Title |
Molecular cloning of a cDNA encoding a (1→4)-β-mannan endohydrolase from the seeds of germinated tomato (Lycopersicon esculentum)
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Published in |
Planta, November 1997
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DOI | 10.1007/s004250050214 |
Pubmed ID | |
Authors |
J. Derek Bewley, Rachel A. Burton, Yukio Morohashi, Geoffrey B. Fincher |
Abstract |
Mannose-containing polysaccharides are widely distributed in cell walls of higher plants. During endosperm mobilization in germinated tomato seeds (1-->4)-beta-mannan endohydrolases (EC 3.2.1.78) participate in the enzymic depolymerization of these cell wall polysaccharides. A cDNA encoding a (1-->4)-beta-mannanase from the endosperm of germinated tomato (Lycopersicon esculentum Mill.) seeds has been isolated and characterized. The amino acid sequence deduced from the 5'-region of the cDNA exactly matches the sequence of the 65 NH2-terminal amino acids determined directly from the purified enzyme. The mature enzyme consists of 346 amino acid residues, it has a calculated M(r) of 38,950 and an isoelectric point of 5.3. Overall, the enzyme exhibits only 28-30% sequence identity with fungal (1-->4)-beta-mannanases, but more highly conserved regions, which may represent catalytic and substrate-binding domains, can be identified. Based on classification of the tomato (1-->4)-beta-mannanase as a member of the family 5 group of glycosyl hydrolases, Glu-148 and Glu-265 would be expected to be the catalytic acid and the catalytic nucleophile, respectively. Southern hybridization analyses indicate that the enzyme is derived from a family of about four genes. Expression of the genes, as determined by the presence of mRNA transcripts in Northern hybridization analyses, occurs in the endosperm of germinated seeds; no transcripts are detected in hypocotyls, cotyledons, roots or leaves. |
Mendeley readers
Geographical breakdown
Country | Count | As % |
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Unknown | 22 | 100% |
Demographic breakdown
Readers by professional status | Count | As % |
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Student > Ph. D. Student | 4 | 18% |
Student > Postgraduate | 3 | 14% |
Student > Doctoral Student | 2 | 9% |
Researcher | 2 | 9% |
Professor | 2 | 9% |
Other | 4 | 18% |
Unknown | 5 | 23% |
Readers by discipline | Count | As % |
---|---|---|
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Biochemistry, Genetics and Molecular Biology | 1 | 5% |
Environmental Science | 1 | 5% |
Immunology and Microbiology | 1 | 5% |
Engineering | 1 | 5% |
Other | 0 | 0% |
Unknown | 4 | 18% |