Molecular Characterization of Three PRORP Proteins in the Moss Physcomitrella patens: Nuclear PRORP Protein Is Not Essential for Moss ViabilityReport as inadecuate




Molecular Characterization of Three PRORP Proteins in the Moss Physcomitrella patens: Nuclear PRORP Protein Is Not Essential for Moss Viability - Download this document for free, or read online. Document in PDF available to download.

RNase P is a ubiquitous endonuclease that removes the 5′ leader sequence from pre-tRNAs in all organisms. In Arabidopsis thaliana, RNA-free proteinaceous RNase Ps PRORPs seem to be enzymes for pre-tRNA 5′-end processing in organelles and the nucleus and are thought to have replaced the ribonucleoprotein RNase P variant. However, the evolution and function of plant PRORPs are not fully understood. Here, we identified and characterized three PRORP-like proteins, PpPPR 63, 67, and 104, in the basal land plant, the moss Physcomitrella patens. PpPPR 63 localizes to the nucleus, while PpPPR 67 and PpPPR 104 are found in both the mitochondria and chloroplasts. The three proteins displayed pre-tRNA 5′-end processing activity in vitro. Mutants with knockout KO of the PpPPR 63 gene displayed growth retardation of protonemal colonies, indicating that, unlike Arabidopsis nuclear RPORPs, the moss nuclear PpPPR 63 is not essential for viability. In the KO mutant, nuclear-encoded tRNAAsp GUC levels were slightly decreased, whereas most nuclear-encoded tRNA levels were not altered. This indicated that most of the cytosolic mature tRNAs were produced normally without proteinaceous RNase P-like PpPPR 63. Single PpPPR 67 or 104 gene KO mutants displayed different phenotypes of protonemal growth and chloroplast tRNAArg ACG accumulation. However, the levels of all other tRNAs were not altered in the KO mutants. In addition, in vitro RNase P assays showed that PpPPR 67 and PpPPR 104 efficiently cleaved chloroplast pre-tRNAArg CCG and pre-tRNAArg UCU but they cleaved pre-tRNAArg ACG with different efficiency. This suggests that the two proteins have overlapping function but their substrate specificity is not identical.



Author: Chieko Sugita , Yoshihiro Komura , Korechika Tanaka, Kazuki Kometani, Hiroyuki Satoh, Mamoru Sugita

Source: http://plos.srce.hr/



DOWNLOAD PDF




Related documents