Specific Function of the Met-Tyr-Trp Adduct Radical and Residues Arg-418 and Asp-137 in the Atypical Catalase Reaction of Catalase-Peroxidase KatG

Zhao, Xiangbo; Khajo, Abdelahad; Jarrett, S. J.; Suárez, Javier; Levitsky, Yan; Burger, Richard M.; Jarzęcki, Andrzej A.; Magliozzo, Richard S.

doi:10.1074/jbc.m112.401208

Cited by 24 publications

(49 citation statements)

References 35 publications

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“…On the basis of these results, we were able to put forward a model of the enzymatic activity in which we postulated the formation of two Cpd I species, one of which is capable of peroxidatic activity, the other of catalytic activity. Importantly, the radical adduct species has been characterized spectroscopically very recently [ 110 ]. The peculiar properties of the M-Y-W adduct, specifically its low ionization potential when Tyr238 is unprotonated, have been proposed to be responsible for O 2 activation by KatG [ 111 ].…”

Section: Qm/mm Applications To the Study Of Enzymatic Reactivity Amentioning

confidence: 99%

QM/MM Molecular Dynamics Studies of Metal Binding Proteins

Vidossich

Magistrato

2014

Biomolecules

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Mixed quantum-classical (quantum mechanical/molecular mechanical (QM/MM)) simulations have strongly contributed to providing insights into the understanding of several structural and mechanistic aspects of biological molecules. They played a particularly important role in metal binding proteins, where the electronic effects of transition metals have to be explicitly taken into account for the correct representation of the underlying biochemical process. In this review, after a brief description of the basic concepts of the QM/MM method, we provide an overview of its capabilities using selected examples taken from our work. Specifically, we will focus on heme peroxidases, metallo-β-lactamases, α-synuclein and ligase ribozymes to show how this approach is capable of describing the catalytic and/or structural role played by transition (Fe, Zn or Cu) and main group (Mg) metals. Applications will reveal how metal ions influence the formation and reduction of high redox intermediates in catalytic cycles and enhance drug metabolism, amyloidogenic aggregate formation and nucleic acid synthesis. In turn, it will become manifest that the protein frame directs and modulates the properties and reactivity of the metal ions.

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Section: Qm/mm Applications To the Study Of Enzymatic Reactivity Amentioning

confidence: 99%

QM/MM Molecular Dynamics Studies of Metal Binding Proteins

Vidossich

Magistrato

2014

Biomolecules

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“…The X-ray structures revealed that KatGs possess unique covalent bonds formed among the side chains of three distal residues, Met-Tyr-Trp, which are located on the distal side of the haem active site. Mutagenesis studies confirmed that the Met-Tyr-Trp cross-link is required for catalatic activity (Regelsberger et al, 2000;Jakopitsch et al, 2004;Ghiladi et al, 2005;Kapetanaki et al, 2007;Zhao et al, 2010Zhao et al, , 2013. These structures have provided many insights into the structure and function of KatGs.…”

Section: Introductionmentioning

confidence: 82%

The 2.2 Å resolution structure of the catalase-peroxidase KatG fromSynechococcus elongatusPCC7942

Kamachi¹,

Wada²,

Tamoi³

et al. 2014

Acta Cryst Sect F

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The crystal structure of catalase-peroxidase from Synechococcus elongatus PCC7942 (SeKatG) was solved by molecular replacement and refined to an Rwork of 16.8% and an Rfree of 20.6% at 2.2 Å resolution. The asymmetric unit consisted of only one subunit of the catalase-peroxidase molecule, including a protoporphyrin IX haem moiety and two sodium ions. A typical KatG covalent adduct was formed, Met248-Tyr222-Trp94, which is a key structural element for catalase activity. The crystallographic equivalent subunit was created by a twofold symmetry operation to form the functional dimer. The overall structure of the dimer was quite similar to other KatGs. One sodium ion was located close to the proximal Trp314. The location and configuration of the proximal cation site were very similar to those of typical peroxidases such as ascorbate peroxidase. These features may provide a structural basis for the behaviour of the radical localization/delocalization during the course of the enzymatic reaction.

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“…tion, whereas the in conformation is connected with reduction of the MYW radical (39,44,45,49,53). Interestingly, a recent computational study suggests that Arg-418 facilitates the rotation of the Tyr and Trp aromatic rings with respect to one another, helping enable reduction of the MYW radical by the Fe III -O 2 .…”

Section: Proximal Tryptophan and Inactivation Of Katg Catalasementioning

confidence: 99%

“…At pH 6.5, corresponding roughly to the optimum pH for catalase activity, this arginine equally populates both conformational states (48,49). Substitution of Arg-418 with Leu, Ala, or Asn, but not Lys, sharply diminishes the catalase activity of KatG (39,49,50,52), and as has been recently shown with Magnaporthe grisea extracellular KatG, it eliminates the pH dependence of catalase activity (52). The mechanism by which Arg-418 facilitates catalatic turnover is still under investigation.…”

mentioning

confidence: 90%

Mutual synergy between catalase and peroxidase activities of the bifunctional enzyme KatG is facilitated by electron hole-hopping within the enzyme

Njuma

Davis

Ndontsa

et al. 2017

Journal of Biological Chemistry

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KatG is a bifunctional, heme-dependent enzyme in the front-line defense of numerous bacterial and fungal pathogens against HO-induced oxidative damage from host immune responses. Contrary to the expectation that catalase and peroxidase activities should be mutually antagonistic, peroxidatic electron donors (PxEDs) enhance KatG catalase activity. Here, we establish the mechanism of synergistic cooperation between these activities. We show that at low pH values KatG can fully convert HO to O and HO only if a PxED is present in the reaction mixture. Stopped-flow spectroscopy results indicated rapid initial rates of HO disproportionation slowing concomitantly with the accumulation of ferryl-like heme states. These states very slowly returned to resting ( ferric) enzyme, indicating that they represented catalase-inactive intermediates. We also show that an active-site tryptophan, Trp-321, participates in off-pathway electron transfer. A W321F variant in which the proximal tryptophan was replaced with a non-oxidizable phenylalanine exhibited higher catalase activity and less accumulation of off-pathway heme intermediates. Finally, rapid freeze-quench EPR experiments indicated that both WT and W321F KatG produce the same methionine-tyrosine-tryptophan (MYW) cofactor radical intermediate at the earliest reaction time points and that Trp-321 is the preferred site of off-catalase protein oxidation in the native enzyme. Of note, PxEDs did not affect the formation of the MYW cofactor radical but could reduce non-productive protein-based radical species that accumulate during reaction with HO Our results suggest that catalase-inactive intermediates accumulate because of off-mechanism oxidation, primarily of Trp-321, and PxEDs stimulate KatG catalase activity by preventing the accumulation of inactive intermediates.

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Specific Function of the Met-Tyr-Trp Adduct Radical and Residues Arg-418 and Asp-137 in the Atypical Catalase Reaction of Catalase-Peroxidase KatG

Cited by 24 publications

References 35 publications

QM/MM Molecular Dynamics Studies of Metal Binding Proteins

QM/MM Molecular Dynamics Studies of Metal Binding Proteins

The 2.2 Å resolution structure of the catalase-peroxidase KatG fromSynechococcus elongatusPCC7942

Mutual synergy between catalase and peroxidase activities of the bifunctional enzyme KatG is facilitated by electron hole-hopping within the enzyme

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