Amino acid-level differences in alpha tubulin sequences are uniquely required for meiosis.
Members of the tubulin gene family members are essential components of the cytoskeleton, however functional diversity of tubulin isoforms is poorly understood. Here we addressed this question using  Schizosaccharomyces pombe  as a model system. These yeast encode two α- tubulins,  nda2  and  atb2 , that are very similar at the amino acid level but differ in their roles in organism's survival:  nda2  deletion is lethal, while lack of  atb2  does not interfere with cell viability. Using CRISPR-Cas9 gene editing, we generated a yeast strain expressing  atb2  amino acid sequence utilizing  nda2  codon usage in the native  nda2  locus. Such  nda2 -coded  atb2  (NCA) yeast, unlike  nda2  knockout, were viable and displayed no visible abnormalities in vegetative life cycle. Instead, they displayed strong impairments in sporulation and meiosis, linked to altered balance of several spindle proteins. Our data indicate that  nda2  protein is uniquely required for normal meiosis, and identify novel protein- and nucleotide-level determinants driving functional distinction between closely related tubulin isoforms.
Chen L, Chen X, Kashina A