EC Number   |
General Information |
Reference |
|---|
  2.7.1.181 | malfunction |
construction of a chromosomal wbdDO9a::aacC1 mutation by allelic exchange. Membranes of the mutant are still able to synthesize O9a polymannan in vitro, although the chain length is increased relative to that made by the parent |
-, 722640 |
| 2.7.1.181 | malfunction |
membrane preparations from a wbdD mutant have severely diminished mannosyltransferase activity in vitro, and no significant amounts of the WbdA protein are targeted to the membrane fraction. Expression of a polypeptide comprising the WbdD C-terminal region is sufficient to restore both proper localization of WbdA and mannosyltransferase activity |
-, 722664 |
| 2.7.1.181 | more |
structural requirements for glycan recognition by the CBM, overview |
-, 757222 |
| 2.7.1.181 | physiological function |
chain-terminator enzyme WbdD caps the nonreducing end of the glycan with a methylphosphate moiety and thereby establishes chain-length distribution. A carbohydrate-binding module (CBM) in the ABC transporter recognizes terminated glycans, ensuring that only mature O-antigen polysaccharide (O-PS) is exported and incorporated into LPS. Enzyme WbdD is bifunctional and shows both kinase and methyltransferase activities. WbdD mutants reveal that although the kinase activity is solely responsible for chain-length regulation, both activities are essential for CBM recognition and export. Direct interaction between the CBM and the terminal methyl group. CBM can bind the O-PS only with the native repeat unit, revealing that methylphosphate is essential but not sufficient for substrate recognition and export. Essential to this chain-length regulation strategy is a quality control mechanism on the ABC transporter protein complex, which ensures that only terminated (and chain-regulated) O-PS is exported for assembly on the cell surface. O-PS ABC transporters are composed of homodimers of the transmembrane domain protein (Wzm) and the nucleotide-binding domain protein (Wzt). Wzt possesses a C-terminal CBM, which is specific for its cognate O-PS. Binding of O-PS by the CBM is a prerequisite for transport, and removal or mutation of the CBM abrogates export. WbdD kinase activity is solely responsible for arresting O9a O-PS polymerization. Catalytic mechanism, overview |
-, 757222 |
| 2.7.1.181 | physiological function |
the glycan of the polymannose O-polysaccharide of Escherichia coli O9a is assembled on a 55-carbon lipid acceptor (undecaprenol phosphate) in the inner (cytoplasmic) membrane. Chain extension is mediated by three mannosyltransferases, designated WbdCBA, and occurs by the addition of mannose residues to the non-reducing terminus of the glycan. The chain length of the O9a O-polysaccharide is controlled by the activity of the WbdD protein by addition of methylphosphate to the non-reducing terminus |
-, 722733 |
| 2.7.1.181 | physiological function |
the WbdD proteins control the chain length of the Escherichia coli O9a polymannan by modifying the nonreducing end of nascent undecaprenol diphosphate-linked polymer. Overexpression of WbdD decreases O-polysaccharide chain length. WbdD activity coordinates polymannan chain termination with export across the inner membrane |
-, 722640 |
| 2.7.1.181 | physiological function |
WbdD controls polymerization reaction in biosynthesis of the O-polysaccharide by coordinating the correct membrane association required for activity of one of the critical mannosyltransferases, WbdA. Identification of regions in the C terminus of WbdD that contribute to the interaction |
-, 722664 |
