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Lane LA, Nadeau OW, Carlson GM, Robinson CV. Mass spectrometry reveals differences in stability and subunit interactions between activated and nonactivated conformers of the (αβγδ)4 phosphorylase kinase complex. Mol Cell Proteomics 2012; 11:1768-76. [PMID: 22964223 PMCID: PMC3518106 DOI: 10.1074/mcp.m112.021394] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Phosphorylase kinase (PhK), a 1.3 MDa enzyme complex that regulates glycogenolysis, is composed of four copies each of four distinct subunits (α, β, γ, and δ). The catalytic protein kinase subunit within this complex is γ, and its activity is regulated by the three remaining subunits, which are targeted by allosteric activators from neuronal, metabolic, and hormonal signaling pathways. The regulation of activity of the PhK complex from skeletal muscle has been studied extensively; however, considerably less is known about the interactions among its subunits, particularly within the non-activated versus activated forms of the complex. Here, nanoelectrospray mass spectrometry and partial denaturation were used to disrupt PhK, and subunit dissociation patterns of non-activated and phospho-activated (autophosphorylation) conformers were compared. In so doing, we have established a network of subunit contacts that complements and extends prior evidence of subunit interactions obtained from chemical crosslinking, and these subunit interactions have been modeled for both conformers within the context of a known three-dimensional structure of PhK solved by cryoelectron microscopy. Our analyses show that the network of contacts among subunits differs significantly between the nonactivated and phospho-activated conformers of PhK, with the latter revealing new interprotomeric contact patterns for the β subunit, the predominant subunit responsible for PhK's activation by phosphorylation. Partial disruption of the phosphorylated conformer yields several novel subcomplexes containing multiple β subunits, arguing for their self-association within the activated complex. Evidence for the theoretical αβγδ protomeric subcomplex, which has been sought but not previously observed, was also derived from the phospho-activated complex. In addition to changes in subunit interaction patterns upon phospho-activation, mass spectrometry revealed a large change in the overall stability of the complex, with the phospho-activated conformer being more labile, in concordance with previous hypotheses on the mechanism of allosteric activation of PhK through perturbation of its inhibitory quaternary structure.
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Affiliation(s)
- Laura A Lane
- Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, UK
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2
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Nadeau OW, Wyckoff GJ, Paschall JE, Artigues A, Sage J, Villar MT, Carlson GM. CrossSearch, a user-friendly search engine for detecting chemically cross-linked peptides in conjugated proteins. Mol Cell Proteomics 2008; 7:739-49. [PMID: 18281724 DOI: 10.1074/mcp.m800020-mcp200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Chemical cross-linking and high resolution MS have been integrated successfully to capture protein interactions and provide low resolution structural data for proteins that are refractive to analyses by NMR or crystallography. Despite the versatility of these combined techniques, the array of products that is generated from the cross-linking and proteolytic digestion of proteins is immense and generally requires the use of labeling strategies and/or data base search algorithms to distinguish actual cross-linked peptides from the many side products of cross-linking. Most strategies reported to date have focused on the analysis of small cross-linked protein complexes (<60 kDa) because the number of potential forms of covalently modified peptides increases dramatically with the number of peptides generated from the digestion of such complexes. We report herein the development of a user-friendly search engine, CrossSearch, that provides the foundation for an overarching strategy to detect cross-linked peptides from the digests of large (>or=170-kDa) cross-linked proteins, i.e. conjugates. Our strategy combines the use of a low excess of cross-linker, data base searching, and Fourier transform ion cyclotron resonance MS to experimentally minimize and theoretically cull the side products of cross-linking. Using this strategy, the (alpha beta gamma delta)(4) phosphorylase kinase model complex was cross-linked to form with high specificity a 170-kDa betagamma conjugate in which we identified residues involved in the intramolecular cross-linking of the 125-kDa beta subunit between its regulatory N terminus and its C terminus. This finding provides an explanation for previously published homodimeric two-hybrid interactions of the beta subunit and suggests a dynamic structural role for the regulatory N terminus of that subunit. The results offer proof of concept for the CrossSearch strategy for analyzing conjugates and are the first to reveal a tertiary structural element of either homologous alpha or beta regulatory subunit of phosphorylase kinase.
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Affiliation(s)
- Owen W Nadeau
- Department of Biochemistry and Molecular Biology, University of Kansas Medical Center, Kansas City, Kansas 66160, USA
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3
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Nadeau OW, Anderson DW, Yang Q, Artigues A, Paschall JE, Wyckoff GJ, McClintock JL, Carlson GM. Evidence for the location of the allosteric activation switch in the multisubunit phosphorylase kinase complex from mass spectrometric identification of chemically crosslinked peptides. J Mol Biol 2006; 365:1429-45. [PMID: 17123541 PMCID: PMC1852525 DOI: 10.1016/j.jmb.2006.10.061] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2006] [Revised: 10/10/2006] [Accepted: 10/18/2006] [Indexed: 10/24/2022]
Abstract
Phosphorylase kinase (PhK), an (alphabetagammadelta)(4) complex, regulates glycogenolysis. Its activity, catalyzed by the gamma subunit, is tightly controlled by phosphorylation and activators acting through allosteric sites on its regulatory alpha, beta and delta subunits. Activation by phosphorylation is predominantly mediated by the regulatory beta subunit, which undergoes a conformational change that is structurally linked with the gamma subunit and that is characterized by the ability of a short chemical crosslinker to form beta-beta dimers. To determine potential regions of interaction of the beta and gamma subunits, we have used chemical crosslinking and two-hybrid screening. The beta and gamma subunits were crosslinked to each other in phosphorylated PhK, and crosslinked peptides from digests were identified by Fourier transform mass spectrometry, beginning with a search engine developed "in house" that generates a hypothetical list of crosslinked peptides. A conjugate between beta and gamma that was verified by MS/MS corresponded to crosslinking between K303 in the C-terminal regulatory domain of gamma (gammaCRD) and R18 in the N-terminal regulatory region of beta (beta1-31), which contains the phosphorylatable serines 11 and 26. A synthetic peptide corresponding to residues 1-22 of beta inhibited the crosslinking between beta and gamma, and was itself crosslinked to K303 of gamma. In two-hybrid screening, the beta1-31 region controlled beta subunit self-interactions, in that they were favored by truncation of this region or by mutation of the phosphorylatable serines 11 and 26, thus providing structural evidence for a phosphorylation-dependent subunit communication network in the PhK complex involving at least these two regulatory regions of the beta and gamma subunits. The sum of our results considered together with previous findings implicates the gammaCRD as being an allosteric activation switch in PhK that interacts with all three of the enzyme's regulatory subunits and is proximal to the active site cleft.
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Affiliation(s)
- Owen W. Nadeau
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66209
| | - David W. Anderson
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66209
| | - Qing Yang
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66209
| | - Antonio Artigues
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66209
| | - Justin E. Paschall
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 66211
| | - Gerald J. Wyckoff
- Division of Molecular Biology and Biochemistry, School of Biological Sciences, University of Missouri-Kansas City, Kansas City, Missouri 66211
| | - Jennifer L. McClintock
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66209
| | - Gerald M. Carlson
- Department of Biochemistry and Molecular Biology, The University of Kansas Medical Center, Kansas City, Kansas 66209
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4
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Saravanamuthu A, Vickers TJ, Bond CS, Peterson MR, Hunter WN, Fairlamb AH. Two interacting binding sites for quinacrine derivatives in the active site of trypanothione reductase: a template for drug design. J Biol Chem 2004; 279:29493-500. [PMID: 15102853 PMCID: PMC3491871 DOI: 10.1074/jbc.m403187200] [Citation(s) in RCA: 85] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Trypanothione reductase is a key enzyme in the trypanothione-based redox metabolism of pathogenic trypanosomes. Because this system is absent in humans, being replaced with glutathione and glutathione reductase, it offers a target for selective inhibition. The rational design of potent inhibitors requires accurate structures of enzyme-inhibitor complexes, but this is lacking for trypanothione reductase. We therefore used quinacrine mustard, an alkylating derivative of the competitive inhibitor quinacrine, to probe the active site of this dimeric flavoprotein. Quinacrine mustard irreversibly inactivates Trypanosoma cruzi trypanothione reductase, but not human glutathione reductase, in a time-dependent manner with a stoichiometry of two inhibitors bound per monomer. The rate of inactivation is dependent upon the oxidation state of trypanothione reductase, with the NADPH-reduced form being inactivated significantly faster than the oxidized form. Inactivation is slowed by clomipramine and a melarsen oxide-trypanothione adduct (both are competitive inhibitors) but accelerated by quinacrine. The structure of the trypanothione reductase-quinacrine mustard adduct was determined to 2.7 A, revealing two molecules of inhibitor bound in the trypanothione-binding site. The acridine moieties interact with each other through pi-stacking effects, and one acridine interacts in a similar fashion with a tryptophan residue. These interactions provide a molecular explanation for the differing effects of clomipramine and quinacrine on inactivation by quinacrine mustard. Synergism with quinacrine occurs as a result of these planar acridines being able to stack together in the active site cleft, thereby gaining an increased number of binding interactions, whereas antagonism occurs with nonplanar molecules, such as clomipramine, where stacking is not possible.
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Affiliation(s)
- Ahilan Saravanamuthu
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, U.K
| | - Tim J. Vickers
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, U.K
| | - Charles S. Bond
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, U.K
| | - Mark R. Peterson
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, U.K
| | - William N. Hunter
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, U.K
| | - Alan H. Fairlamb
- Division of Biological Chemistry and Molecular Microbiology, The Wellcome Trust Biocentre, School of Life Sciences, University of Dundee, Dundee, DD1 5EH, U.K
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5
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Nadeau OW, Sacks DB, Carlson GM. Differential affinity cross-linking of phosphorylase kinase conformers by the geometric isomers of phenylenedimaleimide. J Biol Chem 1997; 272:26196-201. [PMID: 9334187 DOI: 10.1074/jbc.272.42.26196] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Phosphorylase b kinase (PbK) from skeletal muscle is a highly regulated oligomer consisting of four copies of four distinct subunits (alphabetagamma)delta4. The gamma subunit is catalytic, and the remaining subunits are regulatory. To characterize effector-induced changes in the quaternary structure of the enzyme, we utilized the ortho-, meta, and para-isomers of phenylenedimaleimide (PDM), which in addition to having different geometries, also vary 2.5-fold in their cross-linking spans. Even at concentrations equivalent to the alphabetagammadelta protomers of PbK, all three isomers caused specific, rapid, and extensive cross-linking of the holoenzyme to form primarily alphabeta dimers, plus smaller amounts of betagammagamma and alphagammagamma trimers. The formation of these three conjugates was nearly totally inhibited by a 10-fold molar excess over PDM of N-(o- and p-tolyl)succinimide, which are chemically inert structural analogs of PDM. This inhibition suggests that PbK has binding sites for PDM and that PDM acts as an affinity cross-linker in binding to these sites prior to forming cross-linked conjugates. The largest effect on cross-linking in progressing from o- to p-PDM was on the alphagammagamma trimer, which is preferentially formed by the p-isomer. Activation of the enzyme by either phosphorylation or the allosteric activators ADP and GDP resulted in large increases in the amount of alphagammagamma formed, small increases in betagammagamma, and little change in alphabeta. When cross-linked in the presence of the reversibly activating nucleoside diphosphates, PbK remained activated after their removal, indicating that cross-linking had locked it in the active conformation. Our results provide direct evidence for perturbations in the interactions of the catalytic gamma subunit with the regulatory alpha and beta subunits upon activation of PbK.
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Affiliation(s)
- O W Nadeau
- Department of Biochemistry, College of Medicine, the University of Tennessee, Memphis, Tennessee 38163, USA
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6
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Yang SJ, Jiang SS, Tzeng CM, Kuo SY, Hung SH, Pan RL. Involvement of tyrosine residue in the inhibition of plant vacuolar H(+)-pyrophosphatase by tetranitromethane. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1294:89-97. [PMID: 8639720 DOI: 10.1016/0167-4838(96)00005-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Plant vacuolar vesicles contain a novel H(+)-translocating pyrophosphatase (H(+)-PPase, EC 3.6.1.1). Modification of tonoplast vesicles and purified vacuolar H(+)-PPase from etiolated mung bean seedlings with tetranitromethane (TNM) resulted in a progressive decline in H(+)-translocating pyrophosphatase activity. The half-maximal inhibition was brought about by 0.6, 1.0, and 0.8 mM TNM for purified and membrane-bound H(+)-PPases, and its associated proton translocation, respectively. The maximal inhibition of vacuolar H(+)-PPase by TNM occurred at a pH value above 8. Loss of activity of purified H(+)-pyrophosphatase followed pseudo-first order rate kinetics, yielding a first-order rate constant (k2) of 0.039 s(-1) and a steady-state dissociation constant of inactivation (Ki) of 0.02 mM. Covalent modification of vacuolar H(+)-PPase by TNM increased Km value of the enzyme for its substrate without a significant effect on Vmax. Double logarithmic plots of the pseudo-first order rate constant (kobs) versus TNM concentration exhibited a slope of 0.88, suggesting that at least one tyrosine residue was involved in the inactivation of H(+)-PPase enzymatic activity. Further spectrophotometric measurements of the nitrated H(+)-pyrophosphatase indicated that TNM could modify approximately two tyrosine residues/subunit of the enzyme. However, Tsou's analysis revealed that only one of those modified tyrosine residues directly participated in the inhibition of enzymatic activity of vacuolar H(+)-PPase. The physiological substrate, i.e., dimagnesium pyrophosphate, provided substantial protection against inactivation by TNM. Moreover, NEM pretreatment of the enzyme decreased the number of subsequent nitration of vacuolar H(+)-PPase. Taken together, we suggest that vacuolar H(+)-pyrophosphatase contains a substrate-protectable tyrosine residue conferring to the inhibition of its activity and this tyrosine residue may be located in a domain sensitive to the modification of Cys-634 by NEM.
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Affiliation(s)
- S J Yang
- Institute of Radiation Biology, College of Nuclear Science, National Tsing Hua University, Taiwan, Republic of China
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7
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Cao H, Preiss J. Evidence for essential arginine residues at the active sites of maize branching enzymes. JOURNAL OF PROTEIN CHEMISTRY 1996; 15:291-304. [PMID: 8804577 DOI: 10.1007/bf01887118] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Alignment of 23 branching enzyme (BE) amino acid sequences from various species showed conservation of two arginine residues. Phenylglyoxal (PGO) was used to investigate the involvement of arginine residues of maize BEI and BEII in catalysis. BE was significantly inactivated by PGO in triethanolamine buffer at pH 8.5. The inactivation followed a time- and concentration-dependent manner and showed pseudo first-order kinetics. Slopes of 0.73 (BEI) and 1.05 (BEII) were obtained from double log plots of the observed rates of inactivation against the concentrations of PGO, suggesting that loss of BE activity results from as few as one arginine residue modified by PGO. BE inactivation was positively correlated with [14C]PGO incorporation into BE protein and was considerably protected by amylose and/or amylopectin, suggesting that the modified arginine residue may be involved in substrate binding or located near the substrate-binding sites of maize branching enzymes I and II.
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Affiliation(s)
- H Cao
- Department of Biochemistry, Michigan State University, East Lansing 48824, USA
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8
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Bettey M, Smith JA. Dicarboxylate transport at the vacuolar membrane of the CAM plant Kalanchoë daigremontiana: sensitivity to protein-modifying and sulphydryl reagents. BIOCHIMICA ET BIOPHYSICA ACTA 1993; 1152:270-9. [PMID: 8218327 DOI: 10.1016/0005-2736(93)90258-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Malate is widespread as a charge-balancing anion in plant vacuoles and plays a central role in nocturnal CO2 assimilation in crassulacean acid metabolism (CAM). To characterize the malate transport system at the vacuolar membrane of CAM plants, tonoplast vesicles were prepared from leaf mesophyll cells of the crassulacean plant Kalanchoë daigremontiana. Dicarboxylate uptake, assayed by a membrane-filtration method using [14C]malate or [14C]succinate, displayed saturation kinetics with apparent Km values of 4.0 mM (malate) and 1.8 mM (succinate); competition experiments indicated that both anions were transported by the same system. Dicarboxylate uptake was stimulated severalfold by activation of the tonoplast H(+)-ATPase or H(+)-PPiase, an effect inhibitable by ionophore. Passive (non-energized) dicarboxylate uptake was sensitive to the sulphydryl reagents N-ethylmaleimide and p-chloromercuribenzene sulphonate, as well as to a range of protein modifiers. In particular, inhibition by pyridoxal phosphate was completely substrate-protectable, and that by phenylglyoxal partially so, thus implicating at least one lysine residue and perhaps also an arginine residue in the substrate-recognition site of the transport protein. The involvement of one or more critical lysine residue was supported by analysis of the initial phase of inhibition by pyridoxal phosphate: this showed pseudo-first-order kinetics with a reaction order of 1.03 +/- 0.13 and a Kd for substrate protection close to the apparent Km for dicarboxylate uptake.
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Affiliation(s)
- M Bettey
- Department of Plant Sciences, University of Oxford, UK
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9
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Lee HJ, Chiou SH, Chang GG. Inactivation of the endogenous argininosuccinate lyase activity of duck delta-crystallin by modification of an essential histidine residue with diethyl pyrocarbonate. Biochem J 1993; 293 ( Pt 2):537-44. [PMID: 8343133 PMCID: PMC1134395 DOI: 10.1042/bj2930537] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The argininosuccinate lyase activity of duck delta-crystallin was inactivated by diethyl pyrocarbonate at 0 degrees C and pH 7.5. The inactivation followed pseudo-first-order kinetics after appropriate correction for the decomposition of the reagent during the modification period. The plot of the observed pseudo-first-order rate constant versus diethyl pyrocarbonate concentration in the range of 0.17-1.7 mM was linear and went through the origin with a second-order rate constant of 1.45 +/- 0.1 M-1.s-1. The double-logarithmic plot was also linear, with slope of 1.13, which suggested a 1:1 stoichiometry for the reaction between diethyl pyrocarbonate and delta-crystallin. L-Arginine, L-norvaline or L-citrulline protected the argininosuccinate lyase activity of delta-crystallin from diethyl pyrocarbonate inactivation. The dissociation constants for the delta-crystallin-L-arginine and delta-crystallin-L-citrulline binary complexes, determined by the protection experiments, were 4.2 +/- 0.2 and 0.12 +/- 0.04 mM respectively. Fumarate alone had no protective effect. However, fumarate plus L-arginine gave synergistic protection with a ligand binding interacting factor of 0.12 +/- 0.02. The double-protection data conformed to a random Uni Bi kinetic mechanism. Fluorescence-quenching studies indicated that the modified delta-crystallin had minimum, if any, conformational changes as compared with the native delta-crystallin. Inactivation of the enzyme activity was accompanied by an increasing absorbance at 240 nm of the protein. The absorption near 280 nm did not change. Treatment of the modified protein with hydroxylamine regenerated the enzyme activity to the original level. These results strongly indicated the modification of an essential histidine residue. Calculation from the 240 nm absorption changes indicated that only one histidine residue per subunit was modified by the reagent. This super-active histidine residue has a pKa value of approximately 6.8 and acts as a general acid-base catalyst in the enzyme reaction mechanism. Our experimental data are compatible with an E1cB mechanism [Raushel (1984) Arch. Biochem. Biophys. 232, 520-525] for the argininosuccinate lyase with the essential histidine residue close to the arginine-binding domain of delta-crystallin. L-Citrulline, after binding to this domain, might form an extra hydrogen bond with the essential histidine residue.
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Affiliation(s)
- H J Lee
- Department of Biochemistry, National Defense Medical Center, Taipei, Taiwan, Republic of China
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10
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Tzeng CM, Hsu LH, Pan RL. Inhibition of tonoplast ATPase from etiolated mung bean seedlings by fluorescein 5'-isothiocyanate. Biochem J 1992; 285 ( Pt 3):737-43. [PMID: 1386733 PMCID: PMC1132857 DOI: 10.1042/bj2850737] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Fluorescein 5'-isothiocyanate (FITC) was used to modify the lysine residue in the active site of tonoplast H(+)-ATPase from etiolated mung-bean (Vigna radiata L.) seedlings. FITC caused marked inactivation of the enzyme activities of both membrane-bound and soluble ATPase and its associated H+ translocation. The SDS/PAGE pattern revealed that the FITC-binding site was in the large (A) subunit of ATPase. Inhibition could be substantially prevented by its physiological substrate ATP, pyrophosphate and nucleotides in the decreasing order: ATP greater than pyrophosphate greater than ADP greater than AMP greater than GTP greater than CTP greater than UTP. The mode of inhibition by FITC was competitive with respect to ATP. Loss of ATPase activity followed pseudo-first-order kinetics with a Ki of 0.33 mM, a minimum inactivation half-time of 110 s, and a first-order rate constant of 0.244 s-1. A double-logarithmic plot of apparent rate constant versus FITC concentration gave a slope of 0.913, indicating that inactivation results from reaction of at least one lysine residue at the catalytic site of the large subunit. Labelling studies indicated that the incorporation of approx. 1 mol of FITC/mol of ATPase is sufficient to inhibit ATPase completely. The enhancement and blue shift of emission maxima of FITC after modification of ATPase indicated that the labelled lysine residue was located in a relatively hydrophobic domain.
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Affiliation(s)
- C M Tzeng
- Institute of Radiation Biology, College of Nuclear Sciences, National Tsing Hua University, Hsin Chu, Taiwan, Republic of China
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11
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Prat-Gay G, Wolosiuk R. Differential reactivity of chloroplast fructose-l,6-bisphosphatase to Woodward's reagent K and diethylpyrocarbonate. BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS 1989. [DOI: 10.1016/s0005-2728(89)80388-3] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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12
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Shani-Sekler M, Goldshleger R, Tal DM, Karlish SJ. Inactivation of Rb+ and Na+ occlusion on (Na+,K+)-ATPase by modification of carboxyl groups. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)77638-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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13
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Winberg JO, McKinley-McKee JS. Drosophila melanogaster alcohol dehydrogenase. Biochemical properties of the NAD+-plus-acetone-induced isoenzyme conversion. Biochem J 1988; 251:223-7. [PMID: 3134011 PMCID: PMC1148987 DOI: 10.1042/bj2510223] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The NAD+ + acetone-induced isoenzyme conversion of the Drosophila melanogaster AdhS alleloenzyme was studied. Absorption and fluorescence spectra as well as electrophoretic and kinetic methods show that the conversion process proceeds through three steps. Initially a binary enzyme-NAD+ complex is formed, followed by a ternary enzyme-NAD+-acetone complex with a KEO,Ac of 1.7 M. The last step is a rate-limiting irreversible process in which NAD+ and acetone are covalently linked to the enzyme. A Vm of 2.4 min-1 was obtained at pH 8.6.
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Affiliation(s)
- J O Winberg
- Biochemical Institute, University of Oslo, Blindern, Norway
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14
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King MM. Conformation-sensitive modification of the type II calmodulin-dependent protein kinase by phenylglyoxal. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)68848-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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15
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Malebrán LP, Cardemil E. The presence of functional arginine residues in phosphoenolpyruvate carboxykinase from Saccharomyces cerevisiae. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 915:385-92. [PMID: 3307926 DOI: 10.1016/0167-4838(87)90024-0] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Saccharomyces cerevisiae phosphoenolpyruvate carboxykinase (ATP:oxaloacetate carboxy-lyase (transphosphorylating), EC 4.1.1.49) is completely inactivated by phenylglyoxal and 2,3-butanedione in borate buffer at pH 8.4, with pseudo-first-order kinetics and a second-order rate constant of 144 min-1 X M-1 and 21.6 min-1 X M-1, respectively. Phosphoenolpyruvate, ADP and Mn2+ (alone or in combination) protect the enzyme against inactivation, suggesting that the modification occurs at or near to the substrate-binding site. Almost complete restoration of activity was obtained when a sample of 2,3-butanedione-inactivated enzyme was freed of excess modifier and borate ions, suggesting that only arginyl groups are modified. The changes in the rate of inactivation in the presence of substrates and Mn2+ were used to determine the dissociation constants for enzyme-ligand complexes, and values of 23 +/- 3 microM, 168 +/- 44 microM and 244 +/- 54 microM were found for the dissociation constants for the enzyme-Mn2+, enzyme-ADP and enzyme-phosphoenolpyruvate complexes, respectively. Based on kinetic data, it is shown that 1 mol of reagent must combine per enzyme active unit in order to inactivate the enzyme. Complete inactivation of the carboxykinase can be correlated with the incorporation of 3-4 mol [7-14C]phenylglyoxal per mol of enzyme subunit. Assuming a stoichiometry of 1:1 between phenylglyoxal incorporation and arginine modification, our results suggest that the modification of only two of the three to four reactive arginine residues per phosphoenolpyruvate carboxykinase subunit is responsible for inactivation.
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Affiliation(s)
- L P Malebrán
- Departamento de Química, Facultad de Ciencia, Universidad de Santiago de Chile
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16
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King MM, Heiny LP. Chemical modification of the calmodulin-stimulated phosphatase, calcineurin, by phenylglyoxal. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61014-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Igarashi P, Aronson PS. Covalent modification of the renal Na+/H+ exchanger by N,N'-dicyclohexylcarbodiimide. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(19)75866-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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King MM. Modification of the calmodulin-stimulated phosphatase, calcineurin, by sulfhydryl reagents. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(17)35625-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Ozer I. On the relationship between reaction order and stoichiometry in irreversible inhibition of enzymes. Arch Biochem Biophys 1986; 245:153-6. [PMID: 3947096 DOI: 10.1016/0003-9861(86)90199-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The relationship between reaction order and stoichiometry in inhibition of enzymes by potentially irreversible inhibitors is discussed. It is pointed out that in an overwhelming fraction of cases reported or imagined, the order in inhibitor concentration approximates one, regardless of actual stoichiometry. It follows that reaction order should not be employed as a reliable measure of the number of amino acid residues involved in the inactivation process.
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Rakitzis ET. Kinetics of protein modification reactions: interpretation of reaction order. ACTA ACUST UNITED AC 1986. [DOI: 10.1016/0304-5102(86)87058-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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