Crystal structure of the stimulatory complex of GTP cyclohydrolase I and its feedback regulatory protein GFRP

Maita, N.; Okada, Kengo; Hatakeyama, Kazuyuki; Hakoshima, Toshio

doi:10.1073/pnas.022646999

Cited by 50 publications

(93 citation statements)

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“…7). These Zn 2ϩ liganding side chains and coordination geometry are preserved in all available structures of zinc-containing GCYH-IA, including the human (2) and rat (31,32) enzymes. In contrast, in GCYH-IB, the metal binding site is formed by two GCYH-IB-specific insertions: the helix-loop insertion (␣3) between the first two ␤-strands of the T-fold (␤5 and ␤6) and the helical insertion ␣5 from the neighboring subunit.…”

Section: Vol 191 2009mentioning

confidence: 99%

Zinc-Independent Folate Biosynthesis: Genetic, Biochemical, and Structural Investigations Reveal New Metal Dependence for GTP Cyclohydrolase IB

et al. 2009

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GTP cyclohydrolase I (GCYH-I) is an essential Zn2؉ -dependent enzyme that catalyzes the first step of the de novo folate biosynthetic pathway in bacteria and plants, the 7-deazapurine biosynthetic pathway in Bacteria and Archaea, and the biopterin pathway in mammals. We recently reported the discovery of a new prokaryoticspecific GCYH-I (GCYH-IB) that displays no sequence identity to the canonical enzyme and is present in ϳ25% of bacteria, the majority of which lack the canonical GCYH-I (renamed GCYH-IA). Genomic and genetic analyses indicate that in those organisms possessing both enzymes, e.g., Bacillus subtilis, GCYH-IA and -IB are functionally redundant, but differentially expressed. Whereas GCYH-IA is constitutively expressed, GCYH-IB is expressed only under Zn 2؉ -limiting conditions. These observations are consistent with the hypothesis that GCYH-IB functions to allow folate biosynthesis during Zn 2؉ starvation. Here, we present biochemical and structural data showing that bacterial GCYH-IB, like GCYH-IA, belongs to the tunneling-fold (T-fold) superfamily. However, the GCYH-IA and -IB enzymes exhibit significant differences in global structure and activesite architecture. While GCYH-IA is a unimodular, homodecameric, Zn 2؉ -dependent enzyme, GCYH-IB is a bimodular, homotetrameric enzyme activated by a variety of divalent cations. The structure of GCYH-IB and the broad metal dependence exhibited by this enzyme further underscore the mechanistic plasticity that is emerging for the T-fold superfamily. Notably, while humans possess the canonical GCYH-IA enzyme, many clinically important human pathogens possess only the GCYH-IB enzyme, suggesting that this enzyme is a potential new molecular target for antibacterial development.The Zn 2ϩ

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Section: Vol 191 2009mentioning

confidence: 99%

Zinc-Independent Folate Biosynthesis: Genetic, Biochemical, and Structural Investigations Reveal New Metal Dependence for GTP Cyclohydrolase IB

et al. 2009

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“…When the concentration of Mg-free GTP was fixed at 10 lM, the concentrations of MgCl 2 in the reaction mixture were 35, 70, 105, 140, 175 and 210 lM at the total GTP concentrations of 15,20,25,30,35 and 40 lM, respectively ( Fig. 3A and B).…”

Section: Gch Recognizes Mg-free Gtpmentioning

confidence: 99%

“…The presence of Zn 2+ during the refolding procedure elicited a To fix the concentration of Mg-free GTP at 10 lM constant, we adjusted the concentrations of MgCl 2 in the reaction mixture to 35, 70, 105, 140, 175, and 210 lM at the total GTP concentrations of 15,20,25,30,35, and 40 lM, respectively. Under these conditions at a constant 10 lM Mg-free GTP (A; s), the concentrations of Mg-GTP complex (A; d) and Mg 2+ (B; n) were plotted.…”

Section: Requirement Of Zn 2+ For the Gch Enzymatic Activitymentioning

confidence: 99%

“…By crystallographic analysis using purified Escherichia coli enzyme [14], an N-terminally truncated form of the recombinant human enzyme [12], and a stimulatory complex of rat GCH and GFRP induced by phenylalanine [15], Zn 2+ was shown to be bound to the active centre of the homodecameric GCH enzyme. As for Ca 2+ , mutations of the recombinant rat enzyme in an EF-hand-like motif, which is absent in bacteria, inhibited both the binding of Ca 2+ to the enzyme and enzyme activity [13].…”

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confidence: 99%

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GTP cyclohydrolase I utilizes metal‐free GTP as its substrate

Suzuki

Kurita

Ichinose

2003

European Journal of Biochemistry

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GTP cyclohydrolase I (GCH) is the rate-limiting enzyme for the synthesis of tetrahydrobiopterin and its activity is important in the regulation of monoamine neurotransmitters such as dopamine, norepinephrine and serotonin. We have studied the action of divalent cations on the enzyme activity of purified recombinant human GCH expressed in Escherichia coli. First, we showed that the enzyme activity is dependent on the concentration of Mg-free GTP. Inhibition of the enzyme activity by Mg 2+ , as well as by Mn 2+ , Co 2+ or Zn 2+ , was due to the reduction of the availability of metal-free GTP substrate for the enzyme, when a divalent cation was present at a relatively high concentration with respect to GTP. We next examined the requirement of Zn 2+for enzyme activity by the use of a protein refolding assay, because the recombinant enzyme contained approximately one zinc atom per subunit of the decameric protein. Only when Zn 2+ was present was the activity of the denatured enzyme effectively recovered by incubation with a chaperone protein. These are the first data demonstrating that GCH recognizes Mg-free GTP and requires Zn 2+ for its catalytic activity. We suggest that the cellular concentration of divalent cations can modulate GCH activity, and thus tetrahydrobiopterin biosynthesis as well.Keywords: GTP cyclohydrolase I; magnesium; recombinant protein; tetrahydrobiopterin; zinc.Metal ions are essential for many physiological functions of the brain. They may also induce or aggravate numerous neurodegenerative processes. Thus, it is important to understand the roles of metal ions in normal and pathological brain functions.GTP cyclohydrolase I (GCH) is the rate-limiting enzyme for the biosynthesis of tetrahydrobiopterin (BH 4 ), and the cellular BH 4 content is regulated mainly by the activity of this enzyme. BH 4 is an essential cofactor for three aromatic amino-acid monooxygenases ) phenylalanine, tyrosine, and tryptophan hydroxylases -and for nitric oxide synthase [1]. BH 4 deficiency caused not only a decrease in the activity of these enzymes but also a decrease in the protein levels of tyrosine hydroxylase and nitric oxide synthase [2,3]. Therefore, the availability of BH 4 affects the amounts of neurotransmitters such as catecholamines, serotonin, melatonin and nitric oxide. The role of BH 4 in the activity of nitric oxide synthase also makes BH 4 an important factor for the immune system and endothelial cell function.Various hormones and cytokines are known to induce the expression of the GCH gene in neural, lymphocytic and endothelial cells, and in different cell lines, resulting in an increased BH 4 content [4][5][6][7][8]. At the post-transcriptional level, BH 4 was shown to inhibit, and phenylalanine to stimulate, GCH activity through interaction with GFRP, a GTP cyclohydrolase I feedback regulatory protein [9]. GCH, which is a homodecameric protein, shows positive cooperativity against the GTP substrate [10] and phenylalanine changes the substrate velocity curve from sigmoidal to hyperbolic [11].Recent...

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“…Az első lépéshez szükséges guanozin-trifoszfát-ciklohidroláz (GTPCH) enzimet egy regulálófehérje, a GTP cyclohydrolase feedback regulatory protein (GFRP) visszacsatolással szabályozza az aktuális fenilalanin-, illetve BH 4 -szinttől függően [6]. Az ábrán feltüntetett lépések közül a harmadik nem egyformán zajlik az agyban, illetve a májban, így fordulhat elő, hogy sepiapterin-reduktáz (SR)-deficientiánál az agyban elégtelen a szintetizálódott BH 4 mennyisége, míg a máj-ban ugyanez megfelelő lehet.…”

Section: Patomechanizmusunclassified

A tetrahidrobiopterin (BH₄)-deficientia diagnosztikája és kezelése

Bókay

2017

Orvosi Hetilap

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Azt követően, hogy Følling felfedezte, hogy az alacsony fenilalanin-tartalmú diétával a phenylketonuria súlyos idegrendszeri tünetei megelőzhetők, hamarosan kiderült, hogy a fenilalanin-hidroxiláz enzim működési zavarán kívül kofaktorának, a tetrahidrobiopterinnek a hiánya, illetve működési zavara is okozhat fenilalanin-anyagcsere-zavart és társuló súlyos neurológiai tüneteket. A tetrahidrobiopterin a fenilalanin-anyagcserében játszott szerepén kívül egyidejűleg különböző neurotranszmitterek, katecholaminok és a szerotonin szintéziséhez szükséges enzimeknek, a tirozinhidroxiláznak és a triptofán-hidroxiláznak is kofaktora. Így a tetrahidrobiopterin-defektusban szenvedő betegek esetében a hyperphenylalaninaemián kívül a dopamin-és szerotoninhiány következében számos egyéb idegrendszeri tünet is megfigyelhető. Az érintett betegek megfelelő kezelés nélkül többnyire mentális retardációval társuló súlyos neurológiai tüneteket mutatnak, az enyhe klinikai lefolyás viszonylag ritka. A korán felállított kórisme és az adekvát kezelés mielőbbi megkezdése minimalizálhatja a tüneteket és javítja a kórlefolyást, valamint a prog nózist. Orv Hetil. 2017; 158(48): 1897-1902. Kulcsszavak: phenylketonuria, tetrahidrobiopterin-deficientia Tetrahydrobiopterin (BH 4 ) deficiency -diagnosis and treatmentSince the initial breaking discovery of Følling that the severe neurological consequences of phenylketonuria could be prevented by use of low phenylalanine (Phe) diet, it has been shortly recognised that defective phenylalanine metabolism may also arise from the deficiency of tetrahydrobiopterin (BH 4 ) cofactor, required for phenylalanine-hydroxylase activity. Furthermore, as BH 4 is in Phe metabolism, it is also a cofactor for the activities of tyrosine hydroxylase and tryptophane hydroxylase, enzymes required for the synthesis of catecholamines and serotonin neurotransmitters. Besides hyperphenylalaninemia in patients with tetrahydrobiopterin deficiencies, dopamine and serotonin deficiencies, with different disorders of the central nervous system also develop. Mild form of tetrahydrobiopterin deficiency is rare, most of the patients have severe neurological abnormalities including progressive mental retardation if not treated properly. Early diagnosis and treatment are essential and can improve the clinical course and prognosis. Rövidítések 5-HT = (5-hydroxytryptamine) 5-hidroxi-triptamin -szerotonin; 5-OHT = (5-hydroxytryptophan) 5-hidroxi-triptofán; adGTPCH = autoszomális domináns guanozintrifoszfát-ciklohidroláz; arGTPCH = autoszomális recesszív guanozintrifoszfát-ciklohidroláz; BH 4 = (tetrahydrobiopterin) tetrahidrobiopterin; COMT = (catechol-O-methyltransferase) katechol-O-metil-transzferáz; DBS = (dried blood sample) szűrőpapíros beszárított vérminta; DHPR = (dihydropteridine reductase) dihidropteridin-reduktáz; DOPA = 3,4-dihidroxifenilalanin; DRD = (DOPA responsive dystonia) DOPA-reszponzív dystonia; GFRP = (GTP-cycrohydrolase feedback regulatory protein) GTP-cikrohidroláz feedback regulálófehérje; GTP = (guanosine triphosp...

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Crystal structure of the stimulatory complex of GTP cyclohydrolase I and its feedback regulatory protein GFRP

Cited by 50 publications

References 39 publications

Zinc-Independent Folate Biosynthesis: Genetic, Biochemical, and Structural Investigations Reveal New Metal Dependence for GTP Cyclohydrolase IB

Zinc-Independent Folate Biosynthesis: Genetic, Biochemical, and Structural Investigations Reveal New Metal Dependence for GTP Cyclohydrolase IB

GTP cyclohydrolase I utilizes metal‐free GTP as its substrate

A tetrahidrobiopterin (BH₄)-deficientia diagnosztikája és kezelése

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Crystal structure of the stimulatory complex of GTP cyclohydrolase I and its feedback regulatory protein GFRP

Cited by 50 publications

References 39 publications

Zinc-Independent Folate Biosynthesis: Genetic, Biochemical, and Structural Investigations Reveal New Metal Dependence for GTP Cyclohydrolase IB

Zinc-Independent Folate Biosynthesis: Genetic, Biochemical, and Structural Investigations Reveal New Metal Dependence for GTP Cyclohydrolase IB

GTP cyclohydrolase I utilizes metal‐free GTP as its substrate

A tetrahidrobiopterin (BH4)-deficientia diagnosztikája és kezelése

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A tetrahidrobiopterin (BH₄)-deficientia diagnosztikája és kezelése