{PDOC00152}
{PS00168; TRP_SYNTHASE_BETA}
{BEGIN}
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* Tryptophan synthase beta chain pyridoxal-phosphate attachment site *
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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.

The beta chain of the  enzyme requires  pyridoxal-phosphate as a cofactor. The
pyridoxal-phosphate group is attached to a lysine residue.   The region around
this lysine residue also contains two histidine residues which are part of the
pyridoxal-phosphate binding  site.    The signature pattern for the tryptophan
synthase beta chain is derived from that conserved region.

-Consensus pattern: [LIVMYAHQ]-x-[HPYNVF]-x-G-[STA]-H-K-x-N-x(2)-[LIVM]-x-
                    [QEH]
                    [K is the pyridoxal-P attachment site]
-Sequences known to belong to this class detected by the pattern: ALL.
-Other sequence(s) detected in Swiss-Prot: NONE.
-Last update: December 2004 / Pattern and text 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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