Post-transcriptional adenylation of signal recognition particle RNA is carried out by an enzyme different from mRNA Poly(A) polymerase.
A fraction of the signal recognition particle (SRP) RNA from human, rat, Xenopus, and Saccharomyces cerevisiae cells contains a single post-transcriptionally added adenylic acid residue on its 3'-end; in the case of human SRP RNA, over 60% of the SRP RNA molecules contain a nontemplated adenylic acid residue on their 3'-ends (Sinha, K. M., Gu, J., Chen, Y., and Reddy, R. (1998) J. Biol. Chem. 273, 6853-6859). In this study, we investigated the enzyme that is involved in this 3'-end adenylation of SRP RNA. A U1A protein peptide conjugated to albumin completely inhibited the polyadenylation of a SV40 mRNA by HeLa cell nuclear extract in vitro; however, the 3'-end adenylation of human SRP RNA or Alu RNA, which corresponds to 5' and 3'-ends of SRP RNA, was not affected by this U1A peptide conjugate. SRP RNA from mutant strains of S. cerevisiae with a temperature-sensitive mRNA poly(A) polymerase grown at a restrictive temperature of 37 degrees C also contained a post-transcriptionally added adenylic acid residue just like SRP RNA from wild-type cells and mutant cells grown at permissive temperature of 23 degrees C. In addition, binding of SRP 9/14-kDa protein heterodimer was required for adenylation of Alu RNA in vitro. These lines of evidence, along with other data, show that post-transcriptional adenylation of SRP and Alu RNAs is carried out by a novel enzyme that is distinct from the mRNA poly(A) polymerase, CCA-adding enzyme, and nonspecific terminal transferase.
Sinha
K
K
Department of Pharmacology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA.
Perumal
K
K
Chen
Y
Y
Reddy
R
R
D020087:Alu Elements / Q000235:genetics; D000818:Animals; D002467:Cell Nucleus / Q000201:enzymology*; D003574:Cytochrome c Group / Q000235:genetics; D045304:Cytochromes c; D019281:Dimerization; D006367:HeLa Cells; D006801:Humans; D007527:Isoenzymes / Q000235:genetics; D011061:Poly A / Q000378:metabolism; D011062:Polynucleotide Adenylyltransferase / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012367:RNA, Viral / Q000235:genetics / Q000378:metabolism; D051381:Rats; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle / Q000235:genetics*; D013539:Simian virus 40 / Q000235:genetics; D013696:Temperature; D014981:Xenopus
C014059:CYC1 protein, S cerevisiae; D003574:Cytochrome c Group; D007527:Isoenzymes; D012333:RNA, Messenger; D012367:RNA, Viral; D029701:Saccharomyces cerevisiae Proteins; D018271:Signal Recognition Particle; D011061:Poly A; D045304:Cytochromes c; D011062:Polynucleotide Adenylyltransferase