Divergence of cytokinesis and dimorphism control by myosin II regulatory light chain in fission yeasts

Francisco Prieto-Ruiz; Elisa Gómez-Gil; Jero Vicente-Soler; Alejandro Franco; Teresa Soto; Marisa Madrid; José Cansado

doi:10.1016/j.isci.2023.107611

Divergence of cytokinesis and dimorphism control by myosin II regulatory light chain in fission yeasts

iScience. 2023 Aug 12;26(9):107611. doi: 10.1016/j.isci.2023.107611. eCollection 2023 Sep 15.

Authors

Francisco Prieto-Ruiz¹, Elisa Gómez-Gil², Jero Vicente-Soler¹, Alejandro Franco¹, Teresa Soto¹, Marisa Madrid¹, José Cansado¹

Affiliations

¹ Yeast Physiology Group, Department of Genetics and Microbiology, Campus de Excelencia Internacional de Ámbito Regional (CEIR) Campus Mare Nostrum, Universidad de Murcia, 30071 Murcia, Spain.
² The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.

Abstract

Non-muscle myosin II activation by regulatory light chain (Rlc1^Sp) phosphorylation at Ser35 is crucial for cytokinesis during respiration in the fission yeast Schizosaccharomyces pombe. We show that in the early divergent and dimorphic fission yeast S. japonicus non-phosphorylated Rlc1^Sj regulates the activity of Myo2^Sj and Myp2^Sj heavy chains during cytokinesis. Intriguingly, Rlc1^Sj-Myo2^Sj nodes delay yeast to hyphae onset but are essential for mycelial development. Structure-function analysis revealed that phosphorylation-induced folding of Rlc1^Sp α1 helix into an open conformation allows precise regulation of Myo2^Sp during cytokinesis. Consistently, inclusion of bulky tryptophan residues in the adjacent α5 helix triggered Rlc1^Sp shift and supported cytokinesis in absence of Ser35 phosphorylation. Remarkably, unphosphorylated Rlc1^Sj lacking the α1 helix was competent to regulate S. pombe cytokinesis during respiration. Hence, early diversification resulted in two efficient phosphorylation-independent and -dependent modes of Rlc1 regulation of myosin II activity in fission yeasts, the latter being conserved through evolution.

Keywords: Biological sciences; Cell biology; Molecular biology.