title: The rnb gene of Synechocystis PCC6803 encodes a RNA hydrolase displaying RNase II and not RNase R enzymatic properties.
abstract: Cyanobacteria are photosynthetic prokaryotic organisms that share characteristics with bacteria and chloroplasts regarding mRNA degradation. Synechocystis sp. PCC6803 is a model organism for cyanobacteria, but not much is known about the mechanism of RNA degradation. Only one member of the RNase II-family is present in the genome of Synechocystis sp PCC6803. This protein was shown to be essential for its viability, which indicates that it may have a crucial role in the metabolism of Synechocystis RNA. The aim of this work was to characterize the activity of the RNase II/R homologue present in Synechocystis sp. PCC6803. The results showed that as expected, it displayed hydrolytic activity and released nucleoside monophosphates. When compared to two E. coli counterparts, the activity assays showed that the Synechocystis protein displays RNase II, and not RNase R characteristics. This is the first reported case where when only one member of the RNase II/R family exists it displays RNase II and not RNase R characteristics.
authors.affiliation: Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa, Oeiras, Portugal.
authors.forename: Rute G
authors.initials: RG
authors.lastname: Matos
authors.forename: Arsénio M
authors.initials: AM
authors.lastname: Fialho
authors.forename: Mordechai
authors.initials: M
authors.lastname: Giloh
authors.forename: Gadi
authors.initials: G
authors.lastname: Schuster
authors.forename: Cecília M
authors.initials: CM
authors.lastname: Arraiano
mesh_terms: D005095:Exoribonucleases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D008274:Magnesium / Q000378:metabolism; D008958:Models, Molecular; D010446:Peptide Fragments / Q000378:metabolism; D011487:Protein Conformation; D059748:Proteolysis; D012329:RNA, Bacterial / Q000378:metabolism*; D012492:Salts / Q000494:pharmacology; D013379:Substrate Specificity; D046939:Synechocystis / Q000201:enzymology* / Q000235:genetics*
chemical_list: D010446:Peptide Fragments; D012329:RNA, Bacterial; D012492:Salts; D005095:Exoribonucleases; C022535:exoribonuclease II; D008274:Magnesium