GAPDH exposed on human and pneumococcal cell surface is a novel C1q ligand

Abstract

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) catalyzes the oxidative phosphorylation of o-glyceraldehyde 3-phosphate to form 1,3-diphosphoglycerate and is found in both glycolytic and gluconeogenic metabolic pathways. The reaction mechanism of the bacterial and eukaryotic enzyme has been studied in detail and proceeds through a thioester-acyl enzyme intermediate with a cysteine amino acid in the enzyme active site. The S. solfataricus enzyme has relatively high sequence identity (45-50%) to other archaeal GAPDHs. The low sequence similarity between archaeal GAPDHs and enzymes from the two other kingdoms, as well as the difficulty in aligning residues implicated in the catalytic mechanism, have led to the suggestion that archaeal GAPDHs are unrelated to their bacterial and eukaryotic counterparts and show a convergent molecular evolution in the catalytic region of their structure.