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At least 19 recordsLinked to original sources
PubMed2001

Estrogen modulates the expression of L-arginine:glycine amidinotransferase in chick liver.

Identification of estrogen-responsive genes is important to understand the molecular mechanisms of estrogen action. Suppression subtractive hybridization was employed to screen estrogen-responsive genes in chick liver. A single injection of estrogen into 6-week-old chick induced up-regulation of several known genes encoded for yolk proteins, such as Vitellogenin I and II and very low density lipoprotein II (apo-VLDL II). One novel sequence displayed a dramatic change (3-fold increase) in response to estrogen treatment. This cDNA fragment was extended and the resultant sequence was analyzed. Translated amino acid sequence was 90, 88, 83 and 87% identical to the L-arginine:glycine amidinotransferase of pig, rat, frog and human, respectively. The sequence has a conservative catalytic site of L-arginine: glycine amidinotransferase. The expression pattern of this gene in organs is consistent with previous reports of L-arginine:glycine amidinotransferase in chick. Thus, this clone represented the chicken L-arginine:glycine amidinotransferase. It appeared that estrogen-induced alteration of arginine:glycine amidinotransferase was not dependent on protein synthesis, because concurrent administration of cycloheximide did not affect the estrogen-mediated expression pattern. This is the first study demonstrating that L-arginine:glycine amidinotransferase is a target of the estrogen receptor.

Amidinotransferases↗
PubMed2001

Isolation and characterization of the gene coding for the amidinotransferase involved in the biosynthesis of phaseolotoxin in Pseudomonas syringae pv. phaseolicola.

Pseudomonas syringae pv. phaseolicola is the causal agent of the "halo blight" disease of beans. A key component in the development of the disease is a nonhost-specific toxin, Ndelta-(N'-sulphodiaminophosphinyl)-ornithyl-alanyl-homoarginine, known as phaseolotoxin. The homoarginine residue in this molecule has been suggested to be the product of L-arginine:lysine amidinotransferase activity, previously detected in extracts of P. syringae pv. phaseolicola grown under conditions of phaseolotoxin production. We report the isolation and characterization of an amidinotransferase gene (amtA) from P. syringae pv. phaseolicola coding for a polypeptide of 362 residues (41.36 kDa) and showing approximately 40% sequence similarity to L-arginine:inosamine-phosphate amidinotransferase from three species of Streptomyces spp. and 50.4% with an L-arginine:glycine amidinotransferase from human mitochondria. The cysteine, histidine, and aspartic acid residues involved in substrate binding are conserved. Furthermore, expression of the amtA and argK genes and phaseolotoxin production occurs at 18 degrees C but not at 28 degrees C. An amidinotransferase insertion mutant was obtained that lost the capacity to synthesize homoarginine and phaseolotoxin. These results show that the amtA gene isolated is responsible for the amidinotransferase activity detected previously and that phaseolotoxin production depends upon the activity of this gene.

Amidinotransferases↗
PubMed1994

The amino acid sequences of human and pig L-arginine:glycine amidinotransferase.

We have isolated and sequenced the L-arginine:glycine amidinotransferase of pig kidney mitochondria. Due to endogenous proteolysis, the purified molecules showed some heterogeneity at the N terminus. The longest form recovered had 386 amino acids. Part of the pig amidinotransferase sequence information was used to isolate cDNA clones coding for the human enzyme. The deduced amino acid of the human amidinotransferase was 37 amino acids longer due to the presence of a single sequence. The mature proteins were 94% identical to each other and 36% identical to the sequences of bacterial L-arginine:inosamine phosphate amidinotransferases.

Amidinotransferases↗
PubMed1976

Creatine biosynthesis during embryonic development. False feedback suppression of liver amidinotransferase by N-acetimidoylsarcosine and 1-carboxymethyl-2-iminoimidazolidine (cyclocreatine).

The level of arginine:glycine amidinotransferase in liver of the developing chick embryo is partially suppressed following injection of arginine into the yolk, and the level can be completely suppressed following injection of guanidinoacetate or creatine (Walker, J.B. (1963), Proc. Soc. Exp. Biol. Med. 112, 245; Walker, J.B., and Wang, S.-H. (1964), Biochim, Biophys. Acta 81, 435). In this investigation structural requirements for the physiological suppressor were examined by testing certain analogues of creatine and its biosynthetic precursors for their ability to suppress liver amidinotransferase levels in developing chick embryos and growing chicks. The creatine analogues, N-acetimidoylsarcosine and 1-carboxymethyl-2-iminoimidazolidine (cyclocreatine), were found to suppress liver amidinotransferase levels of both developing embryos and growing chicks. Compounds ineffective as suppressors included: the arginine analogue, N5-acetimidoylornithine; the guanidinoacetate analogue, N-acetimidoylglycine; and the creatine analogue, 1-carboxymethyl-2-iminohexahydropyrimidine. Our findings suggest that (i) arginine and guanidinoacetate must be converted to creatine before serving as a suppressor, and (ii) creatine, not phosphocreatine, is most closely related to the physiological suppressor of amidinotransferase.

Amidinotransferases↗
PubMed1998

Crystal structure of L-arginine:inosamine-phosphate amidinotransferase StrB1 from Streptomyces griseus: an enzyme involved in streptomycin biosynthesis.

Inosamine-phosphate amidinotransferases catalyze two nonconsecutive transamidination reactions in the biosynthesis of the streptomycin family of antibiotics. L-Arginine:inosamine-phosphate amidinotransferase StrB1 from Streptomyces griseus (StrB1) was cloned as an N-terminal hexa-histidine fusion protein, purified by affinity chromatography, and crystallized, and its crystal structure was solved by Patterson search methods at 3.1 A resolution. The structure is composed of five betabeta alphabeta-modules which are arranged circularly into a pseudo-5-fold symmetric particle. The three-dimensional structure is closely related to the structure of human L-arginine:glycine amidinotransferase (AT), but five loops (the 40-, 170-, 220-, 250-, and 270-loop) are organized very differently. The major changes are found in loops around the active site which open the narrow active site channel of AT to form an open and solvent-exposed cavity. In particular, module II of StrB1 is AT-like but lacks a 10-residue alpha-helix in the 170-loop. The concomitant reorganization of neighboring surface loops that surround the active site, i.e., the 40-loop and the 270-loop, results in an arrangement of loops which allows an unrestricted access of substrates to the cavity. However, the residues which are involved in substrate binding and catalysis are conserved in AT and StrB1 and are at equivalent topological positions, suggesting a similar reaction mechanism among amidinotransferases. The binding site for L-arginine had been deduced from its complex with AT. Molecular modeling revealed a possible binding mode for the second substrate scyllo-inosamine 4-phosphate.

Amidinotransferases↗
PubMed1980

Inhibition of arginine-glycine amidinotransferase by ornithine. A possible mechanism for the muscular and chorioretinal atrophies in gyrate atrophy of the choroid and retina with hyperornithinemia.

The inhibitory effect of ornithine on L-arginine:glycine amidinotransferase (EC 2.1.4.1) was studied in crude rat kidney homogenates. The enzyme activity was linear with time up to 45 min and with protein up to 200 microgram. The apparent Km and V of amidinotransferase were 9.21 mM and 1.53 mu mol/g protein per min, respectively. The enzyme was competitively inhibited by ornithine, with a Ki of 0.253 mM. Kidney arginase was inhibited only slightly and non-competitively. The inhibition of amidinotransferase by ornithine may thus be important in creatine biosynthesis. In gyrate atrophy of the choroid and retina with hyperornithinemia, a human autosomal recessive disease caused by decreased ornithine aminotransferase activity, plasma ornithine concentrations are elevated 10-20-fold (0.65-1.35 mM during fasting). In consequence endogenous creatine production probably is severely decreased because of inhibition of the rate-limiting transamidination step by ornithine. The deficiency of creatine and further of readily available energy in the form of phosphocreatine is suggested to be involved in the pathogenesis of the choroidal, retinal and type II muscle fiver atrophies in gyrate atrophy.

Amidinotransferases↗
PubMed2002

Polyamine synthesis in plants. Purification and properties of amidinotransferase from soybean (Glycine max) axes.

Three-day-old soybean (Glycine max) seedlings were exposed to 0.4 M sorbitol solution for 4 h to induce amidinotransferase activity, with the corresponding enzyme being purified to homogeneity by chromatographic separation on DEAE-Sephacel, Sephacryl S-300 and L-arginine Sepharose 4B. The purified enzyme used L-arginine and L-glycine as the major donor/acceptor of the amidino group, respectively, with formation of guanidinoacetic acid and ornithine products being confirmed by ESI-MS. The enzyme is a tetrameric protein having a molecular mass of 240,000 Da, whose thiol group is needed for enzymatic activity. The K(M)s for arginine and glycine were 3.8 and 0.89 mM, respectively, with optimal temperature and pH being 37 degrees C and 9.5, respectively. The soybean amidinotransferase could be indirectly involved in nitrogen metabolism, as suggested by the observation that arginine:glycine amidinotransferase in soybean axes is indirectly involved in putrescine biosynthesis and displays feedback control at high levels of an endogenous regulator, putrescine.

Amidinotransferases↗
PubMed1998

The comparative amino acid sequences, substrate specificities and gene or cDNA nucleotide sequences of some prokaryote and eukaryote amidinotransferases: implications for evolution.

The amino acid sequences of the amidinotransferases and the nucleotide sequences of their genes or cDNA from four Streptomyces species (seven genes) and from the kidneys of rat, pig, human and human pancreas were compared. The overall amino acid and nucleotide sequences of the prokaryotes and eukaryotes were very similar and further, three regions were identified that were highly identical. Evidence is presented that there is virtually zero chance that the overall and high identity regions of the amino acid sequence similarities and the overall nucleotide sequence similarities between Streptomyces and mammals represent random match. Both rat and lamprey amidinotransferases were able to use inosamine phosphate, the amidine group acceptor of Streptomyces. We have concluded that the structure and function of the amidinotransferases and their genes has been highly conserved through evolution from prokaryotes to eukaryotes. The evolution has occurred with: (1) a high degree of retention of nucleotide and amino acid sequences; (2) a high degree of retention of the primitive Streptomyces guanine + cytosine (G + C) third codon position composition in certain high identity regions of the eukaryote cDNA; (3) a decrease in the specificities for the amidine group acceptors; and (4) most of the mutations silent in the regions suggested to code for active sites in the enzymes.

Amidinotransferases↗
PubMed2004

Lespeflan, a bioflavonoid, and amidinotransferase interaction in mercury chloride intoxication.

Amidinotransferase (transamidinase, L-arginine: glycine amidinotransferase, EC 2.1.4.1) is an enzyme that catalyses the first step in creatine synthesis primarily in the kidney and pancreas. The kidney is also the primary target organ for the toxic effect of mercury. Therefore, we studied the effect of acute uremic syndrome on enzyme activity induced by mercury chloride. Because of the potential beneficial effect of bioflavonoids, we have investigated the effects of the bioflavonoid lespeflan on acute uremic syndrome and amidinotransferase activity. Male Spraque Dawley rats weighing about 200 g were used in this study. Acute renal failure was induced by intraperitoneally (i.p.) administration of mercury chloride in a dose of 3 mg/kg. One group of animals was given lespeflan (1.0 mL/kg) 1 hr before mercury chloride administration. Urea and creatinine levels in blood plasma were significantly elevated 48 hr after the induction of acute uremic syndrome (p< 0.001). Kidney transamidinase activity was decreased compared to the control group (p<0.001). Pretreatment by lespeflan potentiates the inhibitory effect of mercury chloride on enzyme activity. We discussed mechanisms of transamidinase inhibition and point thiol group of cysteine forming thiol-conjugates on enzyme inhibition both by mercury and lespeflan.

Acute Kidney Injury↗
PubMed2001

Expression of Xenopus L-arginine:glycine amidinotransferase (XAT) during early embryonic development.

We have isolated a full-length cDNA encoding Xenopus L-arginine:glycine amidinotransferase (XAT), which shares a highly conserved sequence with human, chick and rat amidinotransferase. Although there are some studies about its structure and function in energy metabolism of adult tissues in some other species, little is known about its roles during early embryonic development. Characterization of embryonic expression indicates that XAT is differentially expressed around the yolk plug including the dorsal blastopore area at early gastrula stages and is extensively expressed in the midline of the neural plate of early neurula stages. Sections reveal that its transcripts are located in the notochord. In the tailbud stage signals are found both in the notochord and trunk area, whereas only faint signals can be found in the cephalic part.

Amidinotransferases↗
PubMed2006

Arginine:glycine amidinotransferase (AGAT) deficiency in a newborn: early treatment can prevent phenotypic expression of the disease.

Arginine:glycine amidinotransferase deficiency is a treatable inborn error of creatine synthesis, characterized by mental retardation, language impairment, and behavioral disorders. We describe a patient in whom arginine:glycine amidinotransferase was diagnosed at birth and treated at 4 months with creatine supplementation. In contrast with his 2 older sisters, he had normal psychomotor development at 18 months.

Amidinotransferases↗
PubMed1999

The ligand-induced structural changes of human L-Arginine:Glycine amidinotransferase. A mutational and crystallographic study.

Human L-arginine:glycine amidinotransferase (AT) shows large structural changes of the 300-flap and of helix H9 upon binding of L-arginine and L-ornithine, described as a closed and an open conformation (Humm, A., Fritsche, E., Steinbacher, S., and Huber, R. (1997) EMBO J. 16, 3373-3385). To elucidate the structural basis of these induced-fit movements, the x-ray structures of AT in complex with the amidino acceptor glycine and its analogs gamma-aminobutyric acid and delta-aminovaleric acid, as well as in complex with the amidino donor analogs L-alanine, L-alpha-aminobutyric acid, and L-norvaline, have been solved at 2.6-, 2.5-, 2.37-, 2.3-, 2.5-, and 2.4-A resolutions, respectively. The latter three compounds were found to stabilize the open conformer. The glycine analogs bind in a distinct manner and do not induce the transition to the open state. The complex with glycine revealed a third binding mode, reflecting the rather broad substrate specificity of AT. These findings identified a role for the alpha-amino group of the ligand in stabilizing the open conformer. The kinetic, structural, and thermodynamic properties of the mutants ATDeltaM302 and ATDelta11 (lacks 11 residues of H9) confirmed the key role of Asn300 and suggest that in mammalian amidinotransferases, the role of helix H9 is in accelerating amidino transfer by an induced-fit mechanism. Helix H9 does not add to the stability of the protein.

Amidinotransferases↗
PubMed1997

Substrate binding and catalysis by L-arginine:glycine amidinotransferase--a mutagenesis and crystallographic study.

L-Arginine:glycine amidinotransferase catalyzes the committed step in the biosynthesis of creatine. Eight active-site mutants, D170N, D254N, H303V, D305A, R322E, S355A, C407S, and C410A of recombinant human L-arginine:glycine amidinotransferase were prepared by site-directed mutagenesis and enzymatically characterized. The crystal structures of the three mutants D170N, D254N, and C407S have been determined at 0.28-nm, 0.29-nm and 0.236-nm resolution, respectively. The mutation of active-site residues which are involved in substrate-binding yielded inactive mutants. Substitution of Asp254, which is not directly involved in substrate binding but is thought to transfer protons in concert with the His303 imidazole group, results in a strongly (2000-fold) reduced activity. However, the substitution of Cys410, a residue near the active site but not involved in catalysis or substrate binding, by Ala does not change the kinetic properties with respect to the wild-type enzyme. The loss of enzymatic activity of the D170N, D254N, C407S and likely all other mutants is solely due to the inserted point mutations, affecting substrate binding or transition-state stabilization, and not due to major conformational rearrangements of the protein. These results show that a His-Asp pair on one side of the substrate and a Cys on the other side are key residues for activity and are part of a disjoint triad. The imidazole ring of the His is proposed to act as a general acid/general base during catalysis whereas the Cys acts as a nucleophile analogous to Cys25 of papain-like cysteine proteinases.

Amidinotransferases↗
PubMed2002

A novel gene encoding amidinotransferase in the cylindrospermopsin producing cyanobacterium Aphanizomenon ovalisporum.

The hepatotoxin cylindrospermopsin is produced by several cyanobacteria species, which may flourish in tropical and sub-tropical lakes. Biosynthesis of cylindrospermopsin is poorly understood but its chemical nature, and feeding experiments with stable isotopes, suggested that guanidinoacetic acid is the starter unit and indicated involvement of a polyketide synthase. We have identified a gene encoding an amidinotransferase from the cylindrospermopsin producing cyanobacterium Aphanizomenon ovalisporum. This is the first report on an amidinotransferase gene in cyanobacteria. It is likely to be involved in the formation of guanidinoacetic acid. The aoaA is located in a genomic region bearing genes encoding a polyketide synthase and a peptide synthetase, further supporting its putative role in cylindrospermopsin biosynthesis.

Alkaloids↗
PubMed1994

Cloning and sequencing of rat kidney L-arginine:glycine amidinotransferase. Studies on the mechanism of regulation by growth hormone and creatine.

L-Arginine-glycine amidinotransferase (transamidinase) is the first and rate-limiting step in creatine biosynthesis. Rats fed a creatine-supplemented diet or hypophysectomized rats have only 20% of the kidney transamidinase activity as intact rats fed a creatine-free diet. A cDNA clone corresponding to transamidinase was isolated by immunoscreening of a lambda gt11 expression library prepared from rat kidney mRNA. The transamidinase cDNA had an open reading frame containing the known sequence of the amino-terminal peptide of transamidinase. Based on the cDNA sequence, transamidinase is synthesized as a precursor with an amino-terminal extension of 50 amino acids, consistent with its mitochondrial localization. Comparison of the transamidinase sequence with the protein data base identified only a single, related protein. Remarkably, this protein, which has a 37% amino acid identity with transamidinase, is also an amidinotransferase, catalyzing streptomycin biosynthesis in Streptomyces griseus. Transamidinase cDNA was used to investigate the regulation of mRNA levels by creatine and growth hormone. Hypophysectomized rats were fed a creatine-free or a creatine-supplemented diet and maintained with and without injections of growth hormone. An excellent correlation was found between changes in transamidinase activity and mRNA levels in response to creatine and growth hormone. Thus, the regulation of transamidinase by creatine and growth hormone is at a pretranslational level. In addition, the two effectors do not act independently but interact at a pretranslational level to control transamidinase gene expression.

Amidinotransferases↗
PubMed1986

The purification and characterization of human kidney L-arginine:glycine amidinotransferase.

Human kidney L-arginine:glycine amidinotransferase (transamidinase) has been purified to a homogeneous state as defined by native and sodium dodecyl sulfate gel electrophoresis and by ultracentrifugation (sedimentation equilibrium) experiments. The four steps in the isolation procedure were chromatography with DEAE-cellulose, gel filtration with Sephadex G-150, chromatography with phenyl Sepharose, and high-pressure liquid chromatography with hydroxylapatite. The final product represented a 90-fold purification of the enzyme. Human kidney transamidinase is a dimer with a molecular mass of 89,000 Da and subunit masses of 44,000 Da. The Km for arginine and glycine were both 2.5 mM and the Vmax was 0.5 mumol ornithine/min/mg protein. The ultraviolet absorption spectrum, specific activity, and isoelectric points were determined for human kidney transamidinase. Multiple forms of the enzyme were obtained by isoelectric focusing. Human kidney transamidinase cross-reacted with polyclonal antibodies raised to rat kidney transamidinase. All of the properties of human kidney transamidinase that we have examined were similar to those of rat kidney transamidinase. A close evolutionary relationship between the rat and human kidney transamidinase is suggested.

Amidinotransferases↗
PubMed1994

Synthesis of neuroactive guanidino compounds by rat kidney L-arginine: glycine amidinotransferase.

Several neuroactive guanidino compounds have been reported to be synthesized in mammals by transamidination reactions. The enzyme(s) responsible for their synthesis and their location in the body has not been well established. The purpose of this investigation was to determine if purified homogeneous rat kidney alpha- and beta-L-arginine : glycine amidinotransferase (transamidinase) would catalyze the synthesis of certain neuroactive guanidino compounds, and if so, to determine if any catalytic specificity existed between the two forms of the enzymes. L-Arginine (Arg) was used as the amidino group donor and the following compounds were investigated for their ability to accept the amidino group: ethanolamine; 4-aminobutyric acid; lysine; 5-aminovaleric acid; 3-aminopropionic acid; taurine; L-glutamic acid (Glu); L-aspartic acid (Asp); and histidine (His). All of the above listed compounds served as amidino group acceptors for the enzyme except Glu, Asp and His. No differences were found between the alpha- and beta-transamidinase in any of the experiments reported, and the synthesis of 2-guanidinoethanol by the enzyme was by a sequential mechanism with a Km for Arg and ethanolamine of 14mM and 163mM, respectively. The possibility that the site of synthesis of the neuroactive guanidino compounds in the kidney and perhaps pancreas is discussed.

Amidinotransferases↗
PubMed1997

Recombinant expression and isolation of human L-arginine:glycine amidinotransferase and identification of its active-site cysteine residue.

Creatine and its phosphorylated form play a central role in the energy metabolism of muscle and nerve tissues. l-Arginine:glycine amidinotransferase (AT) catalyses the committed step in the formation of creatine. The mitochondrial and cytosolic forms of the enzyme are believed to derive from the same gene by alternative splicing. We have expressed recombinant human AT in Escherichia coli with two different N-termini, resembling the longest two forms of the enzyme that we had isolated recently from porcine kidney mitochondria as a mixture. The enzymes were expressed with N-terminal histidine tags followed by factor Xa-cleavage sites. We established a new method for the removal of N-terminal fusion peptides by means of an immobilized snake venom prothrombin activator. We identified cysteine-407 as the active-site residue of AT by radioactive labelling and isolation of labelled peptides, and by site-directed mutagenesis of the protein.

Amidinotransferases↗