RRC ID 35612
Author Klein G, Müller-Loennies S, Lindner B, Kobylak N, Brade H, Raina S.
Title Molecular and structural basis of inner core lipopolysaccharide alterations in Escherichia coli: incorporation of glucuronic acid and phosphoethanolamine in the heptose region.
Journal J Biol Chem
Abstract It is well established that lipopolysaccharide (LPS) often carries nonstoichiometric substitutions in lipid A and in the inner core. In this work, the molecular basis of inner core alterations and their physiological significance are addressed. A new inner core modification of LPS is described, which arises due to the addition of glucuronic acid on the third heptose with a concomitant loss of phosphate on the second heptose. This was shown by chemical and structural analyses. Furthermore, the gene whose product is responsible for the addition of this sugar was identified in all Escherichia coli core types and in Salmonella and was designated waaH. Its deduced amino acid sequence exhibits homology to glycosyltransferase family 2. The transcription of the waaH gene is positively regulated by the PhoB/R two-component system in a growth phase-dependent manner, which is coordinated with the transcription of the ugd gene explaining the genetic basis of this modification. Glucuronic acid modification was observed in E. coli B, K12, R2, and R4 core types and in Salmonella. We also show that the phosphoethanolamine (P-EtN) addition on heptose I in E. coli K12 requires the product of the ORF yijP, a new gene designated as eptC. Incorporation of P-EtN is also positively regulated by PhoB/R, although it can occur at a basal level without a requirement for any regulatory inducible systems. This P-EtN modification is essential for resistance to a variety of factors, which destabilize the outer membrane like the addition of SDS or challenge to sublethal concentrations of Zn(2+).
Volume 288(12)
Pages 8111-27
Published 2013-3-22
DOI 10.1074/jbc.M112.445981
PII M112.445981
PMID 23372159
PMC PMC3605630
MeSH Carbohydrate Conformation Carbohydrate Sequence Cell Membrane / metabolism Cell Membrane / physiology Escherichia coli / genetics Escherichia coli / metabolism* Escherichia coli Proteins / genetics* Escherichia coli Proteins / metabolism Escherichia coli Proteins / physiology Ethanolamines / metabolism* Gene Expression Regulation, Bacterial Glucuronic Acid / metabolism* Glycosyltransferases / genetics Heptoses / metabolism* Lipopolysaccharides / chemistry Lipopolysaccharides / metabolism* Membrane Proteins / genetics* Membrane Proteins / metabolism Membrane Proteins / physiology Molecular Sequence Annotation Molecular Sequence Data Transcription, Genetic
IF 4.238
Times Cited 24
Prokaryotes E. coli JW3927(ASKA) JW3590(ASKA)