The pro-form of Stereum purpureum endopolygalacturonase I is inactivated by a pro-sequence in the C-terminal region.
The Pro-form (Pro-EndoPG I) of Stereum purpureum endopolygalacturonase I has a unique C-terminal region (pro-sequence) that is lacking in PGs of other origins. Mature EndoPG I purified from the culture filtrate of this fungus does not have the 44-amino-acid pro-sequence present in Pro-EndoPG I. We expressed Pro-EndoPG I in Escherichia coli and examined its activity. It was found that Pro-EndoPG I had no PG activity, but that PG activity was acquired after the degradation of part of the pro-sequence with V8 protease. These results suggest that the pro-sequence inactivates auto-PG activity. No similar characteristic has been reported for any glycoside hydrolase. We then constructed EndoPG I mutants and identified two Glu residues, E364 and E366, that were related to auto-inactivation. A test involving injection of the enzyme into apple trees showed that Pro-EndoPG I induced the same silver-leaf symptoms as mature EndoPG I.
Ogawa
Shun
S
Faculty of Agriculture and Life Science, Hirosaki University, Hirosaki, Aomori, Japan.
Shimizu
Tetsuya
T
Kimura
Tsubasa
T
Utoh
Kazunori
K
Okuno
Toshikatsu
T
Miyairi
Kazuo
K
D001487:Basidiomycota / Q000201:enzymology*; D004792:Enzyme Precursors / Q000737:chemistry* / Q000235:genetics; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D027845:Malus / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology*; D011096:Polygalacturonase / Q000037:antagonists & inhibitors* / Q000737:chemistry* / Q000235:genetics; D017384:Sequence Deletion; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000235:genetics
D004792:Enzyme Precursors; D005656:Fungal Proteins; D011096:Polygalacturonase; D012697:Serine Endopeptidases; C028344:glutamyl endopeptidase