title: Pepper beta-galactosidase 1 (PBG1) plays a significant role in fruit ripening in bell pepper (Capsicum annuum).
abstract: During bell pepper (Capsicum annuum L.) fruit ripening, beta-galactosidase activity increased markedly as compared with other glycosidases. We purified 77.5 kDa exo-1,4-beta-D-galactanase from red bell pepper fruit classified as beta-galactosidase II. A marked decrease in galactose content appeared during fruit ripening, especially in the pectic fraction. The purified enzyme hydrolyzed a considerable amount of galactose residues in this fraction. We isolated bell pepper beta-galactosidase (PBG1) cDNA. This PBG1 protein contained the putative active site, G-G-P-[LIVM]-x-Q-x-E-N-E-[FY], belonging to glycosyl hydrolase family 35. Quantitative RT-PCR revealed that the expression of PBG1 in red fruit was significantly stronger than that from any other tissues. Moreover, expression of PBG1 occurred prior to that of pepper endo-polygalacturonase 1 (PPG1), the major fruit-ripening enzyme. Based on these results, it appears that the hydrolysis of galactose residues in pectic substances is the first event in the ripening process in bell pepper fruit.
authors.affiliation: Graduate School of Agricultural Sciences, Tohoku University, Sendai, Japan. satoshi-ogasawara@aist.go.jp
authors.forename: Satoshi
authors.initials: S
authors.lastname: Ogasawara
authors.forename: Keietsu
authors.initials: K
authors.lastname: Abe
authors.forename: Tasuku
authors.initials: T
authors.lastname: Nakajima
mesh_terms: D002212:Capsicum / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development*; D002241:Carbohydrates / Q000737:chemistry; D002473:Cell Wall / Q000737:chemistry; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000096:biosynthesis / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D005638:Fruit / Q000201:enzymology* / Q000254:growth & development*; D006026:Glycoside Hydrolases / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008958:Models, Molecular; D010368:Pectins / Q000378:metabolism; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D018749:RNA, Plant / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013379:Substrate Specificity; D001616:beta-Galactosidase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*
chemical_list: D002241:Carbohydrates; D018076:DNA, Complementary; D011134:Polysaccharides; D018749:RNA, Plant; D010368:Pectins; D006026:Glycoside Hydrolases; C066350:exo-1,4-beta-galactanase; D001616:beta-Galactosidase