Search

The recent discovery of enzymes that convert methylated arginine residues in proteins to citrulline has catapulted arginine methylation into the attention of cell-signaling researchers. Long considered a rather static post-translational modification of marginal interest, it seems that arginine methylation has now joined the group of signaling pathways that operate via pairs of antagonistic enzymes. However, many questions remain unanswered, especially concerning the removal mechanism and its implication for the physiological role of arginine methylation. I propose that, in addition to the broadly discussed function as regulator of protein activity, arginine methylation might serve a second purpose: protection of arginine residues against attack by endogenous reactive dicarbonyl agents, such as methylglyoxal, which are natural by-products of normal metabolic pathways. Inefficient detoxification of these highly cytotoxic compounds results in inactivation of proteins that is causally linked to diabetes, cancer, neurodegenerative diseases and pathophysiologies of aging. This new concept of 'arginine protection' might have far-reaching implications for the development of drugs that exploit a natural protection mechanism for medical purposes.

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.tibs.2005.10.002 Byline: Frank O. Fackelmayer Abstract: The recent discovery of enzymes that convert methylated arginine residues in proteins to citrulline has catapulted arginine methylation into the attention of cell-signaling researchers. Long considered a rather static post-translational modification of marginal interest, it seems that arginine methylation has now joined the group of signaling pathways that operate via pairs of antagonistic enzymes. However, many questions remain unanswered, especially concerning the removal mechanism and its implication for the physiological role of arginine methylation. I propose that, in addition to the broadly discussed function as regulator of protein activity, arginine methylation might serve a second purpose: protection of arginine residues against attack by endogenous reactive dicarbonyl agents, such as methylglyoxal, which are natural by-products of normal metabolic pathways. Inefficient detoxification of these highly cytotoxic compounds results in inactivation of proteins that is causally linked to diabetes, cancer, neurodegenerative diseases and pathophysiologies of aging. This new concept of 'arginine protection' might have far-reaching implications for the development of drugs that exploit a natural protection mechanism for medical purposes. Author Affiliation: Department of Molecular Cell Biology, Heinrich-Pette-Institute, Martinistrasse 52, 20251 Hamburg, Germany

Bioaerosol mass spectrometry is being developed to analyze and identify biological aerosols in real time. Characteristic mass spectra from individual bacterial endospores of Bacillus subtilis var. niger were obtained in a bipolar aerosol time-of-flight mass spectrometer using a pulsed 266-nm laser for molecular desorption and ionization. Spectra from single spores collected at an average fluence of ~0.1 J/[cm.sup.2] frequently contain prominent peaks attributed to arginine, dipicolinic acid, and glutamic acid, but the shot-to-shot (spore-to-spore) variability in the data may make it difficult to consistently distinguish closely related Bacillus species with an automated routine. Fortunately, a study of the laser power dependence of the mass spectra reveals clear trends and a finite number of 'spectral types' that span most of the variability. This, we will show, indicates that a significant fraction of the variability must be attributed to fluence variations in the profile of the laser beam.

Research has been conducted on glutamate-126 and arginine-144 in Escherichia coli lactose permease. The role of these residues has been investigated via the study of their mutants, and the results demonstrate that glutamate-126 and arginine-144 are not important for sugar binding.

Research has been conducted on anticoagulant polysaccharide heparin binding plasma proteinase antithrombin. The study of Lys to Arg and Arg to Lys antithrombin substitutions has been carried out and the results demonstrate that Lys can replaced with Arg but Arg cannot be replaced with Lys.

Research has been conducted on Pseudomonas putida (S)-Mandelate dehydrogenase. The catalytic role of arginine residues Arg 165 and Arg 277 present in these enzymes and the importance of Arg165/Arg277 pair have been investigated and the results are reported.

Research has been conducted on the arginine substitutions in the DRY motif (aspartic acid, arginine and tyrosine). The effect of these substitutions in alpha (sub)1B -adrenergic receptors and angiotensin II type 1A receptors on their localization, signaling and desensitization has been studied and the results are presented.

Research has been conducted on the endothelial nitric oxide synthase heme domain. The results of the electron paramagnetic resonance and electron nuclear double resonance studies of the activated-oxygen reaction intermediates formed in this domain are presented.

Research has been conducted on the guanidines related to L-arginine. The oxidation of these compounds carried out via the recombinant NO-synthase II has produced a non-alpha-amino acid guanidine NO-synthase II substrate which acts as NO precursor.

Research has been conducted on the human genetic variant carbonic anhydrase I Michigan 1. The metal activation mechanism of this anhydrase and the catalytic mechanism of the CO (sub)2 hydration by alpha-carbonic anhydrases have been investigated and the results are presented.

Research has been conducted on the ferric endothelial nitric oxide synthase holoenzyme. The low-frequency resonance Raman spectra of this holoenzyme have been investigated in the presence of the L-arginine substrate and the results are reported.

Research has been conducted on the streptothricine F, a peptidyl nucleoside antibiotic. The timing and formation of the arginine-derived base streptolidine's incorporation during streptothricine F biosynthesis have been investigated and the details are reported.

The authors review the publications on physiological activity of nitric oxide synthases. The topics of interest include the enzymology of nitric oxide derived from nitric oxide synthase, superoxide generation and secondary free-radical formation by nitric oxide synthase.

Research has been conducted on the viral envelope protein gp120 and its human receptor CD4 complex formation. The structural features of the recombinant soluble CD4 have been investigated via the chemical modification of arginine residues with hydroxyphenylglyoxal, via the matrix-assisted laser desorption/ionization analysis and electrospray ionization mass spectrometry and the results are presented.

Research has been conducted on the nucleotide constraints. The binding constants for these substrates have been determined in the crystalline forms of the 3-phosphoglycerate kinase and the results indicate that the interaction between the 3-phosphoglycerate carboxylic group and a conserved arginine side chain has changed during the domain closure.

Research has been conducted on the bovine pituitary 20 S proteasome. The activities expressed by the X and Y subunits identified in this proteasome which cleave bonds after aromatic and branched chain amino acids and after acidic amino acids respectively have been investigated and the results indicate that arginine-rich histone H3-selective activation of the Y subunit could affect the proteasomal function in the nuclear compartment.

Research has been conducted on the technetium complex of dimethylglycyl-L-seryl-L-cys-teinyl(acm)-glycyl-L-threonyl-L-lysyl-L-prolyl-L-prolyl-L-arginine. The synthesis and characterization of this complex and its technetium and rhenium analogues have been performed and the results are reported.

Research has been conducted on the fumarate. The mechanism for the fumarate reduction in the respiratory fumarate reductases has been investigated and the results indicate that the X-ray substrate-bound structure forms of these enzymes are well positioned.

Research has been conducted on the proline-templated amino acids. The synthesis of the 3-substituted ornithine and arginine analogues protected for the Fmoc/Boc solid-phase synthesis is described.

Research has been conducted on the autophosphorylation of Tyr-1073 in the oncoprotein v-Fps's activation loop. The studies demonstrate that arginine countercharges for the activation loop phosphotyrosine are important for this autophosphorylation.

Research has been conducted on the arginine derivatives. The recognition of these derivatives via small tweezer molecules has been performed by understanding the nature and force of the noncovalent interactions involved in the binding process.

Research has been conducted on the acidic domain in nardilysin. The mouse acidic domain and the human nardilysin have been expressed as fusion proteins with glutathione S-transferase and the results indicate that nardilysin acidic domain can function as an autonomous domain.

Research has been conducted on the mitochondrial human type II arginase. The inhibition of this arginase by N (super)omega hydroxy-L-arginine and its analogue N (super)omega hydroxy-nor-L-arginine has been investigated and the results are discussed.

Research has been conducted on the peptide residue Arg-20 which activates parathyroid hormone receptor. The substitution of the Arg-20 with nonencoded amino acids and conformationally constrained analogues with side chains that mimick that of Arg has been conducted and the results are described.

Research has been conducted on the duck delta1 and delta2 crystallins. The comparison of all delta crystallin structures, the structure determinations of wild type duck delta 1 and delta 2 crystallins and the complete refinement of turkey delta 1 crystallin have been performed.

Research has been conducted on the insulin structure. The disulfide-forming pathway of a recombinant porcine insulin precursor has been investigated.

Research has been conducted on the Escherichia coli aspartate aminotransferase. The effect of substrate-binding arginine residues on the pK (sub)a value of the Schiff base formed between pyridoxal 5'-phosphate and Lys258 has been investigated.

Low-temperature optical absorption spectra indicate that there may be a tetrahydrobiopterin (BH4) redox role in both steps of nitric oxide synthase catalysis. The spectral changes that follow addition of oxygen to the reduced oxygenase domain of endothelial nitric oxide synthase (NOS) in the presence of various pteridines at -30 degrees Celsius were analyzed. Incomplete and slow formation of high-spin ferric heme with 4-amino-BH4 was seen and suggests a structural basis for inhibition of NOS activity by this pteridine.

Pseudomonas putida and arginine 277 have been studied. The role of arginine 277 in (S)-mandelate dehydrogenase in substrate binding and transition state stabilization was the study focus. Results indicate that R277 has an important role in transition state stabilization via its positive charge and forms a certain hydrogen bond with the substrate and the transition state. Results relative to the stabilization are consistent with a mechanism that involves a carbanion intermediate.

Results indicate that there is a 10-15 fold increase in the rate of 5,10-methylene-5,6,7,8-tetrahydrofolate enzyme due to arginines stabilizing the closed conformation of thymidylate synthase ternary complexes. Data further show that the arginine residues ideally complement phosphate moiety's charge and geometry.

Results demonstrate the structure of a 10 base loop DNA complexed with argininamide as determined by NMR. Data reveal complex binding kinetics indicating a slow interconversiton of DNA forms exhibiting different binding affinities.

Small G proteins and magnesium fluoride-dependent binding to their GTPase-activating proteins (GAPs) are discussed. Magnesium-dependent fluoride effects may be a general phenomenon with G proteins. Data indicate that some protein*nucleotide complexes reported to contain aluminum fluoride may have magnesium fluoride in them.

The role of arginine 719 found in human plasminogen in the formation of the staphylokinase:plasmin activator complex was investigated. Alanine-mutagenesis was applied to phage-displayed micro-plasminogen to determine the plasmin residues required for generating the staphylokinase: plasmin activator interface. Results showed that replacement of arginine 719 with Ala dramatically reduces the binding affinity and plasminogen activation potential of the staphylokinase:micro-plasminogen complex.

Experimental analysis of the role of Arg290 during macromolecular substrate factor X activation reveals that Arg290 activates the natural substrate X. Substitution of Arg290 with alanine results in the disruption of activation and a 4-5-fold reduction of Kcat with and without cofactor contents. However, the substitutions have no effect on the catalytic triad activity of the VIIa Arg290 - A bond, even in the presence of peptidyl P-nitroanilide substrates.

L-arginine and molecular oxygen are used to prepare nitric oxide (NO) and citrulline. This reaction relies on NADPH and is catalyzed by the rat-brain NO synthase (NOS) group of enzymes. N(G)-hydroxy-L-arginine (NOHArg), an isolable intermediate, is produced by subjecting L-arginine to hydroxylation. NO and citrulline are derived by adding a second atom of oxygen when NOHArg undergoes metabolism. Heme iron, FAD, FMN, and tetrahydrobiopterin are seen in NOS. Substrate perturbation difference spectrophotometry is used to study the reaction between the substrates and the heme prosthetic group.

The calcium- or calmodulin-dependent constitutive nitric oxide synthase (cNOS) from bovine brain was a catalyst for the L-arginine oxidation and the L-arginine-independent NADPH oxidation reactions, which were prevented by L-NG-nitroarginine (NA). Calmodulin, calcium and NADPH did not need NA binding. A second-order association rate constant and the dissociation rate constant were determined by the slow prevention process. NA binding was hindered by L-arginine. L-arginine was oxidated by titrating the NA binding sites of cNOS with NA, and the NA-inducible mouse macrophage NOS (iNOS) was repressed.

Research has been conducted on arginine and its structural analogues. The preparation of syn- and anti-trans-cyclopropyl arginine is described.

Research has been conducted on proline- and arginine-rich antibacterial peptide PR39. The authors have demonstrated that this peptide is a noncompetitive and reversible inhibitor of the proteasome function.