Structural basis of CoA recognition by the Pyrococcus single-domain CoA-binding proteins

Area of Science:

• Biochemistry
• Structural Biology
• Microbiology

Background:

• Single-domain coenzyme A (CoA)-binding proteins are conserved across bacteria, archaea, and some eukaryotes.
• These proteins possess a Rossmann-fold domain, classifying them within the FAD/NAD(P)-binding superfamily.
• Previous work established the CoA-binding capability of a bacterial ortholog (TTHA1899) through structural and calorimetric studies.

Purpose of the Study:

• To determine the crystal structures of archaeal single-domain CoA-binding proteins from Pyrococcus horikoshii (PH1109) and Pyrococcus furiosus (PF0725).
• To elucidate the structural basis of coenzyme A (CoA) binding in these archaeal proteins.
• To compare the CoA-binding mode of archaeal proteins with their bacterial orthologs.

Main Methods:

• X-ray crystallography was employed to determine the structures of PH1109 alone and complexed with CoA, and PF0725 in its CoA-bound form.
• Isothermal titration calorimetry was used in prior studies to confirm CoA interaction.
• Sequence and structural comparisons were performed between archaeal and bacterial orthologs.

Main Results:

• The crystal structures of Pyrococcus proteins (PH1109 and PF0725) complexed with CoA were determined at high resolution (1.65-1.70 Å).
• The Pyrococcus proteins bind CoA with a 1:1 stoichiometry within a groove formed by five loop regions.
• Archaeal and bacterial single-domain CoA-binding proteins share a common CoA-binding mode, although peripheral interacting residues show variability.

Conclusions:

• Archaeal and bacterial single-domain CoA-binding proteins utilize a conserved mechanism for binding coenzyme A (CoA).
• The structural interactions of these proteins with CoA are distinct and more extensive than those observed in succinyl-CoA synthetase.
• Variations in peripheral residues suggest potential fine-tuning of CoA interactions within the conserved binding framework.