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Literature summary extracted from

  • Grochowski, L.L.; Xu, H.; Leung, K.; White, R.H.
    Characterization of an Fe(2+)-dependent archaeal-specific GTP cyclohydrolase, MptA, from Methanocaldococcus jannaschii (2007), Biochemistry, 46, 6658-6667.
    View publication on PubMed

Cloned(Commentary)

EC Number Cloned (Comment) Organism
3.5.4.16 expressed in Escherichia coli strain BL21-Codon Plus (DE3)-PIL Methanocaldococcus jannaschii
3.5.4.39 expression in Escherichia coli Methanocaldococcus jannaschii

Protein Variants

EC Number Protein Variants Comment Organism
3.5.4.16 H101N shows wild type activity Methanocaldococcus jannaschii
3.5.4.16 H200N shows reduced enzymatic activity but no reduction in the amount of bound iron Methanocaldococcus jannaschii
3.5.4.16 H293N shows reduced enzymatic activity but no reduction in the amount of bound iron Methanocaldococcus jannaschii
3.5.4.16 H295N shows reduced enzymatic activity but no reduction in the amount of bound iron Methanocaldococcus jannaschii
3.5.4.39 C163S-alkylcysteine when incubated with N-ethylmaleimide, the enzyme loses 67% activity. Iodoacetamide reduces activity by 33% Methanocaldococcus jannaschii
3.5.4.39 E50D no effect on specific activity of the enzyme Methanocaldococcus jannaschii
3.5.4.39 H101N mutation does not affect the ability of the enzyme to form dihydro-D-neopterin 2',3'-cyclic phosphate nor does it have a reduced amount of iron Methanocaldococcus jannaschii
3.5.4.39 H200N/E50D decrease in the specific activity Methanocaldococcus jannaschii
3.5.4.39 H293N decrease in the specific activity Methanocaldococcus jannaschii
3.5.4.39 H295N decrease in the specific activity Methanocaldococcus jannaschii
3.5.4.39 H295N results in a majority of the protein being expressed in an insoluble form Methanocaldococcus jannaschii

Inhibitors

EC Number Inhibitors Comment Organism Structure
3.5.4.16 7-methyl-GTP 36% inhibition at 2 mM GMP Methanocaldococcus jannaschii
3.5.4.16 dGTP 28% inhibition at 2 mM GMP Methanocaldococcus jannaschii
3.5.4.16 fapy-GMP 1 mM results in a 5fold reduction in activity Methanocaldococcus jannaschii
3.5.4.16 GMP 43% inhibition at 2 mM GMP Methanocaldococcus jannaschii
3.5.4.16 additional information Mn2+ enzyme is not inactivated by exposure to oxygen Methanocaldococcus jannaschii
3.5.4.16 oxygen
-
 Methanocaldococcus jannaschii
3.5.4.39 7-methyl-GTP included along with 2 mM GTP in the incubation mixture. 36% inhibition Methanocaldococcus jannaschii
3.5.4.39 dGTP included along with 2 mM GTP in the incubation mixture. 28% inhibition Methanocaldococcus jannaschii
3.5.4.39 fapy-GMP coincubation of MptA with fapyGMP (about 1 mM) and GTP (2 mM) results in a 5-fold reduction in activity Methanocaldococcus jannaschii
3.5.4.39 GMP included along with 2 mM GTP in the incubation mixture. 43% inhibition Methanocaldococcus jannaschii

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
3.5.4.39 0.096
-
 GTP pH 7.2, 70°C Methanocaldococcus jannaschii

Metals/Ions

EC Number Metals/Ions Comment Organism Structure
3.5.4.16 Fe2+ dependent, contains 1 Fe2+ per protomer Methanocaldococcus jannaschii
3.5.4.16 Mn2+ at 2 mM Mn2+ is able to restore MptA activity to a higher level than Fe2+, Mn2+ enzyme is not inactivated by exposure to oxygen Methanocaldococcus jannaschii
3.5.4.39 Fe2+ required. Mutation of conserved histidine residues H200N, H293N, and H295N, expected to be involved in Fe2+ binding, results in reduced enzymatic activity but no reduction in the amount of bound iron Methanocaldococcus jannaschii
3.5.4.39 Zn2+ 0.5:1 molar ratio of zinc to enzyme monomer. The zinc content of the mutants H200N and H293N is similar to that of the wild type. Mutant H101N shows an increased amount of zinc (1:1 molar ratio of zinc to monomer) Methanocaldococcus jannaschii

Molecular Weight [Da]

EC Number Molecular Weight [Da] Molecular Weight Maximum [Da] Comment Organism
3.5.4.16 37000
-
 2 * 37000, SDS-PAGE Methanocaldococcus jannaschii
3.5.4.16 84000
-
 gel filtration Methanocaldococcus jannaschii
3.5.4.39 36300
-
 2 * 36300, SDS-PAGE Methanocaldococcus jannaschii
3.5.4.39 37000
-
 2 * 37000, SDS-PAGE Methanocaldococcus jannaschii
3.5.4.39 84000
-
 gel filration Methanocaldococcus jannaschii

Natural Substrates/ Products (Substrates)

EC Number Natural Substrates Organism Comment (Nat. Sub.) Natural Products Comment (Nat. Pro.) Rev. Reac.
3.5.4.16 additional information Methanocaldococcus jannaschii catalyzes the first step in the biosynthesis of methanopterin ?
-
 ?
3.5.4.16 additional information Methanocaldococcus jannaschii MJ0775 catalyzes the first step in the biosynthesis of methanopterin ?
-
 ?
3.5.4.39 GTP + H2O Methanocaldococcus jannaschii the enzyme is involved in methanopterin biosynthesis in methanogenic archaea 7,8-dihydroneopterin 2',3'-cyclic phosphate + formate + diphosphate
-
 ?

Organic Solvent Stability

EC Number Organic Solvent Comment Organism
3.5.4.16 dithiothreitol in the absence of dithiothreitol, MptA loses all activity within 4 days at -20°C, this activity can be restored by adding specific divalent metal ions to the oxygen-inactivated enzyme under anaerobic conditions in the presence of dithiothreitol Methanocaldococcus jannaschii

Organism

EC Number Organism UniProt Comment Textmining
3.5.4.16 Methanocaldococcus jannaschii
-
-
-
3.5.4.16 Methanocaldococcus jannaschii MJ0775
-
-
-
3.5.4.39 Methanocaldococcus jannaschii Q58185
-
-

Oxidation Stability

EC Number Oxidation Stability Organism
3.5.4.39 the enzyme readily loses activity upon exposure to air. MptA loses all activity within 4 days at -20°C. This activity can be restored by adding specific divalent metal ions to the oxygen-inactivated enzyme under anaerobic conditions in the presence of dithiothreitol. Only Fe2+ is capable of restoring activity at the physiologically relevant concentrations of 0.020 mM. Higher concentrations of Mn2+ (0.2 mM) are able to restore activity to 24% of that seen with the Fe2+. At very high concentrations (2 mM) Mn2+ is able to restore MptA activity to a higher level than Fe2+. The Mn2+ enzyme is not inactivated by exposure to oxygen. The addition of reducing agents to the assay mixture is able to partially restore activity in oxygen inactivated MptA Methanocaldococcus jannaschii

Purification (Commentary)

EC Number Purification (Comment) Organism
3.5.4.16 Mono Q HR column chromatography Methanocaldococcus jannaschii
3.5.4.39
-
 Methanocaldococcus jannaschii

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
3.5.4.16 beta,gamma-methyleneguanosine 5'-triphosphate + H2O
-
 Methanocaldococcus jannaschii dihydroneopterin 2',3'-cyclic phosphate + ?
-
 ?
3.5.4.16 beta,gamma-methyleneguanosine 5'-triphosphate + H2O
-
 Methanocaldococcus jannaschii MJ0775 dihydroneopterin 2',3'-cyclic phosphate + ?
-
 ?
3.5.4.16 GDP + H2O
-
 Methanocaldococcus jannaschii dihydroneopterin 2',3'-cyclic phosphate + ?
-
 ?
3.5.4.16 GDP + H2O
-
 Methanocaldococcus jannaschii MJ0775 dihydroneopterin 2',3'-cyclic phosphate + ?
-
 ?
3.5.4.16 GTP + H2O
-
 Methanocaldococcus jannaschii formate + 2-amino-4-hydroxy-6-(erythro-1,2,3-trihydroxypropyl)dihydropteridine triphosphate
-
 ?
3.5.4.16 GTP + H2O
-
 Methanocaldococcus jannaschii MJ0775 formate + 2-amino-4-hydroxy-6-(erythro-1,2,3-trihydroxypropyl)dihydropteridine triphosphate
-
 ?
3.5.4.16 GTP + H2O
-
 Methanocaldococcus jannaschii formate + 7,8-dihydro-D-neopterin 2',3'-cyclic phosphate + diphosphate
-
 ?
3.5.4.16 guanosine 5'-[gamma-thio]triphosphate + H2O
-
 Methanocaldococcus jannaschii dihydroneopterin 2',3'-cyclic phosphate + ?
-
 ?
3.5.4.16 additional information catalyzes the first step in the biosynthesis of methanopterin Methanocaldococcus jannaschii ?
-
 ?
3.5.4.16 additional information no activity towards dGTP, ATP, GMP, ITP, fapy-GTP, or 7-methyl-GTP Methanocaldococcus jannaschii ?
-
 ?
3.5.4.16 additional information catalyzes the first step in the biosynthesis of methanopterin Methanocaldococcus jannaschii MJ0775 ?
-
 ?
3.5.4.16 additional information no activity towards dGTP, ATP, GMP, ITP, fapy-GTP, or 7-methyl-GTP Methanocaldococcus jannaschii MJ0775 ?
-
 ?
3.5.4.39 beta,gamma-methylene-GTP + H2O hydrolyzed at 10% of the specific activity compared to GTP Methanocaldococcus jannaschii ?
-
 ?
3.5.4.39 GDP + H2O hydrolyzed at about 45% of the specific activity compared to GTP Methanocaldococcus jannaschii ?
-
 ?
3.5.4.39 GTP + H2O
-
 Methanocaldococcus jannaschii 7,8-dihydroneopterin 2',3'-cyclic phosphate + formate + diphosphate
-
 ?
3.5.4.39 GTP + H2O the enzyme is involved in methanopterin biosynthesis in methanogenic archaea Methanocaldococcus jannaschii 7,8-dihydroneopterin 2',3'-cyclic phosphate + formate + diphosphate
-
 ?
3.5.4.39 GTP-gamma-S + H2O hydrolyzed at 130% of the specific activity compared to GTP Methanocaldococcus jannaschii ?
-
 ?
3.5.4.39 additional information no activity with: dGTP, GMP, 7-methyl-GTP, ATP, fapy-GMP or ITP Methanocaldococcus jannaschii ?
-
 ?

Subunits

EC Number Subunits Comment Organism
3.5.4.16 homodimer 2 * 37000, SDS-PAGE Methanocaldococcus jannaschii
3.5.4.39 dimer 2 * 37000, SDS-PAGE Methanocaldococcus jannaschii
3.5.4.39 dimer 2 * 36300, SDS-PAGE Methanocaldococcus jannaschii

Synonyms

EC Number Synonyms Comment Organism
3.5.4.16 GTPCHI
-
 Methanocaldococcus jannaschii
3.5.4.16 MptA
-
 Methanocaldococcus jannaschii
3.5.4.39 GTP cyclohydrolase MptA
-
 Methanocaldococcus jannaschii
3.5.4.39 MptA
-
 Methanocaldococcus jannaschii

Temperature Optimum [°C]

EC Number Temperature Optimum [°C] Temperature Optimum Maximum [°C] Comment Organism
3.5.4.39 70
-
 assay at Methanocaldococcus jannaschii

Temperature Stability [°C]

EC Number Temperature Stability Minimum [°C] Temperature Stability Maximum [°C] Comment Organism
3.5.4.16 70 100 relative to a sample of the enzyme heated at 70°C for 10 min, MptA lost 27% activity when it is incubated or 10 min at 80°C, 60% activity at 90°C, and 89% activity at 100°C Methanocaldococcus jannaschii
3.5.4.39 80
-
 10 min, 27% loss of activity Methanocaldococcus jannaschii
3.5.4.39 90
-
 10 min, 60% loss of activity Methanocaldococcus jannaschii
3.5.4.39 100
-
 10 min, 89% loss of activity Methanocaldococcus jannaschii

pH Optimum

EC Number pH Optimum Minimum pH Optimum Maximum Comment Organism
3.5.4.16 6.5
-
-
 Methanocaldococcus jannaschii
3.5.4.39 6.5
-
-
 Methanocaldococcus jannaschii
3.5.4.39 7.2
-
 assay at Methanocaldococcus jannaschii

pH Range

EC Number pH Minimum pH Maximum Comment Organism
3.5.4.39 6 7.5 pH 6.0: 55% of maximal activity, pH 7.5: about 40% of maximal activity Methanocaldococcus jannaschii