Mechanism for the Hydrolysis of a Sulfur-Sulfur Bond Based on the Crystal Structure of the Thiosulfohydrolase SoxB

Sauvé, Véronique; Roversi, Pietro; Leath, K.J.; Garman, Elspeth F.; Antrobus, Robin; Lea, Susan M.; Berks, Ben C.

doi:10.1074/jbc.m109.002709

Cited by 40 publications

(47 citation statements)

References 56 publications

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“…The trithionate hydrolase activity of SoxB decreased in the presence of the metal chelator EDTA, but was increased when the assay mix was supplemented with Mn 2+ ions, consistent with catalysis by the active site metal ions. The previously reported SoxB-thiosulfate cocrystal structure suggests that active site residue Arg416 is involved in substrate binding and transition-state stabilization (16). In agreement with this hypothesis, we found that an Arg416Gly variant had undetectable trithionate hydrolase activity (Table 1).…”

Section: Soxy-s-s-sosupporting

confidence: 81%

“…The carboxymethyl group (-CH 2 -CO 2 − ) has physicochemical similarity to S-thiosulfonate. However, amidating this species produces a functional group (-CH 2 -CONH 2 ) that, like SoxY C151S Z, would be unable to provide the bidentate ligation of the active site manganese ions exhibited by the substrate analog thiosulfate (16). SoxY(Ac)Z exhibits an endothermic enthalpy change on interaction with SoxB that is identical to that measured for SoxY(SSO 3 − )Z (Fig.…”

Section: Soxy-s-s-sosupporting

confidence: 50%

“…SoxB contains a pair of Mn(II) ions at the active site to which the sulfone group (-SO 3 − ) of the nonhydrolyzable substrate analog thiosulfate ( − S-SO 3 − ) is seen to bind in a cocrystal (16,19). The trithionate hydrolase activity of SoxB decreased in the presence of the metal chelator EDTA, but was increased when the assay mix was supplemented with Mn 2+ ions, consistent with catalysis by the active site metal ions.…”

Section: Soxy-s-s-somentioning

confidence: 97%

“…Trp175 stabilizes the sulfane group of the substrate analog thiosulfate in the previously determined SoxB-thiosulfate complex structure (16) and so was inferred to be close to the carrier arm Cys sulfur atom in the native SoxB-SoxYZ complex. To provide a leaving group in the disulfide bond-forming reaction, we used the S-thiosulfonate derivative of the partner SoxYZ protein (Reaction 3).…”

Section: Soxy-s-s-somentioning

confidence: 99%

“…Thus, SoxYZ carries a range of chemical species and must interact with multiple partner enzymes. Structures of the SoxYZ partner enzymes show that their active site access channels are wide enough to permit carrier arm-bound substrates to reach the catalytic groups (15)(16)(17). The proteins of the Sox pathway do not copurify with each other from cell extracts.…”

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confidence: 99%

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Structural basis for specificity and promiscuity in a carrier protein/enzyme system from the sulfur cycle

Grabarczyk

Chappell

Johnson

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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The bacterial Sox (sulfur oxidation) pathway is an important route for the oxidation of inorganic sulfur compounds. Intermediates in the Sox pathway are covalently attached to the heterodimeric carrier protein SoxYZ through conjugation to a cysteine on a protein swinging arm. We have investigated how the carrier protein shuttles intermediates between the enzymes of the Sox pathway using the interaction between SoxYZ and the enzyme SoxB as our model. The carrier protein and enzyme interact only weakly, but we have trapped their complex by using a "suicide enzyme" strategy in which an engineered cysteine in the SoxB active site forms a disulfide bond with the incoming carrier arm cysteine. The structure of this trapped complex, together with calorimetric data, identifies sites of protein-protein interaction both at the entrance to the enzyme active site tunnel and at a second, distal, site. We find that the enzyme distinguishes between the substrate and product forms of the carrier protein through differences in their interaction kinetics and deduce that this behavior arises from substrate-specific stabilization of a conformational change in the enzyme active site. Our analysis also suggests how the carrier arm-bound substrate group is able to outcompete the adjacent C-terminal carboxylate of the carrier arm for binding to the active site metal ions. We infer that similar principles underlie carrier protein interactions with other enzymes of the Sox pathway.swinging arm | thiosulfate oxidation | Sox system

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Section: Soxy-s-s-sosupporting

confidence: 81%

Section: Soxy-s-s-sosupporting

confidence: 50%

Section: Soxy-s-s-somentioning

confidence: 97%

Section: Soxy-s-s-somentioning

confidence: 99%

mentioning

confidence: 99%

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Structural basis for specificity and promiscuity in a carrier protein/enzyme system from the sulfur cycle

Grabarczyk

Chappell

Johnson

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

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Cytoplasmic sulfur trafficking in sulfur‐oxidizing prokaryotes

Dahl

2015

IUBMB Life

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Persulfide groups are chemically versatile and participate in a wide array of biochemical pathways. Although it is well documented that persulfurated proteins supply a number of important and elaborate biosynthetic pathways with sulfane sulfur, it is far less acknowledged that the enzymatic generation of persulfidic sulfur, the successive transfer of sulfur as a persulfide between multiple proteins, and the oxidation of sulfane sulfur in protein-bound form are also essential steps during dissimilatory sulfur oxidation in bacteria and archaea. Here, the currently available information on sulfur trafficking in sulfur oxidizing prokaryotes is reviewed, and the idea is discussed that sulfur is always presented to cytoplasmic oxidizing enzymes in a protein-bound form, thus preventing the occurrence of free sulfide inside of the prokaryotic cell. Thus, sulfur trafficking emerges as a central element in sulfuroxidizing pathways, and TusA homologous proteins appear to be central and common elements in these processes. V C 2015 IUBMB Life, 67(4): [268][269][270][271][272][273][274] 2015

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Reaction mechanism of tetrathionate hydrolysis based on the crystal structure of tetrathionate hydrolase from Acidithiobacillus ferrooxidans

et al. 2020

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Tetrathionate hydrolase (4THase) plays an important role in dissimilatory sulfur oxidation in the acidophilic iron-and sulfur-oxidizing bacterium Acidithiobacillus ferrooxidans. The structure of recombinant 4THase from A. ferrooxidans (Af-Tth) was determined by X-ray crystallography to a resolution of 1.95 Å. Af-Tth is a homodimer, and its monomer structure exhibits an eight-bladed β-propeller motif. Two insertion loops participate in dimerization, and one loop forms a cavity with the β-propeller region. We observed unexplained electron densities in this cavity of the substrate-soaked structure. The anomalous difference map generated using diffraction data collected at a wavelength of 1.9 Å indicated the presence of polymerized sulfur atoms. Asp325, a highly conserved residue among 4THases, was located near the polymerized sulfur atoms. 4THase activity was completely abolished in the sitespecific Af-Tth D325N variant, suggesting that Asp325 plays a crucial role in the first step of tetrathionate hydrolysis. Considering that the Af-Tth reaction occurs only under acidic pH, Asp325 acts as an acid for the tetrathionate hydrolysis reaction. The polymerized sulfur atoms in the active site cavity may represent the intermediate product in the subsequent step.

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Mechanism for the Hydrolysis of a Sulfur-Sulfur Bond Based on the Crystal Structure of the Thiosulfohydrolase SoxB

Cited by 40 publications

References 56 publications

Structural basis for specificity and promiscuity in a carrier protein/enzyme system from the sulfur cycle

Structural basis for specificity and promiscuity in a carrier protein/enzyme system from the sulfur cycle

Cytoplasmic sulfur trafficking in sulfur‐oxidizing prokaryotes

Reaction mechanism of tetrathionate hydrolysis based on the crystal structure of tetrathionate hydrolase from Acidithiobacillus ferrooxidans

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