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Proc Natl Acad Sci U S A. 2016 Feb 2;113(5):1279-84. doi: 10.1073/pnas.1524400113. Epub 2016 Jan 19.

PGL germ granule assembly protein is a base-specific, single-stranded RNase.

Author information

1
Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706;
2
Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53706.
3
Department of Biochemistry, University of Wisconsin-Madison, Madison, WI 53706; Howard Hughes Medical Institute, University of Wisconsin-Madison, Madison, WI 53706 jekimble@wisc.edu.

Abstract

Cellular RNA-protein (RNP) granules are ubiquitous and have fundamental roles in biology and RNA metabolism, but the molecular basis of their structure, assembly, and function is poorly understood. Using nematode "P-granules" as a paradigm, we focus on the PGL granule scaffold protein to gain molecular insights into RNP granule structure and assembly. We first identify a PGL dimerization domain (DD) and determine its crystal structure. PGL-1 DD has a novel 13 α-helix fold that creates a positively charged channel as a homodimer. We investigate its capacity to bind RNA and discover unexpectedly that PGL-1 DD is a guanosine-specific, single-stranded endonuclease. Discovery of the PGL homodimer, together with previous results, suggests a model in which the PGL DD dimer forms a fundamental building block for P-granule assembly. Discovery of the PGL RNase activity expands the role of RNP granule assembly proteins to include enzymatic activity in addition to their job as structural scaffolds.

KEYWORDS:

P-granules; PGL-1; PGL-3; RNA endonuclease; germ-cell development

PMID:
26787882
PMCID:
PMC4747772
DOI:
10.1073/pnas.1524400113
[Indexed for MEDLINE]
Free PMC Article

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