A family of at least seven beta-galactosidase genes is expressed during tomato fruit development.
During our search for a cDNA encoding beta-galactosidase II, a beta-galactosidase/exogalactanase (EC 3.2.1.23) present during tomato (Lycopersicon esculentum Mill.) fruit ripening, a family of seven tomato beta-galactosidase (TBG) cDNAs was identified. The shared amino acid sequence identity among the seven TBG clones ranged from 33% to 79%. All contained the putative active site-containing consensus sequence pattern G-G-P-[LIVM]-x-Q-x-E-N-E-[FY] belonging to glycosyl hydrolase family 35. Six of the seven single-copy genes were mapped using restriction fragment length polymorphisms of recombinant inbred lines. RNA gel-blot analysis was used to evaluate TBG mRNA levels throughout fruit development, in different fruit tissues, and in various plant tissues. RNA gel-blot analysis was also used to reveal TBG mRNA levels in fruit of the rin, nor, and Nr tomato mutants. The TBG4-encoded protein, known to correspond to beta-galactosidase II, was expressed in yeast and exo-galactanase activity was confirmed via a quantified release of galactosyl residues from cell wall fractions containing beta(1-->4)-D-galactan purified from tomato fruit.
Smith
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DL
Horticultural Crops Quality Laboratory, Agricultural Research Service, United States Department of Agriculture, Building 002, 10300 Baltimore Avenue, Beltsville, Maryland 20705-2350, USA.
Gross
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KC
D000595:Amino Acid Sequence; D015152:Blotting, Northern; D018076:DNA, Complementary / Q000302:isolation & purification; D005638:Fruit / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant; D018551:Solanum lycopersicum / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D008969:Molecular Sequence Data; D009154:Mutation; D010802:Phylogeny; D018749:RNA, Plant / Q000032:analysis; D017386:Sequence Homology, Amino Acid; D001616:beta-Galactosidase / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D018749:RNA, Plant; D001616:beta-Galactosidase