The crystal structure of augmenter of liver regeneration: A mammalian FAD‐dependent sulfhydryl oxidase

Wu, Chao‐Yi; Dailey, Tamara A.; Dailey, Harry A.; Wang, Bi-Cheng; Rose, John P.

doi:10.1110/ps.0238103

Cited by 104 publications

(105 citation statements)

References 27 publications

(28 reference statements)

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“…The monomer (short ALR) has mw of about 15 kDa while the cDNA for native ALR encodes a protein with mw of about 22 kDa [6,7]. The crystal structure [30] and the FAD-linked sulfhydryl oxidase and cytochrome c reductase activities of ALR [31] were deduced based on the assumption that it is present as a dimer of the short ALR. Unlike the rat and mouse ALR monomers, each 15 kDa subunit of human ALR contains two additional nonconserved free cysteine residues (C74 and C85) [31].…”

Section: Discussionmentioning

confidence: 99%

Augmenter of liver regeneration: An important intracellular survival factor for hepatocytes

Thirunavukkarasu

Wang

Harvey

et al. 2008

Journal of Hepatology

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Background/Aims-Augmenter of liver regeneration (ALR), a protein synthesized and stored in hepatocytes, is associated with mitochondria, and possesses sulfhydryl oxidase and cytochrome c reductase activities. We sought to determine the effects of ALR depletion in hepatocytes by antisense oligonucleotide transfection.Methods-Rat hepatocytes in primary culture were transfected with antisense oligonucleotide for ALR mRNA (ALR-AS) or scrambled oligonucleotide. Various analyses were performed at times up to 24 h after transfection.Results-Treatment with ALR-AS caused a decrease in ALR mRNA, cellular depletion of ALR protein primarily from mitochondria, and decreased viability. Flow cytometric analysis of ALR-AStransfected hepatocytes stained with annexin-V cy3 and 7-aminoactinomycin D revealed apoptosis as the predominant cause of death up to 6 h; incubation beyond this time resulted in necrosis in addition to apoptosis. ALR-AS-transfection caused release of mitochondrial cytochrome c, activation of caspase-3, profound reduction in the ATP content, and cellular release of LDH. Inhibition of caspase-3 inhibited the early phase of ALR-AS-induced death but not the late phase that included ALR and LDH release.Conclusions-These results suggest that ALR is critically important for the survival of hepatocytes by its association with mitochondria and regulation of ATP synthesis. KeywordsAugmenter of liver regeneration; Antisense; Hepatocytes; Apoptosis; Necrosis ☆ The authors who have taken part in the research of this paper declared that they do not have a relationship with the manufacturers of the materials involved either in the past or present and they did not receive funding from the manufacturers to carry out their research.

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Section: Discussionmentioning

confidence: 99%

Augmenter of liver regeneration: An important intracellular survival factor for hepatocytes

Thirunavukkarasu

Wang

Harvey

et al. 2008

Journal of Hepatology

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“…Erv2p has Lys-78 and FAD nearby Cys-124 (34); the Lys-78 N OH 2 is only 2.96 Å away from a carbonyl O 2 atom of the isoalloxazine ring. The equivalent residue is Arg in Erv-like domains of human and rat augmenter-of-liver-regeneration proteins (35,36). Furthermore, some flavoenzymes that contain an ERV͞ALR domain exhibit prominent thiolate-to-flavin CT bands (37,38).…”

Section: Do Quinone-and Flavin-dependent Disulfide Oxidoreductases Shmentioning

confidence: 99%

Critical role of a thiolate-quinone charge transfer complex and its adduct form in de novo disulfide bond generation by DsbB

Inaba

Takahashi

Ito

et al. 2005

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

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Recent studies have revealed numerous examples in which oxidation and reduction of cysteines in proteins are integrated into specific cascades of biological regulatory systems. In general, these reactions proceed as thiol-disulfide exchange events. However, it is not exactly understood how a disulfide bond is created de novo. DsbB, an Escherichia coli plasma membrane protein, is one of the enzymes that create a new disulfide bond within itself and in DsbA, the direct catalyst of protein disulfide bond formation in the periplasmic space. DsbB is associated with a cofactor, either ubiquinone or menaquinone, as a source of an oxidizing equivalent. The DsbB-bound quinone undergoes transition to a pink ( max, Ϸ500 nm, ubiquinone) or violet ( max, Ϸ550 nm, menaquinone)-colored state during the course of the DsbB enzymatic reaction. Here we show that not only the thiolate form of Cys-44 previously suggested but also Arg-48 in the ␣-helical arrangement is essential for the quinone transition. Quantum chemical simulations indicate that proper positioning of thiolate anion and ubiquinone in conjunction with positively charged guanidinium moiety of arginine allows the formation of a thiolate-ubiquinone charge transfer complex with absorption peaks at Ϸ500 nm as well as a cysteinylquinone covalent adduct. We propose that the charge transfer state leads to the transition state adduct that accepts a nucleophilic attack from another cysteine to generate a disulfide bond de novo. A similar mechanism is conceivable for a class of eukaryotic dithiol oxidases having a FAD cofactor.FAD ͉ ubiquinone ͉ DsbA

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“…The ERV/ALR proteins and their larger cousins in the QSOX family all contain a diminutive helix-rich flavin binding domain first reported for yeast Erv2p by Fass and coworkers (6) and for rat ALR by Rose and colleagues (4). Subunit A of the Erv2p homodimer is shown in the foreground of Figure 1.…”

mentioning

confidence: 90%

Erv2p: Characterization of the Redox Behavior of a Yeast Sulfhydryl Oxidase

2007

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The FAD prosthetic group of the ERV/ALR family of sulfhydryl oxidases is housed at the mouth of a 4-helix bundle and communicates with a pair of juxtaposed cysteine residues that form the proximal redox active disulfide. Most of these enzymes have one or more additional distal disulfide redox centers that facilitate the transfer of reducing equivalents from the dithiol substrates of these oxidases to the isoalloxazine ring where the reaction with molecular oxygen occurs. The present study examines yeast Erv2p and compares the redox behavior of this ER luminal protein with the augmenter of liver regeneration, a sulfhydryl oxidase of the mitochondrial intermembrane space, and a larger protein containing the ERV/ALR domain, quiescin-sulfhydryl oxidase (QSOX). Dithionite and photochemical reductions of Erv2p show full reduction of the flavin cofactor after the addition of 4-electrons with a mid-point potential of -200 mV at pH 7.5. A charge-transfer complex between a proximal thiolate and the oxidized flavin is not observed in Erv2p consistent with a distribution of reducing equivalents over the flavin and distal disulfide redox centers. Upon coordination with Zn 2+ , full reduction of Erv2p requires 6-electrons. Zn 2+ also strongly inhibits Erv2p when assayed using tris(2-carboxyethyl)phosphine (TCEP) as the reducing substrate of the oxidase. In contrast to QSOX, Erv2p shows a comparatively low turnover with a range of small thiol substrates, with reduced Escherichia coli thioredoxin and with unfolded proteins. Rapid reaction studies confirm that reduction of the flavin center of Erv2p is rate-limiting during turnover with molecular oxygen. This comparison of the redox properties between members of the ERV/ALR family of sulfhydryl oxidases provides insights into their likely roles in oxidative protein folding.Over the last decade a number of eukaryotic flavin-dependent sulfhydryl oxidases have been described that catalyze the net generation of disulfide bonds:They include: yeast ERV1 (essential for respiration and vegetative growth) (1) and its mammalian counterpart augmenter of liver regeneration, ALR, (2-4); yeast Erv2p (5-7); an Arabidopsis homolog of these proteins (8,9); yeast and its vertebrate orthologs Ero1α and Ero1β (15,16); and finally larger multidomain sulfhydryl oxidases, containing an ERV/ALR module fused to a redox active thioredoxin domain, that are found principally in multicellular organisms (17)(18)(19)(20) The ERV/ALR proteins and their larger cousins in the QSOX family all contain a diminutive helix-rich flavin binding domain first reported for yeast Erv2p by Fass and coworkers (6) and for rat ALR by Rose and colleagues (4). Subunit A of the Erv2p homodimer is shown in the foreground of Figure 1. The isoalloxazine ring is inserted at the end of a bundle of four helices in the A subunit with its C2/N3 region exposed to solvent (6). The proximal disulfide C121-124 is placed so that the sulfur of C124 is adjacent (3.4 Å) to the C 4a position of the flavin. This locus is consistent with i...

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The crystal structure of augmenter of liver regeneration: A mammalian FAD‐dependent sulfhydryl oxidase

Cited by 104 publications

References 27 publications

Augmenter of liver regeneration: An important intracellular survival factor for hepatocytes

Augmenter of liver regeneration: An important intracellular survival factor for hepatocytes

Critical role of a thiolate-quinone charge transfer complex and its adduct form in de novo disulfide bond generation by DsbB

Erv2p: Characterization of the Redox Behavior of a Yeast Sulfhydryl Oxidase

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