MOLECULAR-CLONING AND CHARACTERIZATION OF BOVINE BETA-MANNOSIDASE

Deficiency of lysosomal beta-mannosidase activity results in a severe neurodegenerative disease in goats and cattle and a relatively milder phenotype in humans. A cDNA coding for the entire beta-mannosidase pro tein is described, Mixed oligonucleotides derived from bovine beta-man nosidase peptide sequences were used to screen a bovine thyroid cDNA l ibrary, Clones covering about 80% of the C-terminal region were recove red, The missing 5'-region was obtained using the technique of 5'-rapi d amplification of cDNA ends. The composite cDNA contains 3852 nucleot ides, encoding 879 amino acids. The N-terminal methionine is followed by 16 amino acids displaying the characteristics of a typical signal p eptide sequence. The deduced amino acid sequence is colinear with all peptide sequences determined by protein microsequencing, Northern blot analysis demonstrates a single 4.2-kilobase transcript in various tis sues from both normal and affected goats and calves, The mRNA level is decreased in tissues of affected beta-mannosidosis animals, The gene encoding beta-mannosidase is localized to human chromosome 4 as shown by Southern analysis of rodent/human somatic cell hybrids, This is the first report of cloning of lysosomal beta-mannosidase.