Chitinase

About: Chitinase is a research topic. Over the lifetime, 4690 publications have been published within this topic receiving 161786 citations. The topic is also known as: 1,4-beta-poly-N-acetylglucosaminidase & poly-beta-glucosaminidase.

Binding of the Magnaporthe oryzae Chitinase MoChia1 by a Rice Tetratricopeptide Repeat Protein Allows Free Chitin to Trigger Immune Responses.

Abstract: To defend against pathogens, plants have developed complex immune systems, including plasma membrane receptors that recognize pathogen-associated molecular patterns, such as chitin from fungal cell walls, and mount a defense response. Here, we identify a chitinase, MoChia1 (Magnaporthe oryzae chitinase 1), secreted by M. oryzae, a fungal pathogen of rice (Oryza sativa). MoChia1 can trigger plant defense responses, and expression of MoChia1 under an inducible promoter in rice enhances its resistance to M. oryzae. MoChia1 is a functional chitinase required for M. oryzae growth and development; knocking out MoChia1 significantly reduced the virulence of the fungus, and we found that MoChia1 binds chitin to suppress the chitin-triggered plant immune response. However, the rice tetratricopeptide repeat protein OsTPR1 interacts with MoChia1 in the rice apoplast. OsTPR1 competitively binds MoChia1, thereby allowing the accumulation of free chitin and re-establishing the immune response. Overexpressing OsTPR1 in rice plants resulted in elevated levels of reactive oxygen species during M. oryzae infection. Our data demonstrate that rice plants not only recognize MoChia1, but also use OsTPR to counteract the function of this fungal chitinase and regain immunity.

Effect of plant and microbial chitinases on the eggs and juveniles of Meloidogyne hapla Chitwood (Nematoda: Tylenchida)

Abstract: Chitinases from Phaseolus vulgaris, Serratia marcescens and Streptomyces griseus were compared for their effects on eggs and juveniles of Meloidogyne hapla Chitwood. Increased hatch rates of nematode eggs were observed on incubation with chitinase from all three sources. After treatment with chitinases from S. marcescens and St. griseus many of the eggs remaining became spherical with a concomitant increase in the number of dead juveniles. Egg mortality was observed with purified P. vulgaris chitinase at concentrations of 17 μg protein/ml and above. The results suggest that exogenous chitinases cause premature hatch of nematode eggs and could be used as an aid in the control of nematodes.

Characterization of two antifungal endochitinases from barley grain

Abstract: A basic chitinase (chitinase T, EC 3.2.1.14, molecular mass 33 kDa, pI 9.8) was isolated and compared with a previously described chitinase (chitinase C, molecular mass 28 kDa, pI 9.7). The two chitinases were isolated in homogeneous form from barley (Hordeum vulgare L.) Bomi mutant 1508 grains either by two cation exchange steps or by one affinity step followed by cation exchange. Both chitinases are endochitinases with specific activities of 168 and 54 nkat (mg protein)−1 for chitinase T and chitinase C, respectively. Both inhibit the growth of Trichoderma viride efficiently. The lysozyme activity of both chitinases is 104 times lower than that of hen egg-white lysozyme as measured by lysis of cell walls of Micrococcus lysodeikticus. The amino acid composition and two partial amino acid sequences of chitinase T were determined. A 23 residue sequence of the N-terminal domain of chitinase T, which was not present in chitinase C, showed 73% identity with domain B of wheat germ lectin and 65% identity with the N-terminal domain of an endochitinase from bean leaves (deduced from cDNA). A 9 amino acid sequence of a cyanogen bromide fragment of chitinase T was identical with a cDNA deduced sequence of a barley aleurone endochitinase but differed in one residue from chitinase C. Generally, the two grain chitinases have physico-chemical and enzymatic properties similar to the plant leaf chitinases characterized. Both chitinases are localized in the aleurone layer and starchy endosperm of developing and germinating grain, but not in the embryo. The appearance of chitinases T and C at a late state of grain development suggests a role for these enzymes as a defense against fungi in the quiescent and germinating grain.

Characterization of a novel cis-acting element that is responsive to a fungal elicitor in the promoter of a tobacco class I chitinase gene.

Abstract: The expression of tobacco class I chitinase gene is effectively induced by a fungal elicitor in suspension-cultured tobacco cells. To identify cis-acting DNA elements that respond to the elicitor, a series of promoter constructs of the chitinase gene CHN50 fused to β-glucuronidase gene was introduced into tobacco cultured cells. Promoter deletion analysis of the chitinase gene CHN50 in transgenic tobacco calli indicated that the DNA region between positions -788 and -345 from the start site of transcription is required for inducibility by the elictor. A gel mobility shift assay revealed that nuclear factor(s) specifically interacted with the DNA region between positions -574 and -476. Moreover, this novel DNA-binding activity was present in nuclear extracts prepared from elicitor-treated cultured cells but not in extracts from untreated cells. Competitive binding assays and methylation interference experiments showed that the nuclear factor(s) bound specifically to a sequence of 22 bp that extended from positions -539 to -518 and contained a direct repeat of GTCAG spaced by three nucleotides. This motif is a candidate for a cis-acting elicitor-responsive element (EIRE) that is involved in the transcription of the class I chitinase gene.