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Gene Review

tnaA  -  tryptophanase

Escherichia coli O157:H7 str. EDL933

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Disease relevance of tnaA

  • When a tnaA-disrupted E. coli strain expressing the altered cysE gene was transformed with a plasmid carrying the bcr gene, the transformant exhibited more L-cysteine production than cells carrying the vector only [1].
  • The structure shares the same fold with and has similar quaternary structure to Proteus vulgaris tryptophanase and tyrosine-phenol lyase, but is found in a closed conformation when compared with these two enzymes [2].

High impact information on tnaA

  • Rcd increases the affinity of tryptophanase for its substrate tryptophan which causes increased indole production by cells in low-density cultures [3].
  • Furthermore, the stabilization of multicopy plasmids by Rcd is shown to be tryptophanase dependent, and a tryptophanase-deficient strain is resistant to growth inhibition by Rcd overexpression [3].
  • We have identified tryptophanase (which catabolizes tryptophan to pyruvate and indole) as an Rcd binding protein [3].
  • To identify proteins over- or under-expressed in response to E. coli biofilm formation and indole signalling, we compared the proteomes of the E. coli S17-1 wild-type and 3714 (S17-1 tnaA::Tn5) tryptophanase-negative mutant cells (which don't produce indole) grown as suspensions or biofilms in the presence or absence of exogenous indole [4].
  • Pyridoxal 5'-phosphate (PLP) dependent tryptophanase has been isolated from Escherichia coli and its crystal structure has been determined [2].

Biological context of tnaA

  • The tryptophanase structure, solved in its apo form, does not have covalent PLP bound in the active site, but two sulfate ions [2].


  1. Effect of drug transporter genes on cysteine export and overproduction in Escherichia coli. Yamada, S., Awano, N., Inubushi, K., Maeda, E., Nakamori, S., Nishino, K., Yamaguchi, A., Takagi, H. Appl. Environ. Microbiol. (2006) [Pubmed]
  2. Structure of Escherichia coli tryptophanase. Ku, S.Y., Yip, P., Howell, P.L. Acta Crystallogr. D Biol. Crystallogr. (2006) [Pubmed]
  3. Indole signalling contributes to the stable maintenance of Escherichia coli multicopy plasmids. Chant, E.L., Summers, D.K. Mol. Microbiol. (2007) [Pubmed]
  4. Protein expression in Escherichia coli S17-1 biofilms: impact of indole. Collet, A., Vilain, S., Cosette, P., Junter, G.A., Jouenne, T., Phillips, R.S., Di Martino, P. Antonie Van Leeuwenhoek (2007) [Pubmed]
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