter, immunoglobulin fold, carbohydrate binding, domain swapping, o antigen export, atp-binding, nucleotide-binding, transport protein
• Biological source: Escherichia coli
• Total number of polymer chains: 2
• Total formula weight: 43113.10

Authors

Kimber, M.S.,Cuthbertson, L.,Whitfield, C. (deposition date: 2007-09-04, release date: 2007-12-25, Last modification date: 2024-02-21)

Primary citation

Cuthbertson, L.,Kimber, M.S.,Whitfield, C.
Substrate binding by a bacterial ABC transporter involved in polysaccharide export.
Proc.Natl.Acad.Sci.Usa, 104:19529-19534, 2007

PubMed Abstract: ATP-binding-cassette (ABC) transporters are responsible for the export of a wide variety of cell-surface glycoconjugates in both Gram-positive and Gram-negative bacteria. These include the O-antigenic polysaccharide (O-PS) portion of lipopolysaccharide, a crucial virulence determinant in Gram-negative pathogens. O-PSs are synthesized by one of two fundamentally different pathways. Escherichia coli O serotypes O8 and O9a provide the prototype systems for studying O-PS export via ABC transporters. The transporter is composed of the transmembrane component Wzm and the nucleotide-binding component Wzt. Although the N-terminal domain of Wzt is a conventional ABC protein, the C-terminal domain of Wzt (C-Wzt) is a unique structural element that determines the specificity of the transporter for either the O8 or O9a O-PS. We show here that the two domains of Wzt can function when expressed as separate polypeptides; both are essential for export. In vitro, C-Wzt binds its cognate O-PS by recognizing a residue located at the nonreducing end of the polymer. The crystal structure of C-Wzt(O9a) is reported here and reveals a beta sandwich with an immunoglobulin-like topology that contains the O-PS-binding pocket. Substrate interactions with nucleotide-binding domains have been demonstrated in an ABC exporter previously. However, to our knowledge substrate binding by a discrete, cytoplasmic accessory domain in an extended nucleotide-binding domain polypeptide has not previously been demonstrated. Elucidation of the substrate-recognition system involved in O-PS export provides insight into the mechanism that coordinates polymer biosynthesis, termination, and export.

PubMed: 18032609
DOI: 10.1073/pnas.0705709104

Experimental method

X-RAY DIFFRACTION (1.3 Å)