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1pqh
From Proteopedia
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Serine 25 to Threonine mutation of aspartate decarboxylase
Overview
Aspartate decarboxylase, which is translated as a pro-protein, undergoes intramolecular self-cleavage at Gly24-Ser25. We have determined the crystal structures of an unprocessed native precursor, in addition to Ala24 insertion, Ala26 insertion and Gly24-->Ser, His11-->Ala, Ser25-->Ala, Ser25-->Cys and Ser25-->Thr mutants. Comparative analyses of the cleavage site reveal specific conformational constraints that govern self-processing and demonstrate that considerable rearrangement must occur. We suggest that Thr57 Ogamma and a water molecule form an 'oxyanion hole' that likely stabilizes the proposed oxyoxazolidine intermediate. Thr57 and this water molecule are probable catalytic residues able to support acid-base catalysis. The conformational freedom in the loop preceding the cleavage site appears to play a determining role in the reaction. The molecular mechanism of self-processing, presented here, emphasizes the importance of stabilization of the oxyoxazolidine intermediate. Comparison of the structural features shows significant similarity to those in other self-processing systems, and suggests that models of the cleavage site of such enzymes based on Ser-->Ala or Ser-->Thr mutants alone may lead to erroneous interpretations of the mechanism.
About this Structure
1PQH is a Single protein structure of sequence from Escherichia coli with and as ligands. Active as Aspartate 1-decarboxylase, with EC number 4.1.1.11 Full crystallographic information is available from OCA.
Reference
Structural constraints on protein self-processing in L-aspartate-alpha-decarboxylase., Schmitzberger F, Kilkenny ML, Lobley CM, Webb ME, Vinkovic M, Matak-Vinkovic D, Witty M, Chirgadze DY, Smith AG, Abell C, Blundell TL, EMBO J. 2003 Dec 1;22(23):6193-204. PMID:14633979
Page seeded by OCA on Thu Feb 21 14:31:28 2008
Categories: Aspartate 1-decarboxylase | Escherichia coli | Single protein | Abell, C. | Blundell, T L. | Chirgadze, D Y. | Kilkenny, M L. | Lobley, C M.C. | Matak-Vinkovic, D. | Schmitzberger, F. | Smith, A G. | Vinkovic, M. | Webb, M E. | Witty, M. | MLA | NA | Protein self-processing | Pyruvoyl dependent decarboxylase
