A genomic clone containing the promoter for the gene encoding the human lysosomal enzyme, alpha-galactosidase A

We have isolated and characterized a human genomic clone for a lysosomal enzyme gene. The start point of transcription was identified using primer extension of poly(A)+ mRNA. This genomic clone is specific for human alpha-galactosidase A, and it includes sequences for the promoter, complete signal peptide, first exon, and part of the first intron. Direct and inverted repeat elements of 10, 11, 16, 19, and 22 nucleotides (nt) flank the promoter site. A (GA)n repeat element of approx. 60 nt with strong homology to similar elements identified in several species is located upstream from the promoter. A GGGCGG site specific for DNA-binding protein Sp1 is located near a CAAT box, and the CCGCCC inverted repeat of the Sp1 binding sequence is located by the TATA box. The sequence immediately flanking the ATG start codon of the human alpha-galactosidase A is highly homologous to sequences flanking the ATG start codons of the other human lysosomal hydrolases for which sequence information is available (beta-glucocerebrosidase, cathepsin B, cathepsin D, and beta-hexosaminidase alpha chain), but not for any of the other 133 human signal peptides examined. Our analysis also reveals that conversion of the propeptide to the mature enzyme involves cleavage of a C-terminal rather than an N-terminal fragment. This information about the normal alpha-galactosidase A gene will be useful for comparison to data obtained from patients with Fabry disease, who are characterized by a deficiency of this enzyme. This is the first genomic clone described to date for any lysosomal enzyme, and it establishes a reference for future analyses of the molecular events that mediate the expression of this important class of enzymes.