Evidence for a third structural class of beta -1,3-glucanase in tobacco

Glucan endo-1,3-beta-glucosidases beta-1,3-glucanases) have been implicated in several developmental processes and they may also play a direct role in the plant's defense against fungal pathogens. In an effort to characterize the glucanase gene family, complementary DNA clones encoding an acidi...

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Bibliographic Details
Published in:Plant molecular biology 1990-12, Vol.15 (6), p.797-808
Main Authors: Payne, G, Ward, E, Gaffney, T, Goy, P.A, Moyer, M, Harper, A, Meins, F. Jr, Ryals, J
Format: Article
Language:English
Subjects:
Amino Acid Sequence
amino acid sequences
Base Sequence
beta-glucanase
Biological and medical sciences
cdna
Cellulase - biosynthesis
Cellulase - chemistry
Cellulase - genetics
Chitinases - genetics
cloning
ddbj/x54456
DNA
DNA - genetics
embl/x54456
enzyme activity
Escherichia coli
Extracellular Space - enzymology
Fundamental and applied biological sciences. Psychology
genbank/x54456
gene expression
genes
Genes, Plant
Genes. Genome
glucan endo-1,3-beta-glucosidase
high performance liquid chromatography
infection
leaves
Molecular and cellular biology
Molecular genetics
Molecular Sequence Data
Molecular Structure
Mosaic Viruses - physiology
Nicotiana - enzymology
Nicotiana - genetics
Nicotiana tabacum
Northern blotting
nucleotide sequences
pathogenesis-related proteins
Plant Proteins - biosynthesis
Plant Proteins - genetics
Plants, Toxic
prediction
Protein Processing, Post-Translational
Recombinant Proteins - biosynthesis
Sequence Homology, Nucleic Acid
Southern blotting
Tobacco mosaic virus
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Summary:Glucan endo-1,3-beta-glucosidases beta-1,3-glucanases) have been implicated in several developmental processes and they may also play a direct role in the plant's defense against fungal pathogens. In an effort to characterize the glucanase gene family, complementary DNA clones encoding an acidic form of beta-1,3-glucanase have been isolated from tobacco. The cDNA was expressed in E. coli and shown to encode a beta-1,3-glucanase activity. The protein sequence encoded by the cDNA was found to match the partial protein sequence of PR-35, a previously characterized beta-1,3-glucanase [29]. The protein encoded by the cDNA was purified from the extracellular fluid of TMV-infected tobacco leaves and found by immunological methods to correspond to glucanase PR-Q' [10]. From a detailed analysis of the cDNA it is clear that this glucanase represents a third structural class of enzyme which differs substantially from both the basic, vacuolar glucanase and the acidic, extracellular forms (PR-2, PR-N and PR-O). It has previously been demonstrated that the basic form of beta-1,3-glucanase is synthesized as a pre-pro-enzyme and upon maturation the 21 amino acid signal peptide and a 22 amino acid carboxy-terminal peptide are removed. This processing event has been proposed to be involved with the vacuolar localization of the enzyme. By comparing the deduced protein structure of PR-Q' to that of the basic form it is evident that this extracellular enzyme is missing the carboxy-terminal 22 amino acids. The role of a conserved phenylalanine-glycine dipeptide in the processing of glucanases and other pathogenesis-related proteins from tobacco is discussed.
ISSN:0167-4412
1573-5028
DOI:10.1007/BF00039420