EC Number   |
General Information |
Reference |
|---|
   2.1.1.294 | 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 |
| 2.1.1.294 | more |
direct interaction between the CBM and the terminal methyl group. The nonreducing terminal modification is the sole contributor to ABC transporter WztO9a-C O-PS recognition |
-, 757222 |
| 2.1.1.294 | physiological function |
In Escherichia coli O9a, the peripheral membrane protein WbdD terminates polymerization by adding a methyl phosphate to the non-reducing end of the nascent O9a polymer. The O9a system is a representative of the widespread ATP-binding cassette transporter-dependent assembly pathway. This terminal modification is required for recognition and export of the completed O-PS across the cytoplasmic membrane by its cognate ATP-binding cassette transporter. The recognition event is mediated by the nucleotide-binding domain polypeptide of the transporter, which possesses a serotype-specific carbohydrate-binding module that only binds terminated O-PS chains. The WbdD terminator plays an additional pivotal structural role in recruiting WbdA to the membrane. The stoichiometry of WbdA:WbdD in active complexes is a critical factor in establishing the chain length distribution of the resulting glycans. The size of the O9a polysaccharide is determined by the chain-terminating dual kinase/methyltransferase (WbdD) that is tethered to the membrane and recruits polymerase/glycosyltransferase WbdA into an active enzyme complex by protein-protein interactions. Identification via bacterial two-hybrid analysis of a surface-exposed alpha-helix in the C-terminal mannosyltransferase domain of WbdA as the site of interaction with WbdD, the C-terminal domain was unable to interact with WbdD in the absence of its N-terminal partner. The WbdD protein orchestrates critical localization and coordination of activities involved in chain extension and termination. Complex domain interactions are needed to position the polymerase components appropriately for assembly into a functional complex located at the cytoplasmic membrane. WbdD is therefore a central player in a sophisticated quality control system that dictates the distribution of chain lengths and marks those chains with a terminal export tag |
736468 |
| 2.1.1.294 | 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 |
| 2.1.1.294 | metabolism |
the enzyme WbdD takes part in the biosynthesis of lipopolysaccharide O-antigen in Escherichia coli strain O9a, genetic organization, LPS structure, and pathway, overview. Model for export of lipopolysaccharide (LPS) O-antigen polysaccharide (O-PS) via ABC transporters. In O9a biosynthesis, the 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-PS is exported and incorporated into LPS. Each 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 |
-, 757222 |
| 2.1.1.294 | metabolism |
the enzyme WbdD takes part in the biosynthesis of lipopolysaccharide O-antigen in Klebsiella pneumoniae strain O7, pathway overview |
-, 757222 |
| 2.1.1.294 | physiological function |
the enzyme WbdD takes part in the biosynthesis of lipopolysaccharide O-antigen in Klebsiella pneumoniae strain O7, pathway overview. In the simpler process exhibited by Klebsiella pneumoniae serotype O2a, the O-PS is polymerized to completion within the cytosol by a biosynthetic enzyme complex. The chain-length distribution is controlled by the relative activities of a complex of glycosyltransferase (GT) enzymes and the ABC transporter. The O2a ABC transporter does not possess strict O-PS specificity, and it can export polymers with diverse repeat-unit structures, but polymerization and export are obligatorily coupled |
-, 757222 |
| 2.1.1.294 | physiological function |
the glycan of the polymannose O-polysaccharide of Escherichia coli O9a is assembled on a 55-carbon lipid acceptor (undecaprenyl 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 |
| 2.1.1.294 | malfunction |
The immune response to Pseudomonas aeruginosa in a Pseudomonas-zebrafish hindbrain infection model shows that deletion of warA or sadC does not reduce bacterial load. A phenotype of significantly increased neutrophil recruitment is observed for a warA deletion mutant. Infection with a warA mutant also induces TNF-alpha mRNA levels significantly higher than wild-type infected larvae |
-, 757781 |
| 2.1.1.294 | physiological function |
the more intricate Escherichia coli serotype O9a O-antigen polysaccharide (O-PS) assembly system incorporates an additional mechanism that imposes a stricter level of control over chain length. This requires the installation of a chain-terminating residue that creates an export signal recognized by a carbohydrate-binding module (CBM) attached to the ABC transporter. In this system, polymerization and export can be temporally uncoupled in vitro. In O9a biosynthesis, a 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-PS is exported and incorporated into LPS. Enzyme WbdD has both kinase and methyltransferase activities. Although the kinase activity is solely responsible for chain-length regulation, both activities are essential for CBM recognition and export. Each 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 |
-, 757222 |
