title: Characterisation of Schizosaccharomyces pombe α-actinin.
abstract: The actin cytoskeleton plays a fundamental role in eukaryotic cells. Its reorganization is regulated by a plethora of actin-modulating proteins, such as a-actinin. In higher organisms, α-actinin is characterized by the presence of three distinct structural domains: an N-terminal actin-binding domain and a C-terminal region with EF-hand motif separated by a central rod domain with four spectrin repeats. Sequence analysis has revealed that the central rod domain of α-actinin from the fission yeast Schizosaccharomyces pombe consists of only two spectrin repeats. To obtain a firmer understanding of the structure and function of this unconventional α-actinin, we have cloned and characterized each structural domain. Our results show that this a-actinin isoform is capable of forming dimers and that the rod domain is required for this. However, its actin-binding and cross-linking activity appears less efficient compared to conventional α-actinins. The solved crystal structure of the actin-binding domain indicates that the closed state is stabilised by hydrogen bonds and a salt bridge not present in other α-actinins, which may reduce the affinity for actin.
authors.affiliation: Cell Biology Laboratory, School of Biochemistry and Cell Biology, BioScience Institute, University College Cork , Cork , Ireland.
authors.forename: Barbara
authors.initials: B
authors.lastname: Addario
authors.affiliation: Department of Molecular Biology, UmeåUniversity , Umeå , Sweden.
authors.forename: Linda
authors.initials: L
authors.lastname: Sandblad
authors.affiliation: Department of Chemistry, Biological Chemistry , Umeå , Sweden.
authors.forename: Karina
authors.initials: K
authors.lastname: Persson
authors.affiliation: Department of Chemistry, Biological Chemistry , Umeå , Sweden.
authors.forename: Lars
authors.initials: L
authors.lastname: Backman
keywords: Actin-binding protein; Schizosaccharomyces pombe; Spectrin repeat; α-actinin