Chloroplast mRNA 3'-end processing by a high molecular weight protein complex is regulated by nuclear encoded RNA binding proteins.
In the absence of efficient transcription termination correct 3'-end processing is an essential step in the synthesis of stable chloroplast mRNAs in higher plants. We show here that 3'-end processing in vitro involves endonucleolytic cleavage downstream from the mature terminus, followed by exonucleolytic processing to a stem-loop within the 3'-untranslated region. These processing steps require a high molecular weight complex that contains both endoribonucleases and an exoribonuclease. In the presence of ancillary RNA binding proteins the complex correctly processes the 3'-end of precursor RNA. In the absence of these ancillary proteins 3'-end maturation is prevented and plastid mRNAs are degraded. Based on these results we propose a novel mechanism for the regulation of mRNA 3'-end processing and stability in chloroplasts.
Hayes
R
R
Waksman Institute, Rutgers University, Piscataway, NJ 08855-0759, USA.
Kudla
J
J
Schuster
G
G
Gabay
L
L
Maliga
P
P
Gruissem
W
W
D000595:Amino Acid Sequence; D002736:Chloroplasts / Q000378:metabolism*; D003573:Cytochrome b Group / Q000235:genetics; D045346:Cytochrome b6f Complex; D004722:Endoribonucleases / Q000378:metabolism; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010940:Plant Proteins / Q000378:metabolism*; D018087:Plastids / Q000378:metabolism; D011117:Polyribonucleotide Nucleotidyltransferase / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012333:RNA, Messenger / Q000378:metabolism*; D018749:RNA, Plant / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D018724:Spinacia oleracea / Q000235:genetics / Q000378:metabolism
D003573:Cytochrome b Group; D010940:Plant Proteins; D012333:RNA, Messenger; D018749:RNA, Plant; D016601:RNA-Binding Proteins; D012261:Ribonucleoproteins; C084072:petD protein, cytochrome b(6)f complex; D045346:Cytochrome b6f Complex; D011117:Polyribonucleotide Nucleotidyltransferase; D004722:Endoribonucleases