type I phosphomannose isomerase in eukaryotes and bacteria, N-terminal cupin domain
This subfamily contains type I phosphomannose isomerase (PMI; E.C. 5.3.1.8; also known as mannose-6-phosphate isomerase) found in eukaryotes and some bacteria such as Salmonella enterica. PMI catalyzes the reversible isomerization of fructose-6-phosphate (F6P) and mannose-6-phosphate (M6P), the first committed step in the synthesis of mannosylated glycoproteins. The active site, located within the N-terminal jelly roll-like beta-barrel cupin fold, contains a single essential zinc atom and forms a deep, open cavity large enough to contain M6P or F6P. PMI type I also has a C-terminal beta-barrel fold which has diverged considerably from the N-terminal domain and is not included here. This subfamily contains an alpha helical domain that is found in eukaryotic and some prokaryotic PMIs but is not present in their archaeal counterparts. F6P is a substrate for glycolysis and gluconeogenesis, while M6P is a substrate for production of activated mannose donor guanosine 5'-diphosphate D-mannose, an important precursor of mannosylated biomolecules such as glycoproteins, bacterial exopolysaccharides and fungal cell wall components. PMI is also essential for survival, virulence and possibly pathogenicity of some bacteria and protozoan parasites, as well as for cell wall integrity of certain yeasts. Thus, PMI is a potential target against fungal infections causing serious illness or death.
Feature 1: metal binding site [ion binding site], 4 residue positions
Conserved feature residue pattern:[QH] H E H
Evidence:
Comment:The four-coordinate metallocenter usually includes three histidines and one glutamate; however, proteins in this subfamily may bind metal via different amino acids
Jiyao W et al.(2023). "The conserved domain database in 2023.",