Expansion and transformation of the minor spliceosomal system in the slime mold Physarum polycephalum

Larue, G.; Elias, M.; Roy, S. W.

doi:10.1101/2020.10.12.336362

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bioRxiv · 10.1101/2020.10.12.336362

Expansion and transformation of the minor spliceosomal system in the slime mold Physarum polycephalum

Larue, G.·Elias, M.·Roy, S. W.

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Abstract

Spliceosomal introns interrupt nuclear genes and are removed from RNA transcripts ("spliced") by machinery called spliceosomes. While the vast majority of spliceosomal introns are removed by the so-called major spliceosome, diverse eukaryotes also contain a mysterious second form, the minor spliceosome, and associated introns [1-3]. In all characterized species, minor introns are distinguished by several features, including being rare in the genome ([~]0.5% of all introns) [4-6], containing extended evolutionary-conserved splicing sites [4,5,7,8], being generally ancient [9,10] and being inefficiently spliced [11-13]. Here, we report a remarkable exception in the slime mold Physarum polycephalum. The P. polycephalum genome contains > 20,000 minor introns--25 times more than any other species--with transformed splicing signals that have co-evolved with the spliceosome due to massive gain of efficiently spliced minor introns. These results reveal an unappreciated dynamism of minor spliceosomal introns and spliceosomal introns in general.

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Larue, G., Elias, M., Roy, S. W.. 2020-10-12. Expansion and transformation of the minor spliceosomal system in the slime mold Physarum polycephalum. https://doi.org/10.1101/2020.10.12.336362

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