Accepted name: apo-salmochelin esterase
Reaction: (1) enterobactin + H2O = N-(2,3-dihydroxybenzoyl)-L-serine trimer
(2) triglucosyl-enterobactin + H2O = triglucosyl-(2,3-dihydroxybenzoylserine)3
(3) diglucosyl-enterobactin + H2O = diglucosyl-(2,3-dihydroxybenzoylserine)3
(4) monoglucosyl-enterobactin + H2O = monoglucosyl-(2,3-dihydroxybenzoylserine)3
Glossary: N-(2,3-dihydroxybenzoyl)-L-serine trimer = O-3-{O-3-[N-(2,3-dihydroxybenzoyl)-L-seryl]-N-(2,3-dihydroxybenzoyl)-L-seryl}-N-(2,3-dihydroxybenzoyl)-L-serine
diglucosyl-(2,3-dihydroxybenzoylserine)3 = salmochelin S2 = O-3-{O-3-[N-(2,3-dihydroxybenzoyl)-C-5-deoxy-β-D-glucosyl-L-seryl]-N-(2,3-dihydroxybenzoyl)-C-5-deoxy-β-D-glucosyl-L-seryl}-N-(2,3-dihydroxybenzoyl)-L-serine
enterobactin = N-(2,3-dihydroxybenzoyl)-O-[N-(2,3-dihydroxybenzoyl)-O-[N-(2,3-dihydroxybenzoyl)-L-seryl]-L-seryl]-L-serine-(3→1(3))-lactone
monoglucosyl-enterobactin = N-(2,3-dihydroxybenzoyl)-O-[N-(2,3-dihydroxybenzoyl)-O-[N-(5-β-D-glucopyranosyl-2,3-dihydroxybenzoyl)-L-seryl]-L-seryl]-L-serine-3→1(3)-lactone = mono-C-glucosyl-enterobactin = salmochelin MGE
diglucosyl-enterobactin = N-(2,3-dihydroxybenzoyl)-O-[N-(5-β-D-glucopyranosyl-2,3-dihydroxybenzoyl)-O-[N-(5-β-D-glucopyranosyl-2,3-dihydroxybenzoyl)-L-seryl]-L-seryl]-L-serine-(3→1(3))-lactone = salmochelin S4 = di-C-glucosyl-enterobactin
triglucosyl-enterobactin = N-(5-β-D-glucopyranosyl-2,3-dihydroxybenzoyl)-O-[N-(5-β-D-glucopyranosyl-2,3-dihydroxybenzoyl)-O-[N-(5-β-D-glucopyranosyl-2,3-dihydroxybenzoyl)-L-seryl]-L-seryl]-L-serine-(3→1(3))-lactone = tri-C-glucosyl-enterobactin = salmochelin TGE
Other name(s): iroE (gene name)
Systematic name: apo-salmochelin esterase
Comments: This bacterial enzyme is present in pathogenic Salmonella species, uropathogenic and avian pathogenic Escherichia coli strains, and certain Klebsiella strains. Unlike EC, ferric enterobactin esterase, which acts only on enterobactin, this enzyme can also act on the C-glucosylated forms known as salmochelins. Unlike EC, ferric salmochelin esterase (IroD), IroE prefers apo siderophores as substrates, and is assumed to act before the siderophores are exported out of the cell. It hydrolyses the trilactone only once, producing linearized trimers.
1.  Lin, H., Fischbach, M.A., Liu, D.R. and Walsh, C.T. In vitro characterization of salmochelin and enterobactin trilactone hydrolases IroD, IroE, and Fes. J. Am. Chem. Soc. 127 (2005) 11075–11084. [PMID: 16076215]
[EC created 2019]
Accepted name: iron(III)-enterobactin esterase
Reaction: iron(III)-enterobactin + 3 H2O = iron(III)-N-(2,3-dihydroxybenzoyl)-L-serine complex + 2 N-(2,3-dihydroxybenzoyl)-L-serine (overall reaction)
(1a) iron(III)-enterobactin + H2O = iron(III)-N-(2,3-dihydroxybenzoyl)-L-serine trimer complex
(1b) iron(III)-N-(2,3-dihydroxybenzoyl)-L-serine trimer complex + H2O = iron(III)-N-(2,3-dihydroxybenzoyl)-L-serine dimer complex + N-(2,3-dihydroxybenzoyl)-L-serine
(1c) iron(III)-N-(2,3-dihydroxybenzoyl)-L-serine dimer complex + H2O = iron(III)-N-(2,3-dihydroxybenzoyl)-L-serine complex + N-(2,3-dihydroxybenzoyl)-L-serine
Other name(s): fes (gene name); pfeE (gene name); enterochelin hydrolase; enterochelin esterase; ferric enterobactin esterase
Systematic name: iron(III)-enterobactin hydrolase
Comments: The enzyme, isolated from the bacterium Escherichia coli, allows the bacterium to grow in limited iron conditions. It can also act on enterobactin (with no complexed iron) and the aluminium(III) analogue of iron(III)-enterobactin. The trimer formed is further hydrolysed to form the dimer and the monomer.
1.  O'Brien, I.G., Cox, G.B. and Gibson, F. Enterochelin hydrolysis and iron metabolism in Escherichia coli. Biochim. Biophys. Acta 237 (1971) 537–549. [PMID: 4330269]
2.  Greenwood, K.T. and Luke, R.K. Enzymatic hydrolysis of enterochelin and its iron complex in Escherichia Coli K-12. Properties of enterochelin esterase. Biochim. Biophys. Acta 525 (1978) 209–218. [PMID: 150859]
3.  Pettis, G.S. and McIntosh, M.A. Molecular characterization of the Escherichia coli enterobactin cistron entF and coupled expression of entF and the fes gene. J. Bacteriol. 169 (1987) 4154–4162. [PMID: 3040679]
4.  Brickman, T.J. and McIntosh, M.A. Overexpression and purification of ferric enterobactin esterase from Escherichia coli. Demonstration of enzymatic hydrolysis of enterobactin and its iron complex. J. Biol. Chem. 267 (1992) 12350–12355. [PMID: 1534808]
5.  Winkelmann, G., Cansier, A., Beck, W. and Jung, G. HPLC separation of enterobactin and linear 2,3-dihydroxybenzoylserine derivatives: a study on mutants of Escherichia coli defective in regulation (fur), esterase (fes) and transport (fepA). Biometals 7 (1994) 149–154. [PMID: 8148617]
6.  Perraud, Q., Moynie, L., Gasser, V., Munier, M., Godet, J., Hoegy, F., Mely, Y., Mislin, G.LA., Naismith, J.H. and Schalk, I.J. A key role for the periplasmic PfeE esterase in iron acquisition via the siderophore enterobactin in Pseudomonas aeruginosa. ACS Chem. Biol. 13 (2018) 2603–2614. [PMID: 30086222]
[EC created 2019]