title: TrpB2 enzymes are O-phospho-l-serine dependent tryptophan synthases.
abstract: The rapid increase of the number of sequenced genomes asks for the functional annotation of the encoded enzymes. We used a combined computational-structural approach to determine the function of the TrpB2 subgroup of the tryptophan synthase β chain/β chain-like TrpB1-TrpB2 family (IPR023026). The results showed that TrpB2 enzymes are O-phospho-l-serine dependent tryptophan synthases, whereas TrpB1 enzymes catalyze the l-serine dependent synthesis of tryptophan. We found a single residue being responsible for the different substrate specificities of TrpB1 and TrpB2 and confirmed this finding by mutagenesis studies and crystallographic analysis of a TrpB2 enzyme with bound O-phospho-l-serine.
authors.affiliation: Institute of Biophysics and Physical Biochemistry, University of Regensburg , Universitätsstrasse 31, D-93053 Regensburg, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Busch
authors.forename: Chitra
authors.initials: C
authors.lastname: Rajendran
authors.forename: Olga
authors.initials: O
authors.lastname: Mayans
authors.forename: Patrick
authors.initials: P
authors.lastname: Löffler
authors.forename: Rainer
authors.initials: R
authors.lastname: Merkl
authors.forename: Reinhard
authors.initials: R
authors.lastname: Sterner
mesh_terms: D020134:Catalytic Domain; D003001:Cloning, Molecular; D019295:Computational Biology; D003460:Crystallization; D004926:Escherichia coli; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D011487:Protein Conformation; D013379:Substrate Specificity; D016944:Sulfolobus / Q000201:enzymology; D014364:Tryptophan / Q000096:biosynthesis; D014367:Tryptophan Synthase / Q000737:chemistry / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: D014364:Tryptophan; D014367:Tryptophan Synthase