| Comment | This enzyme has been implicated in the formation of the acetamido moiety (sugar-NC(=NH)CH3) which is found on some exopolysaccharides and is positively charged at neutral pH. The reaction involves ligation of ammonia with a sugar N-acetyl group, displacing water. In E. coli (O145 strain) and Pseudomonas aeruginosa (O12 strain) this gene is known as wbuX and ifnA respectively and likely acts on sialic acid [1]. In Campylobacter jejuni, the gene is known as pseA and acts on pseudaminic acid in the process of flagellin glycosylation [2]. In other Pseudomonas strains and various organisms it is unclear what the identity of the sugar substrate is, and in fact, the phylogenetic tree of this family sports a considerably deep branching suggestive of possible major differences in substrate structure. Nevertheless, the family is characterized by a conserved tetracysteine motif (CxxC.....[GN]xCxxC) possibly indicative of a metal binding site, as well as an invariable contextual association with homologs of the HisH and HisF proteins known as WbuY and WbuZ, respectively. These two proteins are believed to supply the enzyme with ammonium by hydrolysis of glutamine and delivery through an ammonium conduit [3]. |
| References | RN [1]
RM PMID:18156256
RT lfnA from Pseudomonas aeruginosa O12 and wbuX from Escherichia coli O145 encode membrane-associated proteins and are required for expression of 2,6-dideoxy-2-acetamidino-L-galactose in lipopolysaccharide O antigen.
RA King JD, Mulrooney EF, Vinogradov E, Kneidinger B, Mead K, Lam JS
RL J Bacteriol. 2008 Mar;190(5):1671-9. Epub 2007 Dec 21.
RN [2]
RM PMID:16684771
RT Functional characterization of the flagellar glycosylation locus in Campylobacter jejuni 81-176 using a focused metabolomics approach.
RA McNally DJ, Hui JP, Aubry AJ, Mui KK, Guerry P, Brisson JR, Logan SM, Soo EC
RL J Biol Chem. 2006 Jul 7;281(27):18489-98. Epub 2006 May 9.
RN [3]
RM PMID:15629947
RT Structural and genetic characterization of enterohemorrhagic Escherichia coli O145 O antigen and development of an O145 serogroup-specific PCR assay.
RA Feng L, Senchenkova SN, Tao J, Shashkov AS, Liu B, Shevelev SD, Reeves PR, Xu J, Knirel YA, Wang L
RL J Bacteriol. 2005 Jan;187(2):758-64. |
