Biomaterial Database

The CCA-adding enzyme: A central scrutinizer in tRNA quality control. 2015

Heike Betat, and Mario Mörl

Institute for Biochemistry, University of Leipzig, Leipzig, Germany.

tRNA nucleotidyltransferase adds the invariant CCA-terminus to the tRNA 3'-end, a central step in tRNA maturation. This CCA-adding enzyme is a specialized RNA polymerase that synthesizes the CCA sequence at high fidelity in all kingdoms of life. Recently, an additional function of this enzyme was identified, where it generates a specific degradation tag on structurally unstable tRNAs. This tag consists of an additional repeat of the CCA triplet, leading to a 3'-terminal CCACCA sequence. In order to explain how the enzyme catalyzes this extended polymerization reaction, Kuhn et al. solved a series of co-crystal structures of the CCA-adding enzyme from Archaeoglobus fulgidus in complex with different tRNA substrates. They show that the enzyme forces a bound unstable tRNA to refold the acceptor stem for a second round of CCA-addition, while stable transcripts are robust enough to resist this isomerization. In this review, we discuss how the CCA-adding enzyme uses a simple yet very elegant way to scrutinize its substrates for sufficient structural stability and, consequently, functionality.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009690	Nucleic Acid Conformation	The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.	DNA Conformation,RNA Conformation,Conformation, DNA,Conformation, Nucleic Acid,Conformation, RNA,Conformations, DNA,Conformations, Nucleic Acid,Conformations, RNA,DNA Conformations,Nucleic Acid Conformations,RNA Conformations
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001483	Base Sequence	The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.	DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA
D012316	RNA Nucleotidyltransferases	Enzymes that catalyze the template-directed incorporation of ribonucleotides into an RNA chain. EC 2.7.7.-.	Nucleotidyltransferases, RNA
D012343	RNA, Transfer	The small RNA molecules, 73-80 nucleotides long, that function during translation (TRANSLATION, GENETIC) to align AMINO ACIDS at the RIBOSOMES in a sequence determined by the mRNA (RNA, MESSENGER). There are about 30 different transfer RNAs. Each recognizes a specific CODON set on the mRNA through its own ANTICODON and as aminoacyl tRNAs (RNA, TRANSFER, AMINO ACYL), each carries a specific amino acid to the ribosome to add to the elongating peptide chains.	Suppressor Transfer RNA,Transfer RNA,tRNA,RNA, Transfer, Suppressor,Transfer RNA, Suppressor,RNA, Suppressor Transfer
D020871	RNA Stability	The extent to which an RNA molecule retains its structural integrity and resists degradation by RNASE, and base-catalyzed HYDROLYSIS, under changing in vivo or in vitro conditions.	RNA Decay,mRNA Decay,mRNA Transcript Degradation,RNA Degradation,RNA Instability,mRNA Degradation,mRNA Instability,mRNA Stability,Decay, RNA,Decay, mRNA,Degradation, RNA,Degradation, mRNA,Degradation, mRNA Transcript,Instability, RNA,Instability, mRNA,Stability, RNA,Stability, mRNA,Transcript Degradation, mRNA