PMID:8631969

Citation	Brooke, JS and Valvano, MA (1996) Biosynthesis of inner core lipopolysaccharide in enteric bacteria identification and characterization of a conserved phosphoheptose isomerase. J. Biol. Chem. 271:3608-14
Abstract	The lpcA locus has been identified in Escherichia coli K12 novobiocin-supersensitive mutants that produce a short lipopolysaccharide (LPS) core which lacks glyceromannoheptose and terminal hexoses. We have characterized lpcA as a single gene mapping around 5.3 min (246 kilobases) on the E. coli K12 chromosome and encoding a 22.6-kDa cytosolic protein. Recombinant plasmids containing only lpcA restored a complete core LPS in the E. coli strain chi711. We show that this strain has an IS5-mediated chromosomal deletion of 35 kilobases that eliminates lpcA. The LpcA protein showed discrete similarities with a family of aldose/ketose isomerases and other proteins of unknown function. The isomerization of sedoheptulose 7-phosphate, into a phosphosugar presumed to be D-glycero-D-mannoheptose 7-phosphate, was detected in enzyme reactions with cell extracts of E. coli lpcA+ and of lpcA mutants containing the recombinant lpcA gene. We concluded that LpcA is the phosphoheptose isomerase used in the first step of glyceromannoheptose synthesis. We also demonstrated that lpcA is conserved among enteric bacteria, all of which contain glyceromannoheptose in the inner core LPS, indicating that LpcA is an essential component in a conserved biosynthetic pathway of inner core LPS.
Links	PubMed
Keywords	Aldose-Ketose Isomerases; Amino Acid Sequence; Animals; Base Sequence; Carbohydrate Epimerases/chemistry; Carbohydrate Epimerases/genetics; Carbohydrate Epimerases/metabolism; Carbohydrate Metabolism; Carbohydrates/analysis; Chromatography, High Pressure Liquid; Chromosome Deletion; Chromosomes, Bacterial; Conserved Sequence; Enterobacteriaceae/enzymology; Enterobacteriaceae/genetics; Enterobacteriaceae/immunology; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli/immunology; Genes, Bacterial; Genotype; Lipopolysaccharides/biosynthesis; Molecular Sequence Data; Rats; Restriction Mapping; Sequence Homology, Amino Acid
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Main Points of the Paper

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Materials and Methods Used

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Phenotype Annotations

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Phenotype of	Taxon Information	Genotype Information (if known)	Condition Information	OMP ID	OMP Term Name	ECO ID	ECO Term Name	Notes	Status
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: X705 NCBI Taxon ID: 83333	Genotype of Reference Strain: lpcA+ Genotype of Experimental Strain : lpcA- in Strain X711	Reference Condition:					The mutation caused a decrease in the size of the core oligosaccharide. See figure 1 lane 2.
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: X705 NCBI Taxon ID: 83333	Genotype of Reference Strain: rfa+ Genotype of Experimental Strain : rfa-1 in D21e7	Reference Condition:					The mutation caused a the production of a shorter LPS core though not as small as X711. See figure 1 lane 5.
a mutation or genetic difference within a strain	Taxon: Escherichia coli Strain: K-12 Substrain: X705 NCBI Taxon ID: 83333	Genotype of Reference Strain: rfa+ Genotype of Experimental Strain : rfaG(del) rfaP(del) rfaM(del) rfaN(del) rfaB(del)::CS2052	Reference Condition:					The mutation caused a the production of a shorter LPS core though not as small as X711. See figure 1 lane 6.
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Notes

• Based on LPS analysis it was concluded that _X711 lacks heptose in its core LPS.

References

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