Natural circularly permuted group II introns in bacteria produce RNA circles

Adam Roth; Zasha Weinberg; Koen Vanderschuren; Mitchell H Murdock; Ronald R Breaker

doi:10.1016/j.isci.2021.103431

Natural circularly permuted group II introns in bacteria produce RNA circles

iScience. 2021 Nov 13;24(12):103431. doi: 10.1016/j.isci.2021.103431. eCollection 2021 Dec 17.

Authors

Adam Roth^{1

2}, Zasha Weinberg^{1

2}, Koen Vanderschuren¹, Mitchell H Murdock¹, Ronald R Breaker^{1

2

3}

Affiliations

¹ Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA.
² Howard Hughes Medical Institute, Yale University, New Haven, CT 06520-8103, USA.
³ Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520-8103, USA.

Abstract

Group II self-splicing introns are large structured RNAs that remove themselves from transcripts while simultaneously sealing the resulting gaps. Some representatives can subsequently reverse splice into DNA, accounting for their pervasive distribution in bacteria. The catalytically active tertiary structure of each group II intron is assembled from six domains that are arranged in a conserved order. Here, we report structural isomers of group II introns, called CP group II ribozymes, wherein the characteristic order of domains has been altered. Domains five and six, which normally reside at the 3' end of group II introns, instead occupy the 5' end to form circularly permuted variants. These unusual group II intron derivatives are catalytically active and generate large linear branched and small circular RNAs, reaction products that are markedly different from those generated by canonical group II introns. The biological role of CP group II ribozymes is currently unknown.

Keywords: Bioinformatics; Biological sciences; Molecular biology; Structural biology.