These lipopolysaccharide kinases are related to protein kinases Pfam:PF00069. This family includes waaP (rfaP) gene product is required for the addition of phosphate to O-4 of the first heptose residue of the lipopolysaccharide (LPS) inner core region. It has previously been shown that WaaP is necessary for resistance to hydrophobic and polycationic antimicrobials in E. coli and that it is required for virulence in invasive strains of S. enterica [1].

1: Purification and characterization of WaaP from Escherichia coli, a lipopolysaccharide kinase essential for outer membrane stability. Yethon JA, Whitfield C; J Biol Chem 2001;276:5498-5504. PMID:11069912

2: Lipopolysaccharide phosphorylating enzymes encoded in the genomes of Gram-negative bacteria are related to the eukaryotic protein kinases. Krupa A, Srinivasan N; Protein Sci 2002;11:1580-1584. PMID:12021457

3: A Haemophilus influenzae gene that encodes a membrane bound 3-deoxy-D-manno-octulosonic acid (Kdo) kinase. Possible involvement of kdo phosphorylation in bacterial virulence. White KA, Lin S, Cotter RJ, Raetz CR; J Biol Chem 1999;274:31391-31400. PMID:10531340