PROSITE documentation PDOC00151
Tryptophan synthase alpha chain signature


Tryptophan synthase (EC catalyzes the last step in the biosynthesis of tryptophan: the conversion of indoleglycerol phosphate and serine, to tryptophan and glyceraldehyde 3-phosphate [1,2]. It has two functional domains: one for the aldol cleavage of indoleglycerol phosphate to indole and glyceraldehyde 3-phosphate and the other for the synthesis of tryptophan from indole and serine. In bacteria and plants [3], each domain is found on a separate subunit (α and β chains), while in fungi the two domains are fused together on a single multifunctional protein.

As a signature pattern for the α chain, we selected a conserved region that contains three conserved acidic residues. The first and the third acidic residues are believed to serve as proton donors/acceptors in the enzyme's catalytic mechanism.

Last update:

November 2011 / Pattern revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

TRP_SYNTHASE_ALPHA, PS00167; Tryptophan synthase alpha chain signature  (PATTERN)


1AuthorsCrawford I.P.
TitleEvolution of a biosynthetic pathway: the tryptophan paradigm.
SourceAnnu. Rev. Microbiol. 43:567-600(1989).
PubMed ID2679363

2AuthorsHyde C.C. Miles E.W.
TitleThe tryptophan synthase multienzyme complex: exploring structure-function relationships with X-ray crystallography and mutagenesis.
SourceBiotechnology (N.Y.) 8:27-32(1990).
PubMed ID1366510

3AuthorsBerlyn M.B. Last R.L. Fink G.R.
TitleA gene encoding the tryptophan synthase beta subunit of Arabidopsis thaliana.
SourceProc. Natl. Acad. Sci. U.S.A. 86:4604-4608(1989).
PubMed ID2734310

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