PNPase activity determines the efficiency of mRNA 3'-end processing, the degradation of tRNA and the extent of polyadenylation in chloroplasts.

ABSTRACT: The exoribonuclease polynucleotide phosphorylase (PNPase) has been implicated in mRNA processing and degradation in bacteria as well as in chloroplasts of higher plants. Here, we report the first comprehensive in vivo study of chloroplast PNPase function. Modulation of PNPase activity in Arabidopsis chloroplasts by a reverse genetic approach revealed that, although this enzyme is essential for efficient 3'-end processing of mRNAs, it is insufficient to mediate transcript degradation. Surprisingly, we identified PNPase as also being indispensable for 3'-end maturation of 23S rRNA transcripts. Analysis of tRNA amounts in transgenic Arabidopsis plants suggests a direct correlation of PNPase activity and tRNA levels, indicating an additional function of this exoribo nuclease in tRNA decay. Mor

SUBMITTER: Walter M 

PROVIDER: S-EPMC139106 | biostudies-literature | 2002 Dec

REPOSITORIES: biostudies-literature