How many ways to craft a cofactor?

Klinman, Judith P.

doi:10.1073/pnas.011602498

Cited by 38 publications

(22 citation statements)

References 34 publications

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“…Inadequate characterization of cofactor biosynthesis is not a problem that is unique to CDO, however, as the mechanisms by which most protein-derived cofactors are formed remain poorly understood (12). Galactose oxidase, however, forms a cross-linked cofactor that is identical to CDO, and the process by which it is synthesized has been examined.…”

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confidence: 99%

Synthesis of Amino Acid Cofactor in Cysteine Dioxygenase Is Regulated by Substrate and Represents a Novel Post-translational Regulation of Activity

Dominy

Hwang

Guo

et al. 2008

Journal of Biological Chemistry

110

169

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Cysteine dioxygenase (CDO) catalyzes the conversion of cysteine to cysteinesulfinic acid and is important in the regulation of intracellular cysteine levels in mammals and in the provision of oxidized cysteine metabolites such as sulfate and taurine. Several crystal structure studies of mammalian CDO have shown that there is a cross-linked cofactor present in the active site of the enzyme. The cofactor consists of a thioether bond between the ␥-sulfur of residue cysteine 93 and the aromatic side chain of residue tyrosine 157. The exact requirements for cofactor synthesis and the contribution of the cofactor to the catalytic activity of the enzyme have yet to be fully described. In this study, therefore, we explored the factors necessary for cofactor biogenesis in vitro and in vivo and examined what effect cofactor formation had on activity in vitro. Like other cross-linked cofactorcontaining enzymes, formation of the Cys-Tyr cofactor in CDO required a transition metal cofactor (Fe 2؉ ) and O 2 . Unlike other enzymes, however, biogenesis was also strictly dependent upon the presence of substrate. Cofactor formation was also appreciably slower than the rates reported for other enzymes and, indeed, took hundreds of catalytic turnover cycles to occur. In the absence of the Cys-Tyr cofactor, CDO possessed appreciable catalytic activity, suggesting that the cofactor was not essential for catalysis. Nevertheless, at physiologically relevant cysteine concentrations, cofactor formation increased CDO catalytic efficiency by ϳ10-fold. Overall, the regulation of Cys-Tyr cofactor formation in CDO by ambient cysteine levels represents an unusual form of substrate-mediated feed-forward activation of enzyme activity with important physiological consequences.Recent biochemical and crystallographic studies have revealed that some enzymes contain unusual modifications to the amino acid residues residing within their active sites. Also known as amino acid-derived cofactors, these altered residues represent a new and exciting area for research in the field of protein post-translational modifications. Unlike other posttranslational modifications, which are made by attaching extrinsic molecules onto target proteins through reactions that are specifically catalyzed by third party enzymes, amino acid cofactors are generated directly from the amino acids within the proteins that contain them and are required for the production of fully competent enzymes (1, 2). From a biological perspective, amino acid-derived cofactors are significant because they can create novel structural motifs within the enzyme active site as well as alter the chemical properties of the unmodified parent amino acid residues and thus expand the otherwise limited range of catalytic reactions in which the common amino acids can participate.One recent addition to the list of enzymes known to contain an amino acid cofactor is cysteine dioxygenase (CDO).3 CDO is an iron (Fe 2ϩ )-dependent thiol dioxygenase that uses molecular oxygen to oxidize the sulfhydryl group of cys...

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confidence: 99%

Synthesis of Amino Acid Cofactor in Cysteine Dioxygenase Is Regulated by Substrate and Represents a Novel Post-translational Regulation of Activity

Dominy

Hwang

Guo

et al. 2008

Journal of Biological Chemistry

110

169

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“…The enzymes utilize a trihydroxyphenylalanine quinone (TPQ) cofactor derived from posttranslational modification of an active site tyrosine residue in a reaction that requires the presence of copper(II) and O 2 . 54 Once formed the TPQ cofactor is sequentially reduced by primary amines and reoxidized by O 2 in kinetically independent processes.…”

Section: Copper Amine Oxidasesmentioning

confidence: 99%

Heavy Atom Isotope Effects as Probes of Small Molecule Activation

Roth

2010

Physical Inorganic Chemistry

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“…Each subunit contains three internal disulfide bonds (Cys4-Cys62, Cys17-Cys65, Cys37-Cys101) together with an unusual lysine tyrosyl quinone (LTQ) linkage between the side chains of Lys31 and Tyr2 ( Figure 4). Posttranslational modifications of this kind have previously been described as cofactors or intermediates in (copper) lysyl oxidase enzyme mechanisms, [4][5][6][7][8][9] but the crystallographic structure reported herein constitutes its first visualization as a stable entity in a native protein. Unlike the lysyl oxidase system, the LTQ group in Pl-RSF-1 is largely buried from solvent ( Figure S5 in the Supporting Information) and has no coordinating metal.…”

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confidence: 99%

“…[2,20] They are also rich sourcesofnovelproteins.Theworkpresentedherein indicates that P1-RSF-1 is a new member of the quinoprotein family, [5] and our demonstration of unusual cross-links in a naturally occurring protein, particularly the unforeseen 4-residue bis(LTQ) chromophore, adds further to the growing family of posttranslational modifications that are difficult to predict from DNA sequence data alone. [4] …”

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confidence: 99%

“…Blue proteins are relatively rare in biology, and the chromophore of Pl-RSF-1 has little similarity with the polyenes, carotenoids, or porphyrins found in more familiar blue/green proteins. However, LTQ and related compounds are implicated as cofactors in protein cross-linking for matrix stabilization (connective tissues [5,6,8] or dopamine-based protein adhesives and cements from mussels and other marine organisms [18,19]) and there are plausible mechanisms extending such schemes to obtain …”

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confidence: 99%

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Unusual Chromophore and Cross‐Links in Ranasmurfin: A Blue Protein from the Foam Nests of a Tropical Frog

Oke¹,

Ching

Carter³

et al. 2008

Angew Chem Int Ed

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Ranasmurfin is an unusual blue protein isolated from the nests of a Malaysian tree frog, Polypedates leucomystax, [1] showing the rich chemical diversity displayed by biomolecular foams. Many species of tropical frogs use foams to protect delicate eggs and developing embryos against environmental challenges. These nests act as miniature ecosystems containing a spectrum of novel proteins and other macromolecules with functions related to foam stabilization and adhesion, resistance to microbial degradation, predation, or dehydration, providing a biocompatible environment for embryonic development.Thisworkformspartofourwiderstudyofthe intriguing physical and chemical properties of biofoams as unusual examples of biological soft matter. [2] P. leucomystax is an abundant Rhacophorid frog that is widespread in Malaysia and surrounding regions of South-East Asia. During mating, the female produces a protein-rich fluid that she, together with the attending male, whips up into a sticky foam nest incorporating the fertilized eggs (see the Supporting Information Figure S1). The nests are usually attached to vegetation or other structures overhanging water into which the tadpoles fall when fully developed (usually after 3-4 days in the wild).[3] These nests exhibit a variety of pigmentation, usually pale creamy white/orange when first † † To whom correspondence should be addressed. naismith@st-and.ac.uk, phone 44-1334-463792, fax 44-1334-467229 alanc@chem.gla.ac.uk, phone 44-141-330 5278, fax 44-141-330 (Figure1 ), which are consistent with the presence of two ionizable moieties with pKa values of 6 and 9, and the color fades slowly (overnight) upon treatment with ethylenediaminetetraacetic acid (EDTA) and dithiothreitol (DTT; Figure S9 in the Supporting Information). The chromophore is bleached rapidly (seconds) by low concentrations (0.25 mm) of N-bromosuccinimide (NBS, Figure 1).Ranasmurfin, purified from natural material, crystallizes readily as deep blue crystals that diffract well, allowing protein structure determination to 1.16 A resolution (Figures 2 and 3; see the Supporting Information for crystallographic details). Initial X-ray diffraction experiments indicated the presence of a heavy metal in the protein, which was subsequently identified as zinc by X-ray fluorescence of the crystals (Ref.[1] and Supporting Information). Zinc was also the dominant metal detected by ICP-OES experiments on purified protein solutions (ca. 1.2 mol Zn/26 kDa). The presence of a heavy metal facilitated the structure determination. The phases from the Zn atom extended to 1.6 A and gave a well-resolved electron-density map in which two molecules per asymmetric unit could be traced. Phases were extended to 1.16 A by solvent flattening and twofold averaging. This resolution was sufficient to identify most amino acids in the polypeptide chain, even in the absence of the complete protein or encoding cDNA sequence, and minor ambiguities were resolved by comparison with peptide sequences determined denovo by mass spectrometry. T...

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How many ways to craft a cofactor?

Cited by 38 publications

References 34 publications

Synthesis of Amino Acid Cofactor in Cysteine Dioxygenase Is Regulated by Substrate and Represents a Novel Post-translational Regulation of Activity

Synthesis of Amino Acid Cofactor in Cysteine Dioxygenase Is Regulated by Substrate and Represents a Novel Post-translational Regulation of Activity

Heavy Atom Isotope Effects as Probes of Small Molecule Activation

Unusual Chromophore and Cross‐Links in Ranasmurfin: A Blue Protein from the Foam Nests of a Tropical Frog

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