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An unassigned DAHP synthase activity found only in pathogenic Escherichia coli strains
Author(s) -
Yep Alejandra,
Grmai Lydia,
Emanuele Anthony A.,
Woodard Ronald W.
Publication year - 2011
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.25.1_supplement.967.8
Subject(s) - shikimate pathway , escherichia coli , complementation , biology , gene , atp synthase , bacteria , aromatic amino acids , biochemistry , enzyme , microbiology and biotechnology , biosynthesis , strain (injury) , genetics , phenotype , anatomy
The enzyme 3‐deoxy‐D‐arabino‐heptulosonate 7‐phosphate synthase (DAHPS) catalyzes the first step of the shikimate biosynthetic pathway, which leads to the synthesis of aromatic amino acids. This pathway is essential in bacteria but absent from mammals, making it a suitable target for antibiotic therapy. Escherichia coli has three DAHPSs, encoded by the genes aroF , aroG , and aroH . AroF, AroG, and AroH are feedback inhibited by Tyr, Phe, and Trp, respectively. BLAST searches identified a previously uncharacterized DAHPS copy present only in extraintestinal pathogenic E. coli strains. The corresponding gene ( c1220 ) was cloned from E. coli CFT073, a strain responsible for most uncomplicated urinary tract infections (UTI). The ORF c1220 is highly upregulated during UTI (Snyder et al. (2004), Infect Immun 72:6373). Purified C1220 displays in vitro DAHPS activity uninhibited by Phe, Tyr, Trp, prephenate, or chorismate. Consistently, a model of C1220 shows conservation of active site topology with AroF, AroG and AroH but no similarities at the inhibitor binding site. Complementation of a triple E. coli knockout strain ( ΔaroF, ΔaroG, ΔaroH ) with c1220 restores its ability to grow in minimal media. On the other hand, the E. coli CFT073 knock out strain Δc1220 remains capable of growth in minimal media. Our results confirm that C1220 is indeed a DAHPS, but suggest it is not part of the shikimate pathway. NIH AI‐061531 funded.