title: A chloroplast transcript lacking the 3' inverted repeat is degraded by 3'-->5' exoribonuclease activity.
abstract: Chlamydomonas reinhardtii strains harboring deletions of the chloroplast atpB 3' inverted repeat (IR) are weakly phototrophic due to reduced accumulation of discrete atpB transcripts and the chloroplast ATPase beta-subunit protein. A sequence of 18 guanosine residues, which can impede a 3'-->5' exoribonuclease in vitro, is able to substitute for the atpB IR in vivo. Strains containing the poly-guanosine tract in place of the atpB 3' IR are phototrophic and accumulate near wild-type levels of discrete atpB transcripts and the ATPase beta-subunit protein. Because these atpB transcripts contain the 18 guanosine residues, and the poly-guanosine tract is not a terminator of transcription, the accumulation of discrete atpB transcripts is likely the result of impediment of 3'-->5' exoribonuclease activity. These findings support a model in which atpB transcripts lacking the 3' IR are degraded by 3'-->5' exoribonuclease activity, and demonstrate that the poly-guanosine tract can be used to study chloroplast RNA metabolism in vivo.
authors: Boyce Thompson Institute for Plant Research, Cornell University, Ithaca, New York 14853, USA.
authors: R G
authors: RG
authors: Drager
authors: M
authors: M
authors: Zeidler
authors: C L
authors: CL
authors: Simpson
authors: D B
authors: DB
authors: Stern
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism; D000818:Animals; D001483:Base Sequence; D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000254:growth & development / Q000502:physiology; D002736:Chloroplasts / Q000235:genetics* / Q000502:physiology; D004926:Escherichia coli / Q000201:enzymology; D005095:Exoribonucleases / Q000235:genetics* / Q000378:metabolism*; D006151:Guanosine / Q000737:chemistry; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010788:Photosynthesis / Q000235:genetics; D010957:Plasmids / Q000235:genetics; D011089:Polydeoxyribonucleotides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014170:Transformation, Genetic
chemical_list: D011089:Polydeoxyribonucleotides; D006151:Guanosine; D005095:Exoribonucleases; D000251:Adenosine Triphosphatases