SpliceosomeStructure · Structural role of protein splicing factors in promoting an active configuration of the spliceosome's RNA catalytic core

Structural role of protein splicing factors in promoting an active configuration of the spliceosome's RNA catalytic core

To synthesize the building blocks of living organisms – proteins – cells use the information contained in their genetic material (DNA) as a blueprint. During gene expression cells make copies of their DNA in the form of pre-messenger RNAs (pre-mRNA). When first synthesized, the information coding for proteins is interrupted in pre-mRNAs by non-coding sequences, called introns. Accurate expression of the genetic material, and thus accurate protein synthesis, relies on the correct removal of introns from pre-mRNAs to produce mature messenger RNAs (mRNAs). Intron removal is called splicing and is performed by the spliceosome, a very dynamic cellular machine composed of both proteins and RNA. Errors in splicing result in distorted mRNAs and can lead to abnormal proteins that interfere with the normal functions of cells and often cause disease. Over the past 40 years much research was being carried out to understand how the spliceosome recognizes correct splicing sequences in pre-mRNAs and how specific mutations of such sequences can lead to aberrant splicing. However, such detailed understanding of splicing had been severely impaired by the lack of a proper understanding of the three-dimensional arrangement at the atomic level of specific RNA and protein components of the spliceosome. The goal of this work was to utilize recent advances in the three-dimensional study of macromolecules in combination with novel methods to purify spliceosomes from cells in order to obtain such a detailed picture of the spatial arrangement of the spliceosome with high resolution. Specifically, the work aimed to understand how each component of the spliceosome interacts with other components to form this complex cellular machine and promote its catalytic activity. Through this work we have elucidated the high-resolution structure of the spliceosome in several states and have shed light not only on the arrangement of its protein and RNA components at the molecular level but also on the dynamic rearrangements of these components during the splicing cycle. The structures of the catalytic spliceosome resulting from this work have further revealed the physical basis for how the spliceosome assembles properly at the correct pre-mRNA sequences and promotes proper splicing, thus rationalizing decades of previous biochemical and genetic research.

Data: CORDIS, © European Union