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Query: UNIPROT:P06889 (Mol)
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Primary leaves of 7- to 9-day-old Red Mexican bean plants were inoculated with virulent or avirulent isolates of Pseudomonas syringae pv. phaseolicola, or saprophytic P. fluorescens either by vacuum infiltration of the whole leaf lamina, or by syringe-inoculation of selected leaf panels. In the incompatible combination, resistance was associated with a hypersensitive response (HR). Syringe-inoculated leaves were sampled in three zones: zone 1, the inoculated leaf area; zone 2, the surrounding 0.5-0.7 cm of leaf tissue; and zone 3, the remainder of the leaf. Northern blots of RNA from zones 1, 2, and 3 were probed with bean cDNAs for phenylalanine ammonia-lyase (PAL), chalcone synthase (CHS), chitinase (CHT), and lipoxygenase (LOX). Accumulation of PAL, CHS, and CHT transcripts was more rapid and generally of greater magnitude in the incompatible than in the compatible interaction and, in both cases, was observed essentially only in zone 1 tissues. Similarly, antibacterial phytoalexins were only detected in zone 1 from the incompatible interaction. Young primary leaves have a background level of LOX transcripts, which declines as leaves age. This decline was accelerated over the first 12 hr postinoculation (hpi) with avirulent bacteria, whereas a weak transient induction, peaking at 5-6 hpi, was observed in the compatible interaction. A subsequent, strong accumulation of LOX transcripts was seen in both the compatible and incompatible interactions outside the inoculation site starting about 14 hpi. LOX transcripts did not accumulate at the inoculation site itself in the incompatible interaction compared to a relatively strong induction in the compatible interaction. Interestingly, inoculation of leaves with cells of the saprophyte P. fluorescens also induced the accumulation of transcripts for CHS, CHT, and LOX, but generally to a lesser degree than in the incompatible interaction. No HR occurred and no macroscopic cell damage was apparent in leaves inoculated with P. fluorescens. However, at the microscopic level individual, trypan blue-stained, necrotic plant cells were visible. In spite of this and the accumulation of CHS transcripts, no phytoalexin accumulation was found up to 48 hr after inoculation. The spatial and temporal relationship of the hypersensitive reaction to defense gene transcript and phytoalexin accumulation is discussed.
Mol Plant Microbe Interact
PMID:Spatial and temporal accumulation of defense gene transcripts in bean (Phaseolus vulgaris) leaves in relation to bacteria-induced hypersensitive cell death. 840 Mar 75

An acidic chitinase (SE) was found to accumulate in leaves of sugar beet (Beta vulgaris) during infection with Cercospora beticola. Two isoforms, SE1 and SE2, with MW of 29 kDa and pI of approximately 3.0 were purified to homogeneity. SE2 is an endochitinase that also exhibits exochitinase activity, i.e., it is capable of hydrolyzing chito-oligosaccharides, including chitobiose, into N-acetyl-glucosamine. Partial amino acid sequence data for SE2 were used to obtain a cDNA clone by polymerase chain reaction. The clone was used to isolate a cDNA clone encoding SE2. The deduced amino acid sequence for SE2 is 58-67% identical to the class III chitinases from cucumber, Arabidopsis, and tobacco. A transient induction of SE2 mRNA during the early stages of infection with C. beticola is much stronger in tolerant plants than in susceptible plants. Transgenic tobacco (Nicotiana benthamiana) plants constitutively accumulate SE2 protein in the intercellular space of their leaves. In a preliminary infection experiment, the transgenic plants did not show increase in resistance against C. nicotianae.
Mol Plant Microbe Interact
PMID:An acidic class III chitinase in sugar beet: induction by Cercospora beticola, characterization, and expression in transgenic tobacco plants. 840 Mar 78

The occurrence of chitin in the eggshell of Heligmosomoides polygyrus has been determined by histochemical and biochemical techniques. Approximately 5% of the egg dry weight was chitin. Staining with Calcofluor white showed the chitin in the eggshell to be more accessible to the stain after hatching or rupturing of the eggshell. Chitinolytic activity has been detected using fluorescent substrates in extracts of adult males (at low levels), females and eggs. Enzyme activity in situ, within the developing larvae, was visualised with the same substrates. It was localized in discrete granules about 1 micron in diameter which occurred as groups in areas of about 5 microns in diameter, in the posterior third of the larvae. The chitinolytic activity in the eggs increased with the age of the egg and was released into the medium when the eggs hatched. The chitinase activities were very sensitive to inhibition by allosamidin, a specific chitinase inhibitor, with an IC50 for the crude egg extract of 2.2 nM. However, treatment of eggs with 250 microM allosamidin resulted in a slowing but not cessation of egg hatching.
Mol Biochem Parasitol 1993 Apr
PMID:Chitinolytic activities in Heligmosomoides polygyrus and their role in egg hatching. 847 56

Over the last 10 years considerable progress has been made in the immunological and biochemical characterization of oviduct-specific glycoproteins. It is now well established that a subclass of these secretory products, designated as oviductins, associate with the zona pellucida of the ovulated oocyte and with the early embryo. Recent reports on the cloning of cDNAs of oviductins from various species, including that of golden hamster (Mesocricetus auratus) oviductin by our laboratory, allowed us to compare their deduced amino acid sequences with those of other proteins. Optimal alignment analysis showed that oviductins contain regions of significant similarity with catalytically inactive mammalian members of the bacterial and microfilarial chitinase protein family. Most importantly, a close examination of the hamster and human deduced amino acid sequences revealed that both glycoproteins possess contiguous Ser/Thr rich repeated units, clustered in their carboxy-terminal portions. These mucin-type motifs are similar in the hamster and human glycoprotein, although hamster oviductin contains more of these complete units. This striking feature might indicate that these molecules play a similar role to mucin-type glycoproteins, e.g., in protecting the oocyte and early embryo against attacks from their environment. We propose a model whereby oviductins are targeted to the oocyte via the interaction of their chitinase-like domains with specific oligosaccharide moieties of the zona pellucida. Once localized to this structure, oviductin molecules would act as a protective shield around the oocyte and early embryo by virtue of their densely glycosylated mucin-type domains.
Mol Reprod Dev 1995 Jul
PMID:Oviductins possess chitinase- and mucin-like domains: a lead in the search for the biological function of these oviduct-specific ZP-associating glycoproteins. 858 39

A new basic chitinase gene, designated RC24, was isolated from a rice genomic library. The predicted RC24 protein contains 322 amino acid residues and exhibits 68% to 95% amino acid identity with known class I rice chitinases. RC24 protein expressed in Escherichia coli exhibited chitinase activity and strongly inhibited bacterial growth. Two transcription start sites of the RC24 gene were mapped by primer extension analysis of both rice native RNA and in vitro transcribed RNA using a RC24 promoter/GUS (beta-glucuronidase) gene fusion as a template. The 5'-flanking region of RC24 contained several putative stress-responsive cis-acting elements. A basal level of RC24 transcripts was detected in rice root and stem tissues, but not in leaf tissues. RC24 transcripts rapidly accumulated within 1 h after fungal elicitor treatment of suspension-cultured cells, and the levels continued to increase for at least 9 h. RC24 transcript accumulation was also observed in intact leaf tissues upon wounding, Transgenic rice plants containing the RC24/GUS gene fusion further confirmed that the RC24 gene showed a tissue-specific expression pattern and that transcription of the RC24 propmoter was sensitively and rapidly activated by wounding.
Plant Mol Biol 1996 Feb
PMID:Regulation, expression and function of a new basic chitinase gene in rice (Oryza sativa L.). 860 93

Genes that are expressed during leaf senescence in Brassica napus were identified by the isolation of representative cDNA clones. DNA sequence and deduced protein sequence from two senescence-related cDNAs, LSC94 and LSC222, representing genes that are expressed early in leaf senescence before any yellowing of the leaves is visible, showed similarities to genes for pathogenesis-related (PR) proteins: a PR-1a-like protein and a class IV chitinase, respectively. The LSC94 and LSC222 genes showed differential regulation with respect to each other; an increase in expression was detected at different times during development of healthy leaves. Expression of both genes was induced by salicylic acid treatment. These findings suggest that some PR genes, as well as being induced by pathogen infection, may have alternative functions during plant development, for example in the process of leaf senescence.
Plant Mol Biol 1996 Feb
PMID:Leaf senescence in Brassica napus: expression of genes encoding pathogenesis-related proteins. 860 8

A gene (pMON9617; Chi2;1) identified by screening a tomato pistil cDNA library has been found to encode a protein similar in sequence to class II chitinases. Using a baculovirus expression system we show that the Chi2;1 protein is an active endochitinase. The Chi2;1 protein is most similar in sequence to a previously described stylar chitinase (SK2) isolated from potato. Both proteins lack the diagnostic N-terminal cysteine-rich regions and the C-terminal vacuolar targeting signals of class I chitinases and appear to define a novel type of class II endochitinases associated with flowers. Chi2;1 is expressed predominantly in floral organs and its expression within these organs is temporally regulated. The highest level of expression is found in the transmitting tissue of the style where Chi2;1 mRNA begins to accumulate just prior to anthesis. In vegetative tissue, low levels of Chi2;1 mRNA were detected, and these levels did not increase in response to wounding or treatment with ethephon. mRNA from Chi2;1 orthologs was not detected in most other angiosperms tested, even including some members of the Solanaceae, and it is therefore unlikely that Chi2;1 is essential for stylar function. A fragment containing 1.4 kilobase pairs of 5'-flanking DNA from the Chi2;1 gene was shown to drive high-level expression of an attached reporter gene in the styles of transgenic tomatoes. This fragment has utility for engineering expression of other coding regions in styles.
Plant Mol Biol 1996 Mar
PMID:An endochitinase gene expressed at high levels in the stylar transmitting tissue of tomatoes. 863 49

An acidic beta-1,3-glucanase was detected in cucumber leaves inoculated with either Colletotrichum lagenarium or tobacco necrosis virus (TNV) as well as in the leaves above those inoculated with the pathogens. The enzyme is extracellular and migrates in native polyacrylamide gel electrophoresis (PAGE) together with a Class III chitinase, a bifunctional chitinase/lysozyme. The beta-1,3-glucanase was separated by ultra-narrow pH range IEF-PAGE or by SDS_PAGE and was purified to apparent homogeneity. Only one isoform of the enzyme was detected. Its apparent molecular mass in 38 kDa as estimated by SDS-PAGE, its isoelectric point is 3.6 and the specific activity is approximately 26 micromol glucose equivalents liberated from laminarin min(-1)mg(-1) protein. Partial amino acid (five peptide fragments with a total of 65 amino acids) sequencing of the beta-1,3-glucanase revealed similarities of 49% to 72% to sequences of published beta-1,3-glucanases from tobacco, tomato, soybean, barley, and rice plants. A time course study indicated that the increase of the beta-1,3-glucanase activity was associated with induced resistance against C. lagenarium. The implications of these results to coordinate defense responses in plant-microbe interactions are discussed.
Mol Plant Microbe Interact
PMID:Purification and characterization of an acidic beta-1,3-glucanase from cucumber and its relationship to systemic disease resistance induced by Colletotrichum lagenarium and tobacco necrosis virus. 866

NaCl (428 mM)-adapted tobacco (Nicotiana tabacum L. var Wisconsin 38) cells accumulate and secrete several antifungal chitinases. The predominant protein secreted to the culture medium was a 29-kD peptide that, based on internal amino acid sequence, was determined to be a class II acidic chitinase with similarity to PR-Q. The four predominant chitinases (T1, T2, T3, and T4) that accumulated intracellularly in 428 mM NaCl-adapted cells were purified. Based on N-terminal sequence analyses, two of these were identified as class I chitinase isoforms, one similar to the N. tomentosiformis (H. Shinshi, J.M. Neuhaus, J. Ryals, F. Meins [1990] Plant Mol Biol 14:357-368) protein (T1) and the other homologous to the N. sylvestris (Y. Fukuda, M. Ohme, H. Shinshi [1991] Plant Mol Biol 16:1-10) protein (T2). The other two proteins (T3 and T4) were determined to be novel chitinases that have sequence similarity with class I chitinases, but each lacks a chitin-binding domain. All four chitinases inhibited Fusarium oxysporum f. sp. lycopersici and Trichoderma longibrachiatum hyphal growth in vitro, although the isoforms containing a chitin-binding domain were somewhat more active. Conditions were established for the successful expression of soluble and active bacterial recombinant T2. Expression of soluble recombinant T2 was achieved when isopropyl beta-D-thiogalactopyranoside induction occurred at 18 degrees C but not at 25 or 37 degrees C. The purified recombinant protein exhibited antifungal activity comparable to a class I chitinase purified from NaCl-adapted tobacco cells.
 ...
PMID:Novel osmotically induced antifungal chitinases and bacterial expression of an active recombinant isoform. 875 2

To characterize the acidic endochitinase EP3, able to rescue somatic embryos of the carrot cell line ts11, the enzyme was purified from the medium of wild-type suspension cultures. Peptide sequences, deduced amino acid sequences of corresponding PCR-generated cDNA clones, serological relation and biochemical properties showed that there were at least five closely related chitinases, four of which could be identified as class IV EP3 chitinases with an apparent size of 30 kDa. Two other proteins were identified as a serologically related class I acidic chitinase (DcChitI) of 34 kDa, and a serologically unrelated 29 kDa class II acidic chitinase (DcChitII), respectively. Additional cDNA sequences, Western and Southern analysis showed the presence of a least two, but possibly more, highly homologous class IV EP3 genes in the carrot genome. Two class IV EP3 chitinases were tested and found to be able to increase the number of ts11 globular embryos formed under non-permissive conditions. One of the class IV EP3 chitinases as well as the class I chitinase DcChitI promoted the transition from globular to heart-stage ts11 embryos. The class II endochitinase and a heterologous class IV chitinase from sugar-beet were not active on ts11. This suggests that there are differences in the specificity of chitinases in terms of their effect on plant somatic embryos.
Plant Mol Biol 1996 Jun
PMID:Characterization of chitinases able to rescue somatic embryos of the temperature-sensitive carrot variant ts 11. 879 Feb 95


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