R. Pickersgill et al., CRYSTAL-STRUCTURE OF POLYGALACTURONASE FROM ERWINIA-CAROTOVORA SSP. CAROTOVORA, The Journal of biological chemistry, 273(38), 1998, pp. 24660-24664
The crystal structure of the 40-kDa endo-polygalacturonase from Erwini
a carotovora ssp, carotovora was solved by multiple isomorphous replac
ement and refined at 1.9 Angstrom to a conventional crystallographic R
-factor of .198 and R-free of 0.239, This is the first structure of a
polygalacturonase and comprises a 10 turn right-handed parallel beta-h
elix domain with two loop regions forming a ''tunnel like'' substrate-
binding cleft. Sequence conservation indicates that the active site of
polygalacturonase is between these two loop regions, and comparison o
f the structure of polygalacturonase with that of rhamnogalacturonase
A from Aspergillus aculeatus enables two conserved aspartates, presume
d to be catalytic residues, to be identified. An adjacent histidine, i
n accord with biochemical results, is also seen. A similarity in overa
ll electrostatic properties of the substrate-binding clefts of polygal
acturonase and pectate lyase, which bind and cleave the same substrate
, polygalacturonic acid, is also revealed.