@article {Germain:2011:0960-7412:381,
title = "Mutational analysis of Arabidopsis chloroplast polynucleotide phosphorylase reveals roles for both RNase PH core domains in polyadenylation, RNA 3end maturation and intron degradation",
journal = "The Plant Journal",
parent_itemid = "infobike://bsc/tpj",
publishercode ="bp",
year = "2011",
volume = "67",
number = "3",
publication date ="2011-08-01T00:00:00",
pages = "381-394",
itemtype = "ARTICLE",
issn = "0960-7412",
eissn = "1365-313X",
url = "https://www.ingentaconnect.com/content/bsc/tpj/2011/00000067/00000003/art00001",
doi = "doi:10.1111/j.1365-313X.2011.04601.x",
author = "Germain, Arnaud and Herlich, Shira and Larom, Shirley and Kim, Sang Hu and Schuster, Gadi and Stern, David B.",
abstract = "Summary Polynucleotide phosphorylase (PNPase) catalyzes RNA polymerization and 35 phosphorolysis in vitro, but its roles in plant organelles are poorly understood. Here, we have used in vivo and in vitro
mutagenesis to study Arabidopsis chloroplast PNPase (cpPNPase). In mutants lacking cpPNPase activity, unusual RNA patterns were broadly observed, implicating cpPNPase in rRNA and mRNA 3end maturation, and RNA degradation. Introncontaining fragments also accumulated in
mutants, and cpPNPase appears to be required for a degradation step following endonucleolytic cleavage of the excised lariat. Analysis of poly(A) tails, which destabilize chloroplast RNAs, indicated that PNPase and a poly(A) polymerase share the polymerization role in wildtype plants.
We also studied two lines carrying mutations in the first PNPase core domain, which does not harbor the catalytic site. These mutants had genedependent and intermediate RNA phenotypes, suggesting that reduced enzyme activity differentially affects chloroplast transcripts. The interpretations
of in vivo results were confirmed by in vitro analysis of recombinant enzymes, and showed that the first core domain affects overall catalytic activity. In summary, cpPNPase has a major role in maturing mRNA and rRNA 3ends, but also participates in RNA degradation
through exonucleolytic digestion and polyadenylation. These functions depend absolutely on the catalytic site within the second duplicated RNase PH domain, and appear to be modulated by the first RNase PH domain.",
}