Extreme heterogeneity of polyadenylation sites in mRNAs encoding chloroplast RNA-binding proteins in Nicotiana plumbaginifolia.
We have previously characterized nuclear cDNA clones encoding two RNA binding proteins, CP-RBP30 and CP-RBP-31, which are targeted to chloroplasts in Nicotiana plumbaginifolia. In this report we describe the analysis of the 3'-untranslated regions (3'-UTRs) in 22 CP-RBP30 and 8 CP-RBP31 clones which reveals that mRNAs encoding both proteins have a very complex polyadenylation pattern. Fourteen distinct poly(A) sites were identified among CP-RBP30 clones and four sites among the CP-RBP31 clones. The authenticity of the sites was confirmed by RNase A/T1 mapping of N. plumbaginifolia RNA. CP-RBP30 provides an extreme example of the heterogeneity known to be a feature of mRNA polyadenylation in higher plants. Using PCR we have demonstrated that CP-RBP genes in N. plumbaginifolia and N. sylvestris, in addition to the previously described introns interrupting the coding region, contain an intron located in the 3' non-coding part of the gene. In the case of the CP-RBP31, we have identified one polyadenylation event occurring in this intron.
Klahre
U
U
Friedrich Miescher-Institut, Basel, Switzerland.
Hemmings-Mieszczak
M
M
Filipowicz
W
W
D001483:Base Sequence; D002736:Chloroplasts / Q000378:metabolism*; D018076:DNA, Complementary; D006868:Hydrolysis; D008969:Molecular Sequence Data; D010947:Plants, Toxic; D011061:Poly A / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D018749:RNA, Plant / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
D018076:DNA, Complementary; D012333:RNA, Messenger; D018749:RNA, Plant; D016601:RNA-Binding Proteins; D011061:Poly A