Submitted to: Physiologia Plantarum
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/1998
Publication Date: N/A
Citation: Interpretive Summary: Coffee is a drink consumed by billions of individuals each day and is prepared by extracting coffee seeds. Despite the importance of coffee, little is known about the proteins that are found in the seed that potentially become extracted during preparation of the drink. In this report, the storage proteins that account for most of the protein in the coffee seeds were characterized. They have molecular properties that are the same as those in a family of the major seed storage proteins found in legumes known as 11S storage proteins. Also described in this report are the genes that encode the proteins and the site in the cell where the proteins are accumulated. The information may be useful to scientists interested in improving the quality of coffee.
Technical Abstract: A legumin-like seed protein was purified from the endosperm of coffee (Coffea arabica L. cv. Colombia). The coffee legumin migrates like 11S storage globulins of other species in sucrose gradients. Subunits of coffee legumin have an apparent molecular weight of about 55 kDa after one-dimensional SDS-polyacrylamide gel electrophoresis in the absence of reducing agents. After sufhydryl reduction, polypeptides appear that have apparent molecular weight of 33 kDa and 24 kDa. Two full-length cDNAs were generated from mRNA of developing seeds. They were more than 98% homologous, and had open reading frames of 1,458 and 1,467 bp, respectively. Examination of a 5'-promoter region from a coffee legumin gene revealed a putative legumin-box. Genomic DNA from C. arabica was digested with 6 different restriction endonucleases. After separation of the fragments by electrophoresis, single discrete fragments on DNA blots hybridized strongly to a cDNA probe for the acidic chain. Fragments that hybridized very weakly were also visible. DNA from other species and commercially important cultivars in the genus Coffea produced similar results. Immunocytochemical studies revealed that the majority of legumin was in the large central cell vacuole.