HUMAN AMINOACYLASE-1 - CLONING, SEQUENCE, AND EXPRESSION ANALYSIS OF A CHROMOSOME-3P21 GENE INACTIVATED IN SMALL-CELL LUNG-CANCER

Human aminoacylase-1 (N-acyl-L-amino-acid amidohydrolase, EC 3.5.1.14; ACY1) is a homodimeric zinc-binding enzyme that catalyzes the hydroly sis of N(alpha)-acylated amino acids. ACY1 has been assigned to chromo some 3p21.1, a region reduced to homozygosity in small cell lung cance r (SCLC), and has been reported to exhibit reduced or absent expressio n in SCLC cell lines and tumors. Two human cDNA libraries and one huma n genomic DNA library were screened with a previously isolated partial ACY1 cDNA to isolate a full-length transcript. Sequence analysis of c lones from each of these libraries resulted in an ACY1 cDNA of 1438 ba se pairs with an open reading frame of 1224-base pairs coding for a pu tative protein of 408 amino acids with a predicted molecular mass of 4 5,882 Da. Sequence analysis revealed no homologies to previously repor ted cDNA or protein sequences and establishes ACY1 as the first member of a new family of zinc-binding enzymes to be so characterized. The s ubcellular location of ACY1 has been established as cytosolic by flow cytometry. Southern and northern analyses of ACY1 in SCLC cell lines f ailed to demonstrate any gross abnormalities of the ACY1 structural ge ne or instances of absent or aberrantly sized mRNA, respectively.