This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Fazel, A M Articles by Jensen, R A Search for Related Content PubMed PubMed Citation Articles by Fazel, A M Articles by Jensen, R A

 Previous Article  |  Next Article 

J Bacteriol. 1979 June; 138(3): 805-815

Obligatory biosynthesis of L-tyrosine via the pretyrosine branchlet in coryneform bacteria.

ABSTRACT

Species of coryneform bacteria (Corynebacterium glutamicum, Brevibacterium flavum, and B. ammoniagenes) utilize pretyrosine [beta-(1-carboxy-4-hydroxy-2,5-cyclohexadien-1-yl) alanine] as an intermediate in L-tyrosine biosynthesis. Pretyrosine is formed from prephenate via the activity of at least one species of aromatic aminotransferase which is significantly greater with prephenate as substrate than with either phenylpyruvate or 4-hydroxyphenylpyruvate. Pretyrosine dehydrogenase, capable of converting pretyrosine to L-tyrosine, has been partially purified from all three species. Each of the three pretyrosine dehydrogenases is catalytically active with either nicotinamide adenine dinucleotide or nicotinamide adenine dinucleotide phosphate as cofactors. The Km values for nicotinamide adenine dinucleotide phosphate in C. glutamicum and B. flavum are 55 microM and 14.2 microM, respectively, and corresponding Km values for nicotinamide adenine dinucleotide are 350 microM and 625 microM, respectively. The molecular weights of pretyrosine dehydrogenase in C. glutamicum and in B. flavum are both about 158,000, compared with 68,000 moleculr weitht in B. ammoniagenes. In all three species the enzyme is not feedback inhibited by L-tyrosine. Results obtained with various auxotropic mutants, which were used to manipulate internal concentrations of L-tyrosine, suggest that pretyrosine dehydrogenase is expressed constitutively. Pretyrosine dehydrogenase is quite sensitive to p-hydroxymercuribenzoic acid, complete inhibition being achieved at 10 to 25 microM concentrations. This inhibition is readily reversed by thiol reagents such as 2-mercaptoethanol. Coryneform organisms, like species of blue-green bacteria, appear to lack the 4-hydroxyphenylpyruvate pa thway of L-tyrosine synthesis altogether. The loss of pretyrosine dehydrogenase in extracts prepared from a tyrosine auxotroph affirms the exclusive role of pretyrosine dehydrogenase in L-tyrosine biosynthesis. Other reports in the literature, in which the presence in these organisms of prephenate dehydrogenase is described, appear to be erroneous.

This article has been cited by other articles:

• Chavez-Bejar, M. I., Lara, A. R., Lopez, H., Hernandez-Chavez, G., Martinez, A., Ramirez, O. T., Bolivar, F., Gosset, G. (2008). Metabolic Engineering of Escherichia coli for L-Tyrosine Production by Expression of Genes Coding for the Chorismate Mutase Domain of the Native Chorismate Mutase-Prephenate Dehydratase and a Cyclohexadienyl Dehydrogenase from Zymomonas mobilis. Appl. Environ. Microbiol. 74: 3284-3290 [Abstract] [Full Text]  
• Bonner, C. A., Disz, T., Hwang, K., Song, J., Vonstein, V., Overbeek, R., Jensen, R. A. (2008). Cohesion Group Approach for Evolutionary Analysis of TyrA, a Protein Family with Wide-Ranging Substrate Specificities. Microbiol. Mol. Biol. Rev. 72: 13-53 [Abstract] [Full Text]  
• Soutourina, J., Blanquet, S., Plateau, P. (2000). D-Tyrosyl-tRNATyr Metabolism in Saccharomyces cerevisiae. J. Biol. Chem. 275: 11626-11630 [Abstract] [Full Text]