A Conserved Mechanism for Sulfonucleotide Reduction

Carroll, Kate S.; Gao, Hong; Chen, Huiyi; Stout, C.D.; Leary, Julie A.; Bertozzi, Carolyn R.

doi:10.1371/journal.pbio.0030250

Cited by 76 publications

(198 citation statements)

References 51 publications

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“…Extracellular Trx1 reduces HIV envelop protein gp120 (10) and TG2, an enzyme implicated in celiac disease (11). Bacterial Trx reduces SRs with a crucial role in sulfur assimilation (8). Fig.…”

Section: Favorable Entropy Drives Noncovalent Association Of Trx and mentioning

confidence: 99%

“…PAPR catalytic mechanism. The sulfur atom of PAPS undergoes nucleophilic attack by C239 of PAPR resulting in formation of E-Cys-S-SO 3 − intermediate, followed by release of SO 3 2-vis-à-vis Trx-mediated thiol-disulfide exchange (8).…”

Section: Favorable Entropy Drives Noncovalent Association Of Trx and mentioning

confidence: 99%

“…Next, we asked whether the entropy-driven recognition mechanism is unique to Trx•PAPR interaction or whether it might be extended to other Trx•SR interactions. We explored this possibility with adenosine-5′-phosphosulfate reductases (APSRs), which are members of the SR family and are known to undergo substrate-induced conformational changes akin to PAPR (8,31). We first evaluated C32A Trx binding to Mycobacterium tuberculosis APSR (MtAPSR).…”

Section: Conformational Restriction Of Oxidized Papr Is Essential Formentioning

confidence: 99%

“…For example, Trx activates methionine sulfoxide reductases (MSrs), enzymes involved in protein repair and aging (6), and peroxidoxins (Prxs), a family of enzymes that converts H 2 O 2 to water (7). Bacterial Trx is essential to the catalytic cycle of sulfonucleotide reductases (SRs), enzymes involved in reductive sulfur assimilation and validated targets for antibacterial drugs (8). In humans, cytosolic Trx (Trx1) inhibits the activity of proapoptotic protein, ASK-1 and the tumor suppressor protein, PTEN (4,9).…”

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confidence: 99%

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A universal entropy-driven mechanism for thioredoxin–target recognition

Palde

Carroll

2015

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

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Cysteine residues in cytosolic proteins are maintained in their reduced state, but can undergo oxidation owing to posttranslational modification during redox signaling or under conditions of oxidative stress. In large part, the reduction of oxidized protein cysteines is mediated by a small 12-kDa thiol oxidoreductase, thioredoxin (Trx). Trx provides reducing equivalents for central metabolic enzymes and is implicated in redox regulation of a wide number of target proteins, including transcription factors. Despite its importance in cellular redox homeostasis, the precise mechanism by which Trx recognizes target proteins, especially in the absence of any apparent signature binding sequence or motif, remains unknown. Knowledge of the forces associated with the molecular recognition that governs Trx-protein interactions is fundamental to our understanding of target specificity. To gain insight into Trx-target recognition, we have thermodynamically characterized the noncovalent interactions between Trx and target proteins before S-S reduction using isothermal titration calorimetry (ITC). Our findings indicate that Trx recognizes the oxidized form of its target proteins with exquisite selectivity, compared with their reduced counterparts. Furthermore, we show that recognition is dependent on the conformational restriction inherent to oxidized targets. Significantly, the thermodynamic signatures for multiple Trx targets reveal favorable entropic contributions as the major recognition force dictating these proteinprotein interactions. Taken together, our data afford significant new insight into the molecular forces responsible for Trx-target recognition and should aid the design of new strategies for thiol oxidoreductase inhibition.thioredoxin | redox regulation | protein-protein interactions | entropy | oxidative stress

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Section: Favorable Entropy Drives Noncovalent Association Of Trx and mentioning

confidence: 99%

Section: Favorable Entropy Drives Noncovalent Association Of Trx and mentioning

confidence: 99%

Section: Conformational Restriction Of Oxidized Papr Is Essential Formentioning

confidence: 99%

mentioning

confidence: 99%

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A universal entropy-driven mechanism for thioredoxin–target recognition

Palde

Carroll

2015

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

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“…Other interactions with the iron-sulfur cluster involve Thr-87 and Trp-246. In the active site, the phosphosulfate group of APS is positioned opposite the [4Fe-4S] cluster, and although no atoms intervene, the sulfate moiety is not in direct contact with the [4Fe-4S] cluster.Given the unusual Cys-Cys dyad coordination and its requirement for catalytic activity, defining the function and properties of the iron-sulfur cluster in APR has generated considerable interest (1,5,7,16,17). Most proteins containing [4Fe-4S] clusters are redox-active (18 -21); however, the [4Fe-4S] 2ϩ cluster in APR does not undergo redox changes during the catalytic cycle (1).…”

mentioning

confidence: 99%

Spectroscopic Studies on the [4Fe-4S] Cluster in Adenosine 5′-Phosphosulfate Reductase from Mycobacterium tuberculosis

Bhave¹,

Hong

Lee³

et al. 2011

Journal of Biological Chemistry

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Mycobacterium tuberculosis adenosine 5-phosphosulfate reductase (MtAPR) is an iron-sulfur protein and a validated target to develop new antitubercular agents, particularly for the treatment of latent infection. The enzyme harbors a [4Fe-4S]2؉ cluster that is coordinated by four cysteinyl ligands, two of which are adjacent in the amino acid sequence. The ironsulfur cluster is essential for catalysis; however, the precise role of the [4Fe-4S] cluster in APR remains unknown. Progress in this area has been hampered by the failure to generate a paramagnetic state of the [4Fe-4S] cluster that can be studied by electron paramagnetic resonance spectroscopy. Herein, we overcome this limitation and report the EPR spectra of MtAPR in the [4Fe-4S] ؉ state. The EPR signal is rhombic and consists of two overlapping S ‫؍‬ 1 ⁄ 2 species. Substrate binding to MtAPR led to a marked increase in the intensity and resolution of the EPR signal and to minor shifts in principle g values that were not observed among a panel of substrate analogs, including adenosine 5-diphosphate. Using site-directed mutagenesis, in conjunction with kinetic and EPR studies, we have also identified an essential role for the active site residue Lys-144, whose side chain interacts with both the iron-sulfur cluster and the sulfate group of adenosine 5-phosphosulfate. The implications of these findings are discussed with respect to the role of the iron-sulfur cluster in the catalytic mechanism of APR.In bacteria and plants, activation of inorganic sulfur is required for de novo biosynthesis of cysteine. To this end, the metabolic assimilation of sulfate from the environment proceeds via adenosine 5Ј-phosphosulfate (APS) 2 or 3Ј-phosphoadenosine-5Ј-phosphosulfate (PAPS) (1). These intermediates are produced by the action of ATP-sulfurylase (EC 2.7.7.4), which condenses sulfate and ATP to form APS (2, 3), and by APS kinase (EC 2.7.1.25), which produces PAPS from ATP and APS (4).APS and PAPS are reduced by enzymes in the reductive branch of the sulfate assimilation pathway, producing sulfite and AMP or adenosine 3Ј,5Ј-diphosphate (Scheme 1). These enzymes can be subdivided into two groups according to their substrate preference: the APS reductases (APR) and the PAPS reductases (PAPR) (EC 1.8.99.4). Functional and structural studies have been used to investigate the chemical reaction mechanism of APR and PAPR enzymes (1,(5)(6)(7)(8). The mechanism involves nucleophilic attack by the active site cysteine on the sulfur atom of APS or PAPS to form an enzyme S-sulfocysteine intermediate, which is cleaved by thiol-disulfide exchange with thioredoxin or glutaredoxin (Fig. 1). The sulfite product is then reduced to sulfide by sulfite reductase (EC 1.8.7.1) and utilized to synthesize cysteine and other essential sulfur-containing biomolecules (9). In the human pathogen Mycobacterium tuberculosis, APR is a validated target against the latent phase of infection (10).Only a 3Ј-phosphate group distinguishes PAPS from APS. Accordingly, APR and PAPR have nearly identical three...

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Electronic Structure, Bonding, Spin Coupling, and Energetics of Polynuclear Iron–Sulfur Clusters – A Broken Symmetry Density Functional Theory Perspective

Hopmann

Pelmenschikov

et al. 2015

Spin States in Biochemistry and Inorganic Chemistry

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A Conserved Mechanism for Sulfonucleotide Reduction

Cited by 76 publications

References 51 publications

A universal entropy-driven mechanism for thioredoxin–target recognition

A universal entropy-driven mechanism for thioredoxin–target recognition

Spectroscopic Studies on the [4Fe-4S] Cluster in Adenosine 5′-Phosphosulfate Reductase from Mycobacterium tuberculosis

Electronic Structure, Bonding, Spin Coupling, and Energetics of Polynuclear Iron–Sulfur Clusters – A Broken Symmetry Density Functional Theory Perspective

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