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Literature summary extracted from

  • Claas, K.R.; Parrish, J.R.; Maggio-Hall, L.A.; Escalante-Semerena, J.C.
    Functional analysis of the nicotinate mononucleotide:5,6-dimethylbenzimidazole phosphoribosyltransferase (CobT) enzyme, involved in the late steps of coenzyme B12 biosynthesis in Salmonella enterica (2010), J. Bacteriol., 192, 145-154.
    View publication on PubMedView publication on EuropePMC

Cloned(Commentary)

EC Number Cloned (Comment) Organism
2.4.2.21 wild-type and mutants cloned into vector pSU18 or vector pT7-5. Plasmids carrying wild-type or mutant cobT alleles introduced into strain JE2607 (cobT cobB recA) or strain JE2423 (cobT recA). Plasmids encoding mutant cobT alleles under the control of the T7 promoter of vector pT7-5 transformed into strain JE2017 and overexpressed Salmonella enterica

Protein Variants

EC Number Protein Variants Comment Organism
2.4.2.21 C160A loss of catalytic efficiency by 79%. Renders the enzyme 5fold less efficient than wild-type. Displays no discernible growth defect in no-carbon essential (NCE) medium containing dicyanocobinamide and glycerol or ethanolamine relative to that of a strain that synthesizes wild-type Salmonella enterica
2.4.2.21 G171D loss of catalytic efficiency by more than 99%, has less affinity for 5,6-dimethylbenzimidazole. Retains activity to support growth, but only when 5,6-dimethylbenzimidazole is present in the medium. Does not support the growth of strain JE2423 on ethanolamine in medium that contains dicyanocobinamide but lacks 5,6-dimethylbenzimidazole Salmonella enterica
2.4.2.21 G171D/M325A requires cobalamin for growth regardless of the carbon source used Salmonella enterica
2.4.2.21 G257A loss of catalytic efficiency by 64% Salmonella enterica
2.4.2.21 G257D loss of catalytic efficiency by more than 99%, has less affinity for 5,6-dimethylbenzimidazole. Does not respond to 5,6-dimethylbenzimidazole and requires cobalamin to grow. Does not support the growth of strain JE2423 on ethanolamine in medium that contains dicyanocobinamide but lacks 5,6-dimethylbenzimidazole Salmonella enterica
2.4.2.21 G257D/P12G is cobalamin auxotroph on glycerol or ethanolamine. P12G does not alter the effect of the G257D mutation Salmonella enterica
2.4.2.21 G320D loss of catalytic efficiency by more than 99%, is unstable, retains activity to support growth, but only when 5,6-dimethylbenzimidazole is present in the medium. Does not support the growth of strain JE2423 on ethanolamine in medium that contains dicyanocobinamide but lacks 5,6-dimethylbenzimidazole Salmonella enterica
2.4.2.21 H289A counteracts the effect of the G320D substitution Salmonella enterica
2.4.2.21 M325A grows in the absence of exogenous 5,6-dimethylbenzimidazole, albeit at a rate slower than that of a strain making wild-type. Addition of 5,6-dimethylbenzimidazole to the medium allows the strain making M325A to grow as fast as a strain making wild-type Salmonella enterica
2.4.2.21 P12G does not require exogenous 5,6-dimethylbenzimidazole for growth on glycerol or ethanolamine Salmonella enterica

KM Value [mM]

EC Number KM Value [mM] KM Value Maximum [mM] Substrate Comment Organism Structure
2.4.2.21 0.3
-
 beta-nicotinate D-ribonucleotide mutant G257A, at 37°C Salmonella enterica
2.4.2.21 0.3
-
 beta-nicotinate D-ribonucleotide wild-type, at 37°C Salmonella enterica
2.4.2.21 0.9
-
 beta-nicotinate D-ribonucleotide mutant G171D, at 37°C Salmonella enterica
2.4.2.21 1
-
 beta-nicotinate D-ribonucleotide mutant G320D, at 37°C Salmonella enterica
2.4.2.21 1.2
-
 beta-nicotinate D-ribonucleotide mutant C160A, at 37°C Salmonella enterica
2.4.2.21 2.2
-
 beta-nicotinate D-ribonucleotide mutant G257D, at 37°C Salmonella enterica

Organism

EC Number Organism UniProt Comment Textmining
2.4.2.21 Salmonella enterica Q05603
-
-

Purification (Commentary)

EC Number Purification (Comment) Organism
2.4.2.21 by gel filtration Salmonella enterica

Specific Activity [micromol/min/mg]

EC Number Specific Activity Minimum [µmol/min/mg] Specific Activity Maximum [µmol/min/mg] Comment Organism
2.4.2.21 0.1
-
 mutant G257D, at 37°C Salmonella enterica
2.4.2.21 0.2
-
 mutant G320D, at 37°C Salmonella enterica
2.4.2.21 0.5
-
 mutant G171D, at 37°C Salmonella enterica
2.4.2.21 11
-
 mutant G257A, at 37°C Salmonella enterica
2.4.2.21 25
-
 mutant C160A, at 37°C Salmonella enterica
2.4.2.21 30
-
 wild-type, at 37°C Salmonella enterica

Storage Stability

EC Number Storage Stability Organism
2.4.2.21 -80°C, 50 mM Tris-HCl buffer, pH 7.5, 3 M glycerol Salmonella enterica

Substrates and Products (Substrate)

EC Number Substrates Comment Substrates Organism Products Comment (Products) Rev. Reac.
2.4.2.21 beta-nicotinate D-ribonucleotide + 5,6-dimethylbenzimidazole
-
 Salmonella enterica nicotinate + N1-(5-phospho-alpha-D-ribosyl)-5,6-dimethylbenzimidazole
-
 ?

Synonyms

EC Number Synonyms Comment Organism
2.4.2.21 5,6-dimethylbenzimidazole phosphoribosyltransferase
-
 Salmonella enterica
2.4.2.21 CobT
-
 Salmonella enterica

Turnover Number [1/s]

EC Number Turnover Number Minimum [1/s] Turnover Number Maximum [1/s] Substrate Comment Organism Structure
2.4.2.21 0.2
-
 beta-nicotinate D-ribonucleotide mutant G257D, at 37°C Salmonella enterica
2.4.2.21 0.2
-
 beta-nicotinate D-ribonucleotide mutant G320D, at 37°C Salmonella enterica
2.4.2.21 0.6
-
 beta-nicotinate D-ribonucleotide mutant G171D, at 37°C Salmonella enterica
2.4.2.21 14
-
 beta-nicotinate D-ribonucleotide mutant G257A, at 37°C Salmonella enterica
2.4.2.21 31
-
 beta-nicotinate D-ribonucleotide mutant C160A, at 37°C Salmonella enterica
2.4.2.21 38
-
 beta-nicotinate D-ribonucleotide wild-type, at 37°C Salmonella enterica

kcat/KM [mM/s]

EC Number kcat/KM Value [1/mMs-1] kcat/KM Value Maximum [1/mMs-1] Substrate Comment Organism Structure
2.4.2.21 0.1
-
 beta-nicotinate D-ribonucleotide mutant G257D, at 37°C Salmonella enterica
2.4.2.21 0.2
-
 beta-nicotinate D-ribonucleotide mutant G320D, at 37°C Salmonella enterica
2.4.2.21 0.7
-
 beta-nicotinate D-ribonucleotide mutant G171D, at 37°C Salmonella enterica
2.4.2.21 29
-
 beta-nicotinate D-ribonucleotide mutant C160A, at 37°C Salmonella enterica
2.4.2.21 50
-
 beta-nicotinate D-ribonucleotide mutant G257A, at 37°C Salmonella enterica
2.4.2.21 138
-
 beta-nicotinate D-ribonucleotide wild-type, at 37°C Salmonella enterica