Purification and properties of two chitinolytic enzymes of Serratia plymuthica HRO-C48.
The chitinolytic rhizobacterium Serratia plymuthica HRO-C48 was previously selected as a biocontrol agent of phytopathogenic fungi. One endochitinase (E.C. 3.2.1.14), CHIT60, and one N-acetyl-beta-1,4- D-hexosaminidase (E.C. 3.2.1.52), CHIT100, were purified and characterized. The endochitinase CHIT60, with an apparent molecular mass of 60.5 kDa, had a N-terminal amino acid sequence highly similar to that of chitinases A from Serratia liquefaciens and Serratia marcescens. The enzyme activity had its peak at 55 degrees C and pH 5.4, and increased by more than 20% in the presence of 10 mM Ca(2+), Co(2+) or Mn(2+). Activity was inhibited by 80% in the presence of 10 mM Cu(2+). CHIT100 appeared to be a monomeric enzyme with a molecular mass of 95.6 kDa and a pI of 6.8. Optimal activity was obtained at 43 degrees C and pH 6.6, and decreased by more than 90 % in the presence of 10 mM Co(2+) or Cu(2+). CHIT100 (100 microg ml(-1)) inhibited spore germination and germ tube elongation of the phytopathogenic fungus Botrytis cinerea by 28 % and 31.6 %, respectively. With CHIT60 (100 microg ml(-1)), the effect was more pronounced: 78 % inhibition of of germination and 63.9 % inhibition of germ tube elongation.
Frankowski
J
J
Universität Rostock, Institut für Molekulare Physiologie und Biotechnologie, Mikrobiologie, Gertrudenstrasse 11a, 18051 Rostock, Germany. frankowski@gmx.net
Lorito
M
M
Scala
F
F
Schmid
R
R
Berg
G
G
Bahl
H
H
D000595:Amino Acid Sequence; D020171:Botrytis / Q000187:drug effects; D002688:Chitinases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*; D003001:Cloning, Molecular; D005798:Genes, Bacterial; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D008970:Molecular Weight; D016415:Sequence Alignment; D012705:Serratia / Q000201:enzymology* / Q000235:genetics; D013696:Temperature; D001619:beta-N-Acetylhexosaminidases / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification*
D002688:Chitinases; D001619:beta-N-Acetylhexosaminidases