PDBsum entry 4jh4

Transferase

PDB id: 4jh4

Contents

Protein chains

138 a.a.

Ligands

FCN ×2

Metals

_NI ×2

Waters ×142

PDB id:

4jh4

Name:

Transferase

Title:

Crystal structure of fosb from bacillus cereus with nickel and fosfomycin

Structure:

Metallothiol transferase fosb. Chain: a, b. Synonym: fosfomycin resistance protein. Engineered: yes

Source:

Bacillus cereus. Organism_taxid: 222523. Strain: atcc 10987. Gene: fosb, bce_2111. Expressed in: escherichia coli. Expression_system_taxid: 562

Resolution:

1.90Å R-factor: 0.175 R-free: 0.216

Authors:

M.K.Thompson,J.Harp,M.E.Keithly,K.Jagessar,P.D.Cook,R.N.Armstrong

Key ref:

M.K.Thompson et al. (2013). Structural and chemical aspects of resistance to the antibiotic fosfomycin conferred by FosB from Bacillus cereus. Biochemistry, 52, 7350-7362. PubMed id: 24004181 DOI: 10.1021/bi4009648

Date:

04-Mar-13 Release date: 02-Oct-13

Protein chains

Q739M9  (FOSB_BACC1) -  Metallothiol transferase FosB from Bacillus cereus (strain ATCC 10987 / NRS 248)

Seq: 138 a.a.

Struc: 138 a.a.

Enzyme reactions

• Enzyme class: E.C.2.5.1.- - ?????

DOI no: 10.1021/bi4009648

Biochemistry 52:7350-7362 (2013)

PubMed id: 24004181

Structural and chemical aspects of resistance to the antibiotic fosfomycin conferred by FosB from Bacillus cereus.

M.K.Thompson, M.E.Keithly, J.Harp, P.D.Cook, K.L.Jagessar, G.A.Sulikowski, R.N.Armstrong.

ABSTRACT

The fosfomycin resistance enzymes, FosB, from Gram-positive organisms, are M(2+)-dependent thiol tranferases that catalyze nucleophilic addition of either l-cysteine (l-Cys) or bacillithiol (BSH) to the antibiotic, resulting in a modified compound with no bacteriacidal properties. Here we report the structural and functional characterization of FosB from Bacillus cereus (FosB(Bc)). The overall structure of FosB(Bc), at 1.27 Å resolution, reveals that the enzyme belongs to the vicinal oxygen chelate (VOC) superfamily. Crystal structures of FosB(Bc) cocrystallized with fosfomycin and a variety of divalent metals, including Ni(2+), Mn(2+), Co(2+), and Zn(2+), indicate that the antibiotic coordinates to the active site metal center in an orientation similar to that found in the structurally homologous manganese-dependent fosfomycin resistance enzyme, FosA. Surface analysis of the FosB(Bc) structures show a well-defined binding pocket and an access channel to C1 of fosfomycin, the carbon to which nucleophilic addition of the thiol occurs. The pocket and access channel are appropriate in size and shape to accommodate l-Cys or BSH. Further investigation of the structures revealed that the fosfomycin molecule, anchored by the metal, is surrounded by a cage of amino acids that hold the antibiotic in an orientation such that C1 is centered at the end of the solvent channel, positioning the compound for direct nucleophilic attack by the thiol substrate. In addition, the structures of FosB(Bc) in complex with the l-Cys-fosfomycin product (1.55 Å resolution) and in complex with the bacillithiol-fosfomycin product (1.77 Å resolution) coordinated to a Mn(2+) metal in the active site have been determined. The l-Cys moiety of either product is located in the solvent channel, where the thiol has added to the backside of fosfomycin C1 located at the end of the channel. Concomitant kinetic analyses of FosB(Bc) indicated that the enzyme has a preference for BSH over l-Cys when activated by Mn(2+) and is inhibited by Zn(2+). The fact that Zn(2+) is an inhibitor of FosB(Bc) was used to obtain a ternary complex structure of the enzyme with both fosfomycin and l-Cys bound.