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].

References