Two zebrafish (Danio rerio) antizymes with different expression and activitiesThe nucleotide sequence data reported will appear in DDBJ, EMBL and GenBank Nucleotide Sequence Databases under the accession numbers AB017117 (AZS) and AB017118 (AZL).

Abstract

Cellular polyamines are regulated by a unique feedback mechanism involving ornithine decarboxylase (ODC) antizyme. The synthesis of mammalian antizyme requires a programmed translational frameshift event induced by polyamines. Antizyme represses ODC, a key enzyme for polyamine synthesis, through accelerating enzyme degradation by the 26 S proteasome. Antizyme also inhibits the cellular uptake of polyamines. In the present study we isolated two distinct zebrafish (Danio rerio) antizyme cDNA clones (AZS and AZL) from an embryonic library. Their sequences revealed that both clones required translational frameshifting for expression. Taking account of +1 frameshifting, AZS and AZL products were 214 and 218 residues long respectively and shared 51.8% amino acid identity. In rabbit reticulocyte lysates, both mRNA species were translated through spermidine-induced frameshifting. The presence of the two antizyme mRNA species in embryos, adult fish and a cultured cell line was confirmed by Northern blot analysis. The ratio of AZS mRNA to AZL mRNA in the adult fish was 1.8-fold higher than in the embryos. Whole-mount hybridization in situ demonstrated that both mRNA species are expressed in every tissue in embryo, but predominantly in the central nervous system and the eyes. Bacterial expression products of both cDNA species inhibited ODC activity, but only the AZS product accelerated ODC degradation in vitro. These results show that both zebrafish antizymes are induced by polyamines but their mRNA species are expressed differently during development. The difference in activities on ODC degradation suggests their functional divergence.

Ribosomal frameshifting in decoding antizyme mRNAs from yeast and protists to humans: close to 300 cases reveal remarkable diversity despite underlying conservation

“…Two paralogs of antizymes in zebrafish ( Danio rerio ), AZS and AZL, are also ubiquitously expressed although each shows a distinct expression profile in developing embryos (72). The antizyme homolog in Drosophila is also ubiquitously expressed (73), and probably in other animals also.…”

“…One is known as ‘1S’ and the other as ‘1L’ (though S and L originally referred to short and long, analysis of further sequences showed that the length difference between the paralogous pair in a particular species maybe as small as 1 amino acid, and also that the S ortholog in one species can be longer than the L form of another species). Orthologs of antizyme 1S have the same arrangement of AUGs in ORF1 as higher vertebrates while orthologs of antizyme 1L usually have three in-frame AUGs in their ORF1 (99,100). …”

RefSeq curation and annotation of antizyme and antizyme inhibitor genes in vertebrates

“…To date, we have reviewed each of the three antizyme genes in 91 vertebrate organisms. This review included two antizyme 1 paralogs ( oaz1a/azs and oaz1b/azl ) in fish ( 23 ) and the novel, retina-specific antizyme ( oaz2b/azr ) in zebrafish ( 24 ). The GeneID and RefSeq identifiers and other related information for the genes reviewed in different organisms are provided in Supplemental Table S1, and general statistics of the data reviewed are summarized in Table 2 .…”