Related Experiment Videos
Running rings around RNA: a superfamily of phosphate-dependent RNases
Martyn F Symmons1, Mark G Williams, Ben F Luisi
1Dept of Biochemistry, University of Cambridge, Cambridge, UK.
Abstract:
The exosome of Saccharomyces cerevisiae and the degradosome of Escherichia coli are multienzyme complexes involved in the degradation of mRNA. Both contain enzymes that are similar to the phosphate-dependent exoribonuclease RNase PH. These enzymes are phosphorylases that degrade RNA from the 3'-end. A recent X-ray crystallographic study of the polynucleotide phosphorylase (PNPase) from Streptomyces antibioticus reveals, for the first time, the atomic structure of a member of the RNase PH superfamily. Here, information from the structure of PNPase is used to address two related issues. First, the structure supports the idea that PNPase, which is a trimer of multidomain subunits, arose by duplication of a gene encoding an RNase PH-like enzyme. Second, the structure might explain how RNase PH-like enzymes associate into oligomeric rings that degrade RNA in a processive reaction.
Insights
The structure of polynucleotide phosphorylase (PNPase) reveals insights into RNA degradation. This study supports PNPase
Area of Science:
- Molecular Biology
- Structural Biology
- Biochemistry
Background:
- Exosomes and degradosomes are multienzyme complexes responsible for messenger RNA (mRNA) degradation.
- These complexes contain phosphate-dependent exoribonucleases, such as Ribonuclease PH (RNase PH), which degrade RNA from the 3'-end.
Purpose of the Study:
- To elucidate the atomic structure of polynucleotide phosphorylase (PNPase) from Streptomyces antibioticus, a member of the RNase PH superfamily.
- To use structural information to understand the evolutionary origins and oligomeric assembly of RNase PH-like enzymes.
Main Methods:
- X-ray crystallography was employed to determine the atomic structure of PNPase.
Main Results:
- The study provides the first atomic structure of an RNase PH superfamily member.
- The trimeric structure of PNPase, composed of multidomain subunits, suggests evolution through gene duplication of an RNase PH-like enzyme.
- The structure offers potential explanations for the formation of ring-like oligomers involved in processive RNA degradation.
Conclusions:
- The determined structure of PNPase provides crucial insights into the RNase PH superfamily.
- Structural data supports an evolutionary model of gene duplication for PNPase.
- The findings may explain the mechanism of processive RNA degradation by RNase PH-like enzyme oligomers.