Carboxy-terminus recruitment induced by substrate binding in eukaryotic fructose bis-phosphate aldolases

Biochemistry. 2007 Aug 21;46(33):9533-40. doi: 10.1021/bi700615r. Epub 2007 Jul 28.

Abstract

The crystal structures of Leishmania mexicana fructose-1,6-bis(phosphate) aldolase in complex with substrate and competitive inhibitor, mannitol-1,6-bis(phosphate), were solved to 2.2 A resolution. Crystallographic analysis revealed a Schiff base intermediate trapped in the native structure complexed with substrate while the inhibitor was trapped in a conformation mimicking the carbinolamine intermediate. Binding modes corroborated previous structures reported for rabbit muscle aldolase. Amino acid substitution of Gly-312 to Ala, adjacent to the P1-phosphate binding site and unique to trypanosomatids, did not perturb ligand binding in the active site. Ligand attachment ordered amino acid residues 359-367 of the C-terminal region (353-373) that was disordered beyond Asp-358 in the unbound structure, revealing a novel recruitment mechanism of this region by aldolases. C-Terminal peptide ordering is triggered by P1-phosphate binding that induces conformational changes whereby C-terminal Leu-364 contacts P1-phosphate binding residue Arg-313. C-Terminal region capture synergizes additional interactions with subunit surface residues, not perturbed by P1-phosphate binding, and stabilizes C-terminal attachment. Amino acid residues that participate in the capturing interaction are conserved among class I aldolases, indicating a general recruitment mechanism whereby C-terminal capture facilitates active site interactions in subsequent catalytic steps. Recruitment accelerates the enzymatic reaction by using binding energy to reduce configurational entropy during catalysis thereby localizing the conserved C-terminus tyrosine, which mediates proton transfer, proximal to the active site enamine.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Alanine / chemistry
  • Alanine / genetics
  • Amino Acid Sequence
  • Amino Acid Substitution
  • Animals
  • Binding Sites
  • Crystallography, X-Ray
  • Enzyme Inhibitors / chemistry
  • Fructose-Bisphosphate Aldolase / antagonists & inhibitors
  • Fructose-Bisphosphate Aldolase / chemistry*
  • Glycine / chemistry
  • Glycine / genetics
  • Leishmania mexicana / chemistry*
  • Mannitol Phosphates / chemistry
  • Molecular Sequence Data
  • Protozoan Proteins / antagonists & inhibitors
  • Protozoan Proteins / chemistry*
  • Rabbits
  • Substrate Specificity

Substances

  • Enzyme Inhibitors
  • Mannitol Phosphates
  • Protozoan Proteins
  • Fructose-Bisphosphate Aldolase
  • Alanine
  • Glycine

Associated data

  • PDB/2QAP
  • PDB/2QDG
  • PDB/2QDH