Domain Analysis of the Chloroplast Polynucleotide Phosphorylase Reveals Discrete Functions in RNA Degradation, Polyadenylation, and Sequence Homology with Exosome Proteins. The Plant Cell , Vol. 15, 2003-2019, September 2003
Domain Analysis of the Chloroplast Polynucleotide Phosphorylase Reveals Discrete Functions in RNA Degradation, Polyadenylation, and Sequence Homology with Exosome Proteins
The Plant Cell, Vol. 15, 2003-2019, September 2003
Shlomit Yehudai-Resheffa, Victoria Portnoya, Sivan Yogeva, Noam Adirb and Gadi Schuster1
1.chloroplast mRNA degradation (chloroplast and bacteria)
1). endonucleolytic cleavage
2). addition of poly(A)-rich sequences to the endonucleolytic cleavage products
(PAP in E.coli)
3). exonucleolytic degradation
2.PNPase in the chloroplast was found to form a homotrimeric complex
and lacks any known interactions with other proteins.
RNA. 7, (2001), 1464–1475
3.No PAP can be detected in spinach chloroplasts, and thus both
polyadenylation and degradation are performed by one enzyme,
Mol. Cell. Biol.21, (2001), 5408–5416
core = RNase PH domain Phosphorylase Reveals Discrete Functions in RNA Degradation, Polyadenylation, and Sequence Homology with Exosome ProteinsThe spinach chloroplast PNPase structure is similar to that of the bacterial enzyme
The amino acid sequence and domain structure is largely conserved between bacteria and organelles.
# bacteria : domain 2 have activity only
Degradation : domain 1 and 2
Polymerization : domain 2
Product : NDP (TLC)
UV light cross-linking assay
(Lisitsky et al., 1997b; Lisitsky and Schuster, 1999).
UV light cross-linking competition assay
substrate : 32P-psbA RNA
domain 2 (only)
PNPase enzyme is its pausing at a stem-loop structure when processively degrading RNA.
EMBO J. (1996) 15, 1132–1141
E. coli PAP I is inhibited by a stem-loop structure but that the addition of two nucleotides 3' to the stem loop is sufficient to promote efficient polyadenylation.
Nucleic Acids Res.(2000) 28, 1139–1144.
E. coli strain SK 8992
E. ColiArcheal Yeast Human
PNPase Rrp41 Rrp41p/Ski6p hRrp41p RNase PH Q17533
(x 3) (x 3) Rrp46p hRrp46p RNase PH (Crn-5)
Mtr3p hMtr3p RNase PH
Rrp42 Rrp42phRrp42p RNase PH NP_508024
(x 3) Rrp43pOIP2 RNase PH
Rrp45p PM/Scl-75 RNase PH T28842
Csl4 Csl4p/Ski4p hCsl4p S1 RBD
Rrp4p Rrp4phRrp4p S1/KH
Rrp40p hRrp40p S1/KH
Other common proteins:
(RNase R?) Rrp44p/Dis3p (hDis3p) RNase R
(RNase D?) Rrp6p PM/Scl-100 RNase D (Crn-3)(nuclear only)
PNPase (x3 ?)
red: in vitro 3’-5’exonuclease activity
PNPase lacks any known interactions with other proteins.