2r5o

[[Image:2r5o.jpg|left|200px]]

|PDB= 2r5o |SIZE=350|CAPTION= <scene name='initialview01'>2r5o</scene>, resolution 1.300&Aring;

|SITE=

|LIGAND= <scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=NA:SODIUM+ION'>NA</scene> and <scene name='pdbligand=PG4:TETRAETHYLENE GLYCOL'>PG4</scene>

|ACTIVITY=

|GENE= ORF431 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=562 Escherichia coli])

 

 

 

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.

 

==About this Structure==

2R5O is a [[Single protein]] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2R5O OCA].

 

==Reference==

Substrate binding by a bacterial ABC transporter involved in polysaccharide export., Cuthbertson L, Kimber MS, Whitfield C, Proc Natl Acad Sci U S A. 2007 Dec 4;104(49):19529-34. Epub 2007 Nov 21. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/18032609 18032609]

[[Category: Single protein]]

[[Category: Cuthbertson, L.]]

[[Category: Kimber, M S.]]

[[Category: Whitfield, C.]]