Disease relevance of rfaD

• The location of the rfaD gene on the physical map of the Escherichia coli chromosome was determined [1].
• However, the LPS core of the mutant migrated slightly less rapidly on sodium dodecyl sulfate-polyacrylamide gel electrophoresis than wild-type or revertant core LPS and did not resemble Re chemotype LPS core obtained from Salmonella rfaC and rfaD mutants [2].
• Identification of the ADP-L-glycero-D-manno-heptose-6-epimerase (rfaD) and heptosyltransferase II (rfaF) biosynthesis genes from nontypeable Haemophilus influenzae 2019 [3].
• We have identified an rfaD homologue in Vibrio cholerae O1 [4].
• A mutation in the Neisseria gonorrhoeae rfaD homolog results in altered lipooligosaccharide expression [5].

High impact information on rfaD

• However, O139 strains have retained rfaD and have a single open reading frame closely related to three small open reading frames of the O1 rfb region [6].
• Two chimeric colicin E1 plasmids carrying the coding sequence of the rfaD+ locus have been selected and shown to complement the rfaD phenotype [7].
• The sigma 32 transcription factor is essential for maximal htrM gene transcription, since htrM RNA transcripts are made at reduced rates in a rpoH null mutant background [8].
• The rfaD gene encodes a polypeptide of 35 kDa and the rfaF encodes a protein of 39 kDa, as demonstrated by in vitro transcription-translation studies [3].
• Additional studies verified that in the rfaD mutant strain, D-glycero-D-manno-heptose is added to the LOS molecule in place of the usual L-glycero-D-manno-heptose [3].

Chemical compound and disease context of rfaD

• The rfaD gene of Escherichia coli encodes ADP-L-glycero-D-mannoheptose-6- epimerase, an enzyme required for the biosynthesis of the lipopolysaccharide (LPS) precursor ADP-L-glycero-D- mannoheptose, associated with production of the core oligosaccharide [4].

Biological context of rfaD

• Primer extension studies were used to define the regulatory region of the rfaD gene [1].
• This plasmid was able to complement both rfaD and rfaF mutants of S. typhimurium [3].
• The complete nucleotide sequence of rfaD and the flanking DNA has been determined, and rfaD would appear to be the only gene homologous to known LPS core biosynthesis genes in this region [4].
• In Vibrio cholerae serogroup O1, rfaD is closely linked to the rfb operon [4].
• Comparison with the E. coli rfaD shows many similar structural features such as the ADP-binding beta alpha beta fold at the N terminus, as well as a high degree of homology of both the nucleotide and amino-acid sequences [4].

Associations of rfaD with chemical compounds

• The rfaD gene encodes ADP-L-glycero-D-mannoheptose-6-epimerase, an enzyme required for the biosynthesis of the lipopolysaccharide precursor ADP-L-glycerol-D-mannoheptose [1].

References