Characterization of squid crystallin genes. Comparison with mammalian glutathione S-transferase genes

• Published in: The Journal of biological chemistry Vol. 267; no. 12; pp. 8604 - 8612
• Main Authors: TOMAREV, S. I, ZINOVIERA, R. D, PIATIGORSKY, J
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Society for Biochemistry and Molecular Biology 25.04.1992
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Biological and medical sciences; Blotting, Northern; Blotting, Southern; cDNA; Cell Line; Chloramphenicol O-Acetyltransferase - genetics; Chloramphenicol O-Acetyltransferase - metabolism; comparative studies; Crystallins - genetics; Decapodiformes; DNA - genetics; eye lens; Fundamental and applied biological sciences. Psychology; genes; Genes. Genome; glutathione transferase; Glutathione Transferase - genetics; homology; Kidney - cytology; Kidney - enzymology; Marine; marine molluscs; Molecular and cellular biology; Molecular genetics; Molecular Sequence Data; nucleotide sequence; Ommastrephes sloani pacificus; peptides; predictions; Rabbits; RNA - genetics; S-crystallin; Sequence Homology, Nucleic Acid; TATA Box; Transcription, Genetic; Nucleotide sequence; Enzyme; Gene organization; Proteins; Cephalopoda; Vertebrata; Crystallin; Mammalia; Enzymatic activity; Gene; Glutathione transferase; Invertebrata; Mollusca; Comparative study; Aminoacid sequence
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)42486-6

Previous experiments have indicated that the crystallins of the squid lens (S-crystallins) are evolutionarily related to glutathione S-transferases (GST) (EC 2.5.1.18). Here we confirm by peptide sequencing that the crystallins of the lens of the squid Ommastrephes sloani pacificus comprise a family of GST-like proteins. Squid lens extracts showed 400 times less GST activity than those of liver using 1-chloro-2,4-dinitrobenzene as a substrate, suggesting that the abundant GST-like crystallins lack enzymatic activity. Four different cDNAs (pSL20-1, pSL18, pSL11, and pSL4) showed 20-25% similarity in homologous regions with mammalian GST polypeptides. pSL20-1, pSL18, and pSL4 each encode an S-crystallin with a unique internal peptide that is unrelated to mammalian GSTs or any other sequence in GenBank. The S-crystallin family is encoded in a minimum of 9-10 genes, and the exon-intron structures of at least two of these (SL20-1 and SL11) are similar to those of the mammalian GST genes. The SL20-1 gene has six exons, with the its unique internal peptide encoded precisely in exon 4; the SL11 gene lacks a unique internal peptide and has five exons. Experiments using bacterial chloramphenicol acetyltransferase as a reporter gene showed that at least 84 and 111 base pairs of 5'-flanking sequence are needed for function of the SL20-1 and SL11 promoters, respectively, in a transfected rabbit lens epithelial cell line (N/N1003A). Within these regions each has a putative TATA box and an upstream AP-1 site overlapping with antioxidant responsive-like elements, which are regulatory elements in the rat GST Ya and quinone reductase genes responsive to oxidative stress.