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Bacterial
tryptophanase, function and biosynthesis regulation
Abstract:
The
review presents description of function and biosynthesis of
tryptophanase. It focuses mainly on the basic regulatory
strategies of tna operon expression. Tryptophanase isolated from several bacterial
species allows to use tryptophan as the only carbon and nitrogen
source. The enzyme is well characterized and its important amino
acid residues are known. The expression of tryptophanase
structural gene, tnaA, is
controlled on the transciption level and includes variety of
strategies operating at the initiation, elongation and termination
steps. The precise mechanism of transcription termiantion
(attenuation) and the inducing role of tryptophan are described in
details. Examples of control mechanisms other than transcription
regulation are briefly mentioned.
1. Introduction.
2. Characteristics of tryptophanase — structure and
function. 3. Tryptophan transport systems. 4. Tryptophan
biosynthesis. 4.1. Control of transcription initiation. 4.2. Control
of transcription termination (attenuation). 4.3. Control of
transcription elongation. 4.4. Other regulatory mechanisms. 5. Summary |
