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 hydrolysis of N alpha-acylated amino acids. ACY1 has been assigned to chromosome 3p21.1, a region reduced to homozygosity in small cell lung cancer (SCLC), and has been reported to exhibit reduced or absent expression in SCLC cell lines and tumors. Two human cDNA libraries and one human genomic DNA library were screened with a previously isolated partial ACY1 cDNA to isolate a full-length transcript. Sequence analysis of clones from each of these libraries resulted in an ACY1 cDNA of 1438 base pairs with an open reading frame of 1224-base pairs coding for a putative protein of 408 amino acids with a predicted molecular mass of 45,882 Da. Sequence analysis revealed no homologies to previously reported cDNA or protein sequences and establishes ACY1 as the first member of a new family of zinc-binding enzymes to be so characterized. The subcellular location of ACY1 has been established as cytosolic by flow cytometry. Southern and northern analyses of ACY1 in SCLC cell lines failed to demonstrate any gross abnormalities of the ACY1 structural gene or instances of absent or aberrantly sized mRNA, respectively.