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

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.

SUBMITTER: Prieto-Ruiz F 

PROVIDER: S-EPMC10470405 | biostudies-literature | 2023 Sep

REPOSITORIES: biostudies-literature