Taxonomic group: bacteria / Proteobacteria
(Phylum: Proteobacteria)
Associated disease: infection due to Escherichia coli [ICD11:
XN6P4 
]
NCBI PubMed ID: 7682279Journal NLM ID: 8712028Publisher: Blackwell Publishing
Institutions: Department of Microbiology, University of Sydney, Sydney, NSW 2006, Australia
We report the identification and sequence from Escherichia coli and Salmonella enterica strains of the cld gene, encoding the chain-length determinant (CLD) which confers a modal distribution of chain length on the O-antigen component of lipopolysaccharide (LPS). The distribution of chain lengths in the absence of this gene fits a model in which as the chain is extended there is a constant probability of 0.165 of transfer of growing chain to LPS core, with termination of chain extension. The data for E. coli 0111 fit a model in which the CLD reduces this probability for short chains and increases it to 0.4 for longer chains, leading to a reduced number of short chain molecules but an increase in numbers of longer molecules and transfer of essentially all molecules by chain length 21. We put forward a model for O-antigen polymerase which resembles the ribosome and fatty acid synthetase in having two sites, with the growing chain being transferred from a D site onto the new unit at the R site to extend the chain and then back to the D site to repeat the process. It is proposed that the CLD protein and polymerase form a complex which has two states:'E'facilitating extension and T facilitating transfer to core. The complex is postulated to enter the E state as O-antigen polymerization starts, and to shift to the T state after a predetermined time, the CLD acting as a molecular clock. The CLD is not O-antigen or species-specific but the modal value does depend on the source of the cld gene.
biosynthesis, transfer, gene, O-antigen, repeating unit, Salmonella enterica, sequence, synthetase
Structure type: polymer chemical repeating unit
Location inside paper: p.726, fig.1A
Compound class: O-polysaccharide, O-antigen
Contained glycoepitopes: IEDB_135813,IEDB_136906,IEDB_137340,IEDB_137472,IEDB_141794,IEDB_141807,IEDB_142488,IEDB_144998,IEDB_146664,IEDB_151528,IEDB_151531,IEDB_190606,IEDB_983931,SB_192,SB_7
Methods: genetic methods
Biosynthesis and genetic data: genetic data
Related record ID(s): 20510, 20672, 22734, 24880
NCBI Taxonomy refs (TaxIDs): 1055535Reference(s) to other database(s): GTC:G38677MM, GlycomeDB:
3515
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There is only one chemically distinct structure:
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