A new type of plant chitinase containing LysM domains from a fern (Pteris ryukyuensis): roles of LysM domains in chitin binding and antifungal activity.
Chitinase-A (PrChi-A), of molecular mass 42 kDa, was purified from the leaves of a fern (P. ryukyuensis) using several column chromatographies. The N-terminal amino acid sequence of PrChi-A was similar to the lysin motif (LysM). A cDNA encoding PrChi-A was cloned by rapid amplification of cDNA ends and polymerase chain reaction. It consisted of 1459 nucleotides and encoded an open-reading frame of 423-amino-acid residues. The deduced amino acid sequence indicated that PrChi-A is composed of two N-terminal LysM domains and a C-terminal catalytic domain, belonging to the group of plant class IIIb chitinases, linked by proline, serine, and threonine-rich regions. Wild-type PrChi-A had chitin-binding and antifungal activities, but a mutant without LysM domains had lost both activities. These results suggest that the LysM domains contribute significantly to the antifungal activity of PrChi-A through their binding activity to chitin in the cell wall of fungi. This is the first report of the presence in plants of a family-18 chitinase containing LysM domains.
Onaga
Shoko
S
Department of Bioscience and Biotechnology, Faculty of Agriculture, Ryukyu University, Okinawa 903-0213, Japan.
Taira
Toki
T
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000935:Antifungal Agents / Q000737:chemistry* / Q000302:isolation & purification; D001483:Base Sequence; D001665:Binding Sites; D020134:Catalytic Domain; D002686:Chitin / Q000378:metabolism*; D002688:Chitinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D006868:Hydrolysis; D008969:Molecular Sequence Data; D009088:Mucoproteins / Q000737:chemistry*; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D032495:Pteris / Q000201:enzymology*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D000935:Antifungal Agents; D018076:DNA, Complementary; D009088:Mucoproteins; D010940:Plant Proteins; D011994:Recombinant Proteins; C010393:lysin, gastropoda; D002686:Chitin; D002688:Chitinases