Abstract
In eukaryotes, almost all RNA species are processed at their 3′ ends and most mRNAs are polyadenylated in the nucleus by canonical poly(A) polymerases. In recent years, several terminal nucleotidyl transferases (TENTs) including non-canonical poly(A) polymerases (ncPAPs) and terminal uridyl transferases (TUTases) have been discovered. In contrast to canonical polymerases, TENTs' functions are more diverse; some, especially TUTases, induce RNA decay while others, such as cytoplasmic ncPAPs, activate translationally dormant deadenylated mRNAs. The mammalian genome encodes 11 different TENTs. This review summarizes the current knowledge about the functions and mechanisms of action of these enzymes.This article is part of the theme issue ‘5′ and 3′ modifications controlling RNA degradation’.
Highlights
Eukaryotic gene expression pathways are very complex and regulated at multiple levels
Based on their substrate preference towards adenosine monophosphate (AMP) or uridine monophosphate (UMP) incorporation, human TErminal NucleotidylTransferases (TENTs) are divided into non-canonical poly(A) polymerases and terminal uridyl transferases (TUTases), while phylogenetic analysis groups them into seven families [4,5]
All TENT5 homologues are highly similar in their amino acid sequences and share a common two-domain architecture with (i) an NTase domain distantly related to known NTase domains of other PAPs and TUTases, but comprising well conserved acidic amino acids in its putative catalytic centre and (ii) a poly(A) polymerase/20 –50-oligoadenylate synthetase 1 substrate binding domain (PAP/OAS1 SBD) [5,81]
Summary
Eukaryotic gene expression pathways are very complex and regulated at multiple levels. The maturation of oocytes is normal and the length of poly(A) tails of the reporter mRNA is altered neither in germline nor in somatic cells [33] This raises a possibility that in mammalian early embryos other yet unidentified TENT protein(s) might be involved in poly(A) length regulation [34] or that other processes like regulation of mRNA decay by uridylation-mediated mechanisms (see §3b on TUTases) play decisive roles [35]. All TENT5 homologues are highly similar in their amino acid sequences and share a common two-domain architecture with (i) an NTase domain distantly related to known NTase domains of other PAPs and TUTases, but comprising well conserved acidic amino acids in its putative catalytic centre and (ii) a poly(A) polymerase/20 –50-oligoadenylate synthetase 1 substrate binding domain (PAP/OAS1 SBD) [5,81] The latter 5 is likely involved in substrate RNA binding and stabilization during poly(A) tail formation.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
