Rice Class III Chitinase Homologues Isolated by Random Cloning of Rice cDNAs

Abstract

We obtained seven kinds of cDNA clones putatively identified as encoding class III chitinases from cDNA libraries constructed from dichlorophenoxyacetic acid (2,4-D)- and benzyl adenine (BA)- treated rice callus. Putative amino acid sequences encoded in these cDNA clones were compared with those of known chitinases of other plants. Two clones coded for homologues that show high similarity to class III chitinases. These clones contained the common glutamic acid at the active site and were classified as true homologues. The other five clones, however, showed relatively low similarity to class III chitinases and their active sites contained aspartic acid instead of glutamic acid. These clones may correspond to relatives of a super family of class III chitinases. The location of the genes coding for these homologues on the rice genome has been determined by genetic linkage analysis with restriction fragment length polymorphism.

Emergence of a subfamily of xylanase inhibitors within glycoside hydrolase family 18

“…The pRIXI clone (GenPept databank; AN: BAA23810.1) is expected to encode a protein of 304 residues with a predicted relative molecular mass of 33 946.8 and a theoretical pI of 9.33 [13]. In order to address the functionality of this potential inhibitor, its cDNA sequence and that of XIP‐I were expressed in conditions similar to those used for the production of active basic chitinase in Pichia pastoris GS115 strain [12], e.g.…”

“…The cDNA clone encoding a putative rice class III chitinase (DNA Data Bank of Japan; AN: D55712 corresponding to the protein AN: BAA23810.1 in the GenPept databank) was a kind gift of T. Sasaki (National Institute of Agrobiological Resources, Tsukba, Japan) [13]. The full-length cDNA encoding XIP-I (GenPept databank; AN: CAD19479.1) was from in house collection [7].…”

“…No XIP‐type protein was so far identified in rice. Among the GH18 sequences isolated from the rice genome [at least 23 – data from the Carbohydrate‐active enzymes database, http://afmb.cnrs-mrs.fr/CAZY/ accessed 11 January 2005)], only two cDNA sequences were shown to encode recombinant proteins having chitinase activity [12] while others were classified as putative rice class III chitinase(s) based on sequence homology only [13]. In particular the (GenPept databank; AN: BAA23810.1) clone shares higher similarity with XIP‐I than with ‘active’ chitinases and was thus selected as a putative rice xylanase inhibitor (pRIXI).…”

A novel class of protein from wheat which inhibits xylanases1

“…niger xylanase 0.080p0.002 Not applicable A. niger xylanasejinhibitor 0.017p0.002 79p3 A. niger xylanasejPronase-digested inhibitor 0.069p0.005 14p6 A. niger xylanasejPronase/subtilisin-digested inhibitor 0.076p0.008 None extraction conditions used were not optimal. Using a BLASTP (Version 2.0.6) search [16], the N-terminal sequence of the inhibitors showed 86 % identity with the sequence AAGKTGQ-MTVFWGRN, of chitinase III from rice, Oryza sati a [17]. This sequence is probably at or close to the N-terminus of the mature chitinase, as there is a consensus sequence [18] for a cleavable signal sequence downstream from it.…”

Structure, Heterologous Expression, and Properties of Rice (Oryza sativaL.) Family 19 Chitinases

“…Nucleotides were sequenced as described 22) or using an ABI377 DNA sequencer with Big-dye primer and Big-Dye terminator sequencing kits (Applied Biosystems, Foster City, CA, USA). Amino acid and DNA sequences were analyzed using the Clustal W and Blast programs at the DDJB (http://www.ddbj.nig.ac.jp).…”