title: Actin, actin-related proteins and profilin in diatoms: a comparative genomic analysis.
abstract: Diatoms are heterokont unicellular algae with a widespread distribution throughout all aquatic habitats. Research on diatoms has advanced significantly over the last decade due to available genetic transformation methods and publicly available genome databases. Yet up to now, proteins involved in the regulation of the cytoskeleton in diatoms are largely unknown. Consequently, this work focuses on actin and actin-related proteins (ARPs) encoded in the diatom genomes of Thalassiosira pseudonana, Thalassiosira oceanica, Phaeodactylum tricornutum, Fragilariopsis cylindrus and Pseudo-nitzschia multiseries. Our comparative genomic study revealed that most diatoms possess only a single conventional actin and a small set of ARPs. Among these are the highly conserved cytoplasmic Arp1 protein and the nuclear Arp4 as well as Arp6. Diatom genomes contain genes coding for two structurally different homologues of Arp4 that might serve specific functions. All diatom species examined here lack ARP2 and ARP3 proteins, suggesting that diatoms are not capable of forming the Arp2/3 complex, which is essential in most eukaryotes for actin filament branching and plus-end dynamics. Interestingly, none of the sequenced representatives of the Bacillariophyta phylum code for profilin. Profilin is an essential actin-binding protein regulating the monomer actin pool and is involved in filament plus-end dynamics. This is the first report of organisms not containing profilin.
authors: Section of Plant Cell Biology, Institute of Cellular and Molecular Botany (IZMB), University of Bonn, Kirschallee 1, 53115 Bonn, Germany. Electronic address: charlotte.aumeier@cea.fr.
authors: Charlotte
authors: C
authors: Aumeier
authors: Section of Plant Cell Biology, Institute of Cellular and Molecular Botany (IZMB), University of Bonn, Kirschallee 1, 53115 Bonn, Germany.
authors: Ellen
authors: E
authors: Polinski
authors: Section of Plant Cell Biology, Institute of Cellular and Molecular Botany (IZMB), University of Bonn, Kirschallee 1, 53115 Bonn, Germany.
authors: Diedrik
authors: D
authors: Menzel
mesh_terms: D000199:Actins / Q000235:genetics / Q000378:metabolism*; D017377:Diatoms / Q000235:genetics / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000502:physiology*; D023281:Genomics; D008958:Models, Molecular; D010802:Phylogeny; D051304:Profilins / Q000235:genetics / Q000378:metabolism*; D011487:Protein Conformation
chemical_list: D000199:Actins; D051304:Profilins
keywords: Arp2/3 complex; Arp4; Fragilariopsis cylindrus; Phaeodactylum tricornutum; Pseudo-nitzschia multiseries; Thalassiosira pseudonana