Polyadenylylation helps regulate mRNA decay in Escherichia coli.
As part of our genetic analysis of mRNA decay in Escherichia coli K-12, we examined the effect of the pcnB gene [encoding poly(A) polymerase I] on message stability. Eliminating poly(A) polymerase I (delta pcnB) dramatically stabilized the lpp, ompA, and trxA transcripts. The half-lives of individual mRNAs were increased in both a delta pcnB single mutant and a delta pcnB pnp-7 rnb-500 rne-1 multiple mutant. We also found mRNA decay intermediates in delta pcnB mutants that were not detected in control strains. By end-labeling total E. coli RNA with [32P]pCp and T4 RNA ligase and then digesting the RNA with RNase A and T1, we showed that many RNAs in a wild-type strain contained poly(A) tails ranging from 10 nt to > 50 nt long. When polynucleotide phosphorylase, RNase II, and RNase E were absent, the length (> 100 nt) and number (10- to 20-fold) of the poly(A) tails increased. After transcription initiation was stopped with rifampicin, polyadenylylation apparently continued. Deleting the structural gene for poly(A) polymerase I (pcnB) reduced the amount of 3'-terminal poly(A) sequences by > 90%. We propose a model for the role of polyadenylylation in mRNA decay.
O'Hara
E B
EB
Department of Genetics, University of Georgia, Athens 30602-7223.
Chekanova
J A
JA
Ingle
C A
CA
Kushner
Z R
ZR
Peters
E
E
Kushner
S R
SR
D015152:Blotting, Northern; D004926:Escherichia coli / Q000378:metabolism*; D015870:Gene Expression; D005798:Genes, Bacterial; D006207:Half-Life; D006706:Homeostasis; D016296:Mutagenesis; D011061:Poly A / Q000032:analysis; D011062:Polynucleotide Adenylyltransferase / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism; D012329:RNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*
D012329:RNA, Bacterial; D012333:RNA, Messenger; D011061:Poly A; D011062:Polynucleotide Adenylyltransferase