{PDOC00151}
{PS00167; TRP_SYNTHASE_ALPHA}
{BEGIN}
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* Tryptophan synthase alpha chain signature *
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Tryptophan synthase (EC 4.2.1.20) 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 (alpha and beta chains),  while  in fungi the two domains are
fused together on a single multifunctional protein.

As a  signature  pattern  for  the alpha 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.

-Consensus pattern: [LIVM]-E-[LIVM]-[GQ]-x-[PALT]-[FYCHTWP]-[STPK]-[DEKY]-
                    [PA]-[LIVMYGK]-[SGALIMY]-[DE]-[GN]
                    [The first E and the second D/E are active site residues]
-Sequences known to belong to this class detected by the pattern: ALL,  except
 for the Sulfolobus solfataricus enzyme which is highly divergent.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: November 2011 / Pattern revised.

[ 1] Crawford I.P.
     "Evolution of a biosynthetic pathway: the tryptophan paradigm."
     Annu. Rev. Microbiol. 43:567-600(1989).
     PubMed=2679363; DOI=10.1146/annurev.mi.43.100189.003031
[ 2] Hyde C.C., Miles E.W.
     "The tryptophan synthase multienzyme complex: exploring
     structure-function relationships with X-ray crystallography and
     mutagenesis."
     Biotechnology (N.Y.) 8:27-32(1990).
     PubMed=1366510
[ 3] Berlyn M.B., Last R.L., Fink G.R.
     "A gene encoding the tryptophan synthase beta subunit of Arabidopsis
     thaliana."
     Proc. Natl. Acad. Sci. U.S.A. 86:4604-4608(1989).
     PubMed=2734310

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