PROSITE documentation PDOC00149
Serine/threonine dehydratases pyridoxal-phosphate attachment site


Serine and threonine dehydratases [1,2] are functionally and structurally related pyridoxal-phosphate dependent enzymes:

  • L-serine dehydratase (EC and D-serine dehydratase (EC catalyze the dehydratation of L-serine (respectively D-serine) into ammonia and pyruvate.
  • Threonine dehydratase (EC (TDH) catalyzes the dehydratation of threonine into α-ketobutarate and ammonia. In Escherichia coli and other microorganisms, two classes of TDH are known to exist. One is involved in the biosynthesis of isoleucine, the other in hydroxamino acid catabolism.

Threonine synthase (EC is also a pyridoxal-phosphate enzyme, it catalyzes the transformation of homoserine-phosphate into threonine. It has been shown [3] that threonine synthase is distantly related to the serine/ threonine dehydratases.

In all these enzymes, the pyridoxal-phosphate group is attached to a lysine residue. The sequence around this residue is sufficiently conserved to allow the derivation of a pattern specific to serine/threonine dehydratases and threonine synthases.


Some bacterial L-serine dehydratases - such as those from Escherichia coli - are iron-sulfur proteins [4] and do not belong to this family.

Last update:

December 2004 / Pattern and text revised.


Technical section

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

DEHYDRATASE_SER_THR, PS00165; Serine/threonine dehydratases pyridoxal-phosphate attachment site  (PATTERN)


1AuthorsOgawa H. Gomi T. Konishi K. Date T. Nakashima H. Nose K. Matsuda Y. Peraino C. Pitot H.C. Fujioka M.
TitleHuman liver serine dehydratase. cDNA cloning and sequence homology with hydroxyamino acid dehydratases from other sources.
SourceJ. Biol. Chem. 264:15818-15823(1989).
PubMed ID2674117

2AuthorsDatta P. Goss T.J. Omnaas J.R. Patil R.V.
TitleCovalent structure of biodegradative threonine dehydratase of Escherichia coli: homology with other dehydratases.
SourceProc. Natl. Acad. Sci. U.S.A. 84:393-397(1987).
PubMed ID3540965

3AuthorsParsot C.
TitleEvolution of biosynthetic pathways: a common ancestor for threonine synthase, threonine dehydratase and D-serine dehydratase.
SourceEMBO J. 5:3013-3019(1986).
PubMed ID3098560

4AuthorsGrabowski R. Hofmeister A.E.M. Buckel W.
TitleBacterial L-serine dehydratases: a new family of enzymes containing iron-sulfur clusters.
SourceTrends Biochem. Sci. 18:297-300(1993).
PubMed ID8236444

PROSITE is copyrighted by the SIB Swiss Institute of Bioinformatics and distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives (CC BY-NC-ND 4.0) License, see prosite_license.html.


View entry in original PROSITE document format
View entry in raw text format (no links)