title: The evolution of compositionally and functionally distinct actin filaments.
abstract: The actin filament is astonishingly well conserved across a diverse set of eukaryotic species. It has essentially remained unchanged in the billion years that separate yeast, Arabidopsis and man. In contrast, bacterial actin-like proteins have diverged to the extreme, and many of them are not readily identified from sequence-based homology searches. Here, we present phylogenetic analyses that point to an evolutionary drive to diversify actin filament composition across kingdoms. Bacteria use a one-filament-one-function system to create distinct filament systems within a single cell. In contrast, eukaryotic actin is a universal force provider in a wide range of processes. In plants, there has been an expansion of the number of closely related actin genes, whereas in fungi and metazoa diversification in tropomyosins has increased the compositional variety in actin filament systems. Both mechanisms dictate the subset of actin-binding proteins that interact with each filament type, leading to specialization in function. In this Hypothesis, we thus propose that different mechanisms were selected in bacteria, plants and metazoa, which achieved actin filament compositional variation leading to the expansion of their functional diversity.
authors: School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
authors: Peter W
authors: PW
authors: Gunning
authors: Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673.
authors: Umesh
authors: U
authors: Ghoshdastider
authors: School of Medical Sciences, University of New South Wales, Sydney, NSW, 2052, Australia.
authors: Shane
authors: S
authors: Whitaker
authors: Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673.
authors: David
authors: D
authors: Popp
authors: Institute of Molecular and Cell Biology, A*STAR (Agency for Science, Technology and Research), Biopolis, Singapore 138673 Department of Biochemistry, National University of Singapore, 8 Medical Drive, Singapore 117597 rrobinson@imcb.a-star.edu.sg.
authors: Robert C
authors: RC
authors: Robinson
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D000818:Animals; D001419:Bacteria / Q000378:metabolism; D005075:Biological Evolution; D010802:Phylogeny; D010944:Plants / Q000378:metabolism
chemical_list: D000199:Actins
keywords: Actin; Evolution; Filament; Tropomyosin