Thioredoxin, the Processivity Factor, Sequesters an Exposed Cysteine in the Thumb Domain of Bacteriophage T7 DNA Polymerase

Tran, Ngoc Quang; Lee, Seung-Joo; Akabayov, Barak; Johnson, Donald E.; Richardson, Charles C.

doi:10.1074/jbc.m112.409235

Cited by 12 publications

(9 citation statements)

References 39 publications

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“…Previously, it has been suggested that the interaction of Trx with g5p and ASK1 target proteins is critically dependent on the redox state of Trx, despite being independent of Trx oxido-reductase function (9,20). However, later studies have proposed alternative models possibly involving the oxidoreductase function of Trx in regulation of these proteins (36,37). In light of these studies and others, the absolute dependence of these interactions on the Trx redox-state may need to be reevaluated using a direct solution-based measurement of noncovalent interaction between Trx and these target proteins.…”

Section: Discussionmentioning

confidence: 99%

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: Discussionmentioning

confidence: 99%

A universal entropy-driven mechanism for thioredoxin–target recognition

Palde

Carroll

2015

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

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“…The T7 DNA polymerase also uses an asymmetric ring to bind to DNA, yet its finger domains cannot fully wrap around it. An additional processivity factor (thioredoxin) helps to stretch a finger, thus allowing full enclosure 11. Therefore, as described for T4 polymerase, closing of the ring also happens with T7 polymerase, where thioredoxin regulates processivity.…”

Section: Processive Enzymes In Naturementioning

confidence: 99%

Processive Catalysis

et al. 2014

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Nature's enzymes are an ongoing source of inspiration for scientists. The complex processes behind their selectivity and efficiency is slowly being unraveled, and these findings have spawned many biomimetic catalysts. However, nearly all focus on the conversion of small molecular substrates. Nature itself is replete with inventive catalytic systems which modify, replicate, or decompose entire polymers, often in a processive fashion. Such processivity can, for example, enhance the rate of catalysis by clamping to the polymer substrate, which imparts a large effective molarity. Reviewed herein are the various strategies for processivity in nature's arsenal and their properties. An overview of what has been achieved by chemists aiming to mimic one of nature's greatest tricks is also included.

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“…Auch die T7‐DNA‐Polymerase nutzt einen unsymmetrischen Ring, um DNA zu binden, allerdings können die Fingerdomänen diese nicht vollständig umschließen. Dies ermöglicht ein zusätzlicher Prozessivitätsfaktor (Thioredoxin), der dabei hilft, die Finger zu strecken 11. Wie für die T4‐Polymerase wird der Ring also auch für die T7‐Polymerase geschlossen.…”

Section: Prozessive Enzyme In Der Naturunclassified

Prozessive Katalyse

et al. 2014

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Die Enzyme natürlicher Systeme haben Naturwissenschaftler schon immer inspiriert. Die komplexen Prozesse, auf denen ihre Selektivität und Effizienz beruhen, kommen langsam ans Tageslicht. Viele biomimetische Katalysatoren wurden nach ihrem Vorbild entworfen, allerdings liegt fast immer der Schwerpunkt auf der Umwandlung niedermolekularer Substrate. Die Natur hingegen kennt viele katalytische Systeme, die ganze Polymere modifizieren, replizieren oder abbauen, und das oft in prozessiver Weise. Beispielsweise kann das Anklammern des Katalysators an das Polymersubstrat zu einer solchen Prozessivität führen und, als Folge einer großen effektiven Molarität, die Geschwindigkeit der Katalyse erhöhen. Dieser Kurzaufsatz stellt verschiedene Strategien der Prozessivität in natürlichen Systemen und deren Eigenschaften vor. Zudem werden die Erfolge beschrieben, die Chemiker bei der Nachahmung eines der großartigsten Tricks der Natur bislang verbuchen konnten.

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Thioredoxin, the Processivity Factor, Sequesters an Exposed Cysteine in the Thumb Domain of Bacteriophage T7 DNA Polymerase

Cited by 12 publications

References 39 publications

A universal entropy-driven mechanism for thioredoxin–target recognition

A universal entropy-driven mechanism for thioredoxin–target recognition

Processive Catalysis

Prozessive Katalyse

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