The Structures, Functions, and Evolution of Sm-like Archaeal Proteins (SmAPs)

TL;DR

This paper reports the crystal structures of archaeal homologs of Sm proteins, providing insights into their roles in RNA processing and the assembly of ribonucleoprotein complexes, advancing understanding of snRNP core structures.

Contribution

It presents the first high-resolution structures of archaeal Sm-like proteins, shedding light on their function and evolution in RNA processing complexes.

Findings

Crystal structures of archaeal Sm-like proteins determined

Insights into the assembly of ribonucleoprotein complexes

Enhanced understanding of Sm protein evolution

Abstract

Sm proteins were discovered nearly 20 years ago as a group of small antigenic proteins ($\approx$ 90-120 residues). Since then, an extensive amount of biochemical and genetic data have illuminated the crucial roles of these proteins in forming ribonucleoprotein (RNP) complexes that are used in RNA processing, e.g., spliceosomal removal of introns from pre-mRNAs. Spliceosomes are large macromolecular machines that are comparable to ribosomes in size and complexity, and are composed of uridine-rich small nuclear RNPs (U snRNPs). Various sets of seven different Sm proteins form the cores of most snRNPs. Despite their importance, very little is known about the atomic-resolution structure of snRNPs or their Sm cores. As a first step towards a high-resolution image of snRNPs and their hierarchic assembly, we have determined the crystal structures of archaeal homologs of Sm proteins, which we term Sm-like archaeal proteins (SmAPs).