[BjCHI1 from Brassica juncea displays both chitinase and agglutination activity].
The proteins encoded by the Brassica juncea chitinase gene BjCHI1 and its derived genes BjCHI2 and BjCHI3 were expressed by Multi-copy Pichia expression system. The chitinase activity of FPLC purified BjCHI1, BjCHI2 and BjCHI3 were tested and the results showed that all the three proteins degraded both CM-chitin-RBV and colloidal chitin. The Km values of BjCHI1, BjCHI2 and BjCHI3 for CM-chitin-RBV were estimated as 0.799 mg/mL, 0.544 mg/mL and 0.793 mg/mL, respectively. When the colloidal chitin was used as substrate, the Km values were 0.281 mg/mL, 0.388 mg/mL and 1.643 mg/mL, respectively, indicating chitin-binding domain can increase affinity of chitinase to insoluble substrate. In the agglutination activity assay, only BjCHI1 shows activity when the protein concentration was more than 33 micrograms/mL, while BjCHI2 and BjCHI3 without agglutination activity even when the concentration was increased as high as 800 micrograms/mL. This means that the two chitin-binding domains in BjCHI1 are essential for agglutination and BjCHI1 is the first protein which shows both chitinase and agglutination activity identified so far in plants.
Ouyang
Shi-Wen
SW
Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
Zhao
Kai-Jun
KJ
Feng
Lan-Xiang
LX
Chye
Mee-Len
ML
Ram
Sathishkvmar
S
D000371:Agglutination; D000373:Agglutinins / Q000235:genetics*; D002688:Chitinases / Q000235:genetics* / Q000302:isolation & purification / Q000502:physiology; D009149:Mustard Plant / Q000737:chemistry*; D010843:Pichia / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics*; D010957:Plasmids; D016133:Polymerase Chain Reaction; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000302:isolation & purification
D000373:Agglutinins; D010940:Plant Proteins; D011994:Recombinant Proteins; D002688:Chitinases