Kiss your tail goodbye: the role of PARN, Nocturnin, and Angel deadenylases in mRNA biology

Abstract

PARN, Nocturnin and Angel are three of the multiple deadenylases that have been described in eukaryotic cells. While each of these enzymes appear to target poly(A) tails for shortening and influence RNA gene expression levels and quality control, the enzymes differ in terms of enzymatic mechanisms, regulation and biological impact. The goal of this review is to provide an in depth biochemical and biological perspective of the PARN, Nocturnin and Angel deadenylases. Understanding the shared and unique roles of these enzymes in cell biology will provide important insights into numerous aspects of the post-transcriptional control of gene expression. This article is part of a Special Issue entitled: RNA Decay mechanisms.

Figure 1. Boxshade2 analysis of ClustalW alignment of PARN from various species

Black shading exactly conserved amino acids; Gray shading conservative substitutions of amino acids. Genbank accession numbers are as cited. Mm: Mus musculus NP_083037; Hs: Homo sapiens AAH50029; Gg: Gallus gallus NP_001025800; Xl: Xenopus laevis NP_001081143; Dr: Danio rerio NP_957382; At: Arabidopsis thaliana Genbank 60390594; Ce: Caenorhabditis elegans from [7]; Ano Anopheles gambiae from [4]; Aed Aedes aegypti from [4] ; Tb1 Trypanosome brucei Genbank AAZ13051.

Figure 2. Schematic representation of the mouse Ccr4 homologs

Each has a conserved nuclease domain (shown in gray) related to a class of Mg2+-dependent Exonucleases-Endonucleases-Phosphatases, known as the EEP superfamily. Cnot6 and Cnot6l possess N-terminal Leucine Rich Repeats (LRRs) (shown in black), which are conserved in yeast Ccr4p. GenBank accession numbers are as given: Ccrn4l (Nocturnin/Ccr4c), NP_033964; Angel1 (Ccr4e), NP_653107; Angel2 (Ccr4d), NP_067396; Cnot6 (Ccr4a), NP_997649; Cnot6l(Ccr4b), NP_659159.