Glycobiology Advance Access originally published online on February 29, 2008
Glycobiology 2008 18(5):414-423; doi:10.1093/glycob/cwn018
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
A new type of plant chitinase containing LysM domains from a fern (Pteris ryukyuensis): Roles of LysM domains in chitin binding and antifungal activity
Department of Bioscience and Biotechnology, Faculty of Agriculture, Ryukyu University, Okinawa 903-0213, Japan
1 To whom correspondence should be addressed: Tel: +81-98-895-8802; Fax: +81-98-895-8802; e-mail: tokey{at}agr.u-ryukyu.ac.jp
Received on October 26, 2007; revised on February 19, 2008; accepted on February 20, 2008
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.
Key words: antifungal activity / chitin binding / family 18 chitinase / LysM/plant chitinase