1S5W

Crystal Structure Analysis of a mutant of DIHYDRODIPICOLINATE SYNTHASE--residue Tyr133 to Phe133

Summary for 1S5W

• Entry DOI: 10.2210/pdb1s5w/pdb
• Related: 1DHP 1S5T 1S5V
• Descriptor: Dihydrodipicolinate synthase (2 entities in total)
• Functional Keywords: synthase, dihydrodipicolinate, lyase
• Biological source: Escherichia coli
• Cellular location: Cytoplasm: P0A6L2
• Total number of polymer chains: 2
• Total formula weight: 62577.87

Authors

Dobson, R.C.J.,Valegard, K.,Gerrard, J.A. (deposition date: 2004-01-21, release date: 2004-04-27, Last modification date: 2023-10-25)

Primary citation

Dobson, R.C.J.,Valegard, K.,Gerrard, J.A.
The Crystal Structure of Three Site-directed Mutants of Escherichia coli Dihydrodipicolinate Synthase: Further Evidence for a Catalytic Triad
J.MOL.BIOL., 338:329-339, 2004

PubMed Abstract: Dihydrodipicolinate synthase (DHDPS, EC 4.2.1.52) catalyses the branchpoint reaction of lysine biosynthesis in plants and microbes: the condensation of (S)-aspartate-beta-semialdehyde and pyruvate. The crystal structure of wild-type DHDPS has been published to 2.5A, revealing a tetrameric molecule comprised of four identical (beta/alpha)(8)-barrels, each containing one active site. Previous workers have hypothesised that the catalytic mechanism of the enzyme involves a catalytic triad of amino acid residues, Tyr133, Thr44 and Tyr107, which provide a proton shuttle to transport protons from the active site to solvent. We have tested this hypothesis using site-directed mutagenesis to produce three mutant enzymes: DHDPS-Y133F, DHDPS-T44V and DHDPS-Y107F. Each of these mutants has substantially reduced activity, consistent with the catalytic triad hypothesis. We have determined each mutant crystal structure to at least 2.35A resolution and compared the structures to the wild-type enzyme. All mutant enzymes crystallised in the same space group as the wild-type form and only minor differences in structure are observed. These results suggest that the catalytic triad is indeed in operation in wild-type DHDPS.

PubMed: 15066435
DOI: 10.1016/j.jmb.2004.02.060

Experimental method

X-RAY DIFFRACTION (2.32 Å)