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Gene Review

proB  -  gamma-glutamate kinase

Escherichia coli str. K-12 substr. MG1655

Synonyms: ECK0243, JW0232, pro
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Disease relevance of proB


High impact information on proB

  • The Vigna P5CS enzyme activity is feedback regulated by proline but is less sensitive to end-product inhibition than is the E. coli gamma-glutamyl kinase [4].
  • Nucleotide sequence analysis of the proBA locus allowed gene assignments consistent with the NH2 and COOH-terminal analyses and amino acid compositions of homogeneous preparations of the proB and proA proteins [5].
  • 2. Differential utilization of proline and 1-pyrroline-5-carboxylate by the proB cells for the synthesis of protein, and failure of the method to distinguish between these two possible products of the proline-biosynthetic enzymes, might also give rise to error [6].
  • Comparison of the amino acid sequence of T. thermophilus gamma-glutamyl kinase with those of E. coli and S. marcescens mutants revealed that the DHP resistance mutations occurred in the amino acids conserved among the three organisms [7].
  • A proB mutant has a pleiotropic phenotype, being both proline auxotrophic and affected in cell morphology [8].

Chemical compound and disease context of proB


Biological context of proB

  • Gamma-delta insertion mutagenesis of this subcloned fragment indicated that proB and proA genes of V. parahaemolyticus might be transcribed from different promoters [12].
  • The proB and proA genes, closely linked in most bacteria, are in C. glutamicum separated by a 304-amino-acid open reading frame (unk) whose predicted sequence resembles that of the 2-hydroxy acid dehydrogenases [8].
  • The mutation, designated as proB74, is an allele of the Escherichia coli proB gene which results in a loss of allosteric regulation of the protein product, gamma-glutamyl kinase [11].
  • Plots of gamma-glutamyl kinase activity as a function of glutamate concentration were sigmoidal, with a half-saturation value for glutamate of 33 mM, whereas plots of enzyme activity as a function of ATP concentration displayed typical Michaelis-Menten kinetics with a Km for ATP of 4 X 10(-4) M [10].
  • Therefore, even though both the DHPR and the proB74 mutations caused a loss of allosteric inhibition of gamma-glutamyl kinase, they are due to different amino acid substitutions [11].

Associations of proB with chemical compounds

  • However, the capacity of glutamate-gamma-semialdehyde dehydrogenase from the osmotolerant mutant to interact with the kinase was altered in thermal stability, suggesting that mutations in both proB and proA may be required for osmotolerance [13].
  • While a 3.9 kb fragment which complemented proA also complemented proB, a 15 kb fragment complementing leuB could not complement other leu mutations [14].
  • When speF (which encodes ornithine decarboxylase) and proB (which encodes gamma-glutamyl kinase) were inactivated to prevent the conversion of L: -ornithine to putrescine and to block the biosynthesis of a side branch of L: -ornithine, respectively, L: -ornithine production was further enhanced approxi [15].

Other interactions of proB


Analytical, diagnostic and therapeutic context of proB

  • For eliminating the feedback inhibition, we first constructed a DHP-resistant mutant, TH401, by site-directed mutagenesis at the proB gene as reported for the proline-producing mutant of S. marcescens [7].


  1. Cloning and expression in Escherichia coli K-12 of the structural gene for outer membrane PhoE protein from Enterobacter cloacae. Verhoef, C., van Koppen, C., Overduin, P., Lugtenberg, B., Korteland, J., Tommassen, J. Gene (1984) [Pubmed]
  2. Directed evolution of an artificial bifunctional enzyme, gamma-glutamyl kinase/gamma-glutamyl phosphate reductase, for improved osmotic tolerance of Escherichia coli transformants. Chen, M., Cao, J., Zheng, C., Liu, Q. FEMS Microbiol. Lett. (2006) [Pubmed]
  3. Enhanced and feedback-resistant gamma-glutamyl kinase activity of an Escherichia coli transformant carrying a mutated proB gene of Streptococcus thermophilus. Massarelli, I., Forlani, G., Ricca, E., De Felice, M. FEMS Microbiol. Lett. (2000) [Pubmed]
  4. A bifunctional enzyme (delta 1-pyrroline-5-carboxylate synthetase) catalyzes the first two steps in proline biosynthesis in plants. Hu, C.A., Delauney, A.J., Verma, D.P. Proc. Natl. Acad. Sci. U.S.A. (1992) [Pubmed]
  5. Analysis of the Escherichia coli proBA locus by DNA and protein sequencing. Deutch, A.H., Rushlow, K.E., Smith, C.J. Nucleic Acids Res. (1984) [Pubmed]
  6. Proline biosynthesis by cell-free extracts of Escherichia coli and potential errors arising from the use of a bioradiological assay procedure. Hayzer, D.J., Moses, V. Biochem. J. (1978) [Pubmed]
  7. Construction of a proline-producing mutant of the extremely thermophilic eubacterium Thermus thermophilus HB27. Kosuge, T., Hoshino, T. Appl. Environ. Microbiol. (1998) [Pubmed]
  8. Mutations in the Corynebacterium glutamicum proline biosynthetic pathway: a natural bypass of th proA step. Ankri, S., Serebrijski, I., Reyes, O., Leblon, G. J. Bacteriol. (1996) [Pubmed]
  9. Cloning and characterization of the gamma-glutamyl phosphate reductase gene of Campylobacter jejuni. Louie, H., Chan, V.L. Mol. Gen. Genet. (1993) [Pubmed]
  10. Purification and characteristics of a gamma-glutamyl kinase involved in Escherichia coli proline biosynthesis. Smith, C.J., Deutch, A.H., Rushlow, K.E. J. Bacteriol. (1984) [Pubmed]
  11. Nucleotide sequence of a mutation in the proB gene of Escherichia coli that confers proline overproduction and enhanced tolerance to osmotic stress. Csonka, L.N., Gelvin, S.B., Goodner, B.W., Orser, C.S., Siemieniak, D., Slightom, J.L. Gene (1988) [Pubmed]
  12. Genetic and physical characterization of proBA genes of the marine bacterium Vibrio parahaemolyticus. Datta, A.R., Ostroff, R., MacQuillan, A.M. Appl. Environ. Microbiol. (1987) [Pubmed]
  13. Characterization of a gamma-glutamyl kinase from Escherichia coli that confers proline overproduction and osmotic tolerance. Smith, L.T. J. Bacteriol. (1985) [Pubmed]
  14. Cloning of genes required for amino acid biosynthesis from Leptospira interrogans serovar icterohaemorrhagiae. Richaud, C., Margarita, D., Baranton, G., Saint Girons, I. J. Gen. Microbiol. (1990) [Pubmed]
  15. Genetic manipulation of a primary metabolic pathway for L: -ornithine production in Escherichia coli. Lee, Y.J., Cho, J.Y. Biotechnol. Lett. (2006) [Pubmed]
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