Dynamics and consequences of spliceosome E complex formation

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Abstract

The spliceosome must identify the correct splice sites (SS) and branchsite (BS) used during splicing. E complex is the earliest spliceosome precursor in which the 5' SS and BS are defined. Definition occurs by U1 small nuclear ribonucleoprotein (snRNP) binding the 5' SS and recognition of the BS by the E complex protein (ECP) branchpoint bridging protein (BBP). We have used single molecule fluorescence to study Saccharomyces cerevisiae U1 and BBP interactions with RNAs. E complex is dynamic and permits frequent redefinition of the 5' SS and BS. BBP influences U1 binding at the 5' SS by promoting long-lived complex formation. ECPs facilitate U1 association with RNAs with weak 5' SS and prevent U1 accumulation on RNAs containing hyperstabilized 5' SS. The data reveal a mechanism for how U1 binds the 5' SS and suggest that E complex harnesses this mechanism to stimulate recruitment and retention of U1 on introns.

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Joshua Donald Larson

Department of Biochemistry, University of Wisconsin-Madison, Madison, United States

Competing interests
The authors declare that no competing interests exist.
Aaron A Hoskins

Department of Biochemistry, University of Wisconsin-Madison, Madison, United States

For correspondence
ahoskins@wisc.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-9777-519X

Funding

National Institute of General Medical Sciences (R01 GM112735)

Joshua Donald Larson
Aaron A Hoskins

Greater Milwaukee Foundation

Joshua Donald Larson
Aaron A Hoskins

Arnold and Mabel Beckman Foundation

Joshua Donald Larson
Aaron A Hoskins

Wisconsin Alumni Research Foundation

Joshua Donald Larson
Aaron A Hoskins

National Institutes of Health (R00 GM086471)

Joshua Donald Larson
Aaron A Hoskins

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.