title: Adhesion molecules from the diatom Phaeodactylum tricornutum (Bacillariophyceae): genomic identification by amino-acid profiling and in vivo analysis.
abstract: Cell adhesion molecules (CAMs) are important in prokaryotes and eukaryotes for cell-cell and cell-substratum interactions. The characteristics of adhesive proteins in the model diatom Phaeodactylum tricornutum were investigated by bioinformatic analysis and in vivo characterization. Bioinformatic analysis of the protein coding potential of the P. tricornutum genome used an amino-acid profile that we developed as a new system to identify uncharacterized or novel CAMs. Putative diatom CAMs were identified and seven were characterized in vivo, by generation of transgenic diatom lines overexpressing genes encoding C-terminal yellow fluorescent protein (YFP) fusion proteins. Three of these selected genes encode proteins with weak similarity to characterized proteins, a c-type lectin and two fasciclins, whereas the others are novel. The resultant cell lines were investigated for alterations in their adhesive ability. Whole cell-substratum adhesion strength was measured in a fully turbulent flow chamber, while atomic force microscopy was used to quantify the relative frequency of adhesion, as well as the length and strength of single molecules in the secreted mucilage. Finally, quartz crystal microbalance analysis characterized the visco-elastic properties and interaction of the mucilage-substratum interface. These combined studies revealed a range of phenotypes affecting adhesion, and led to the identification of candidate proteins involved in diatom adhesion. In summary, our study has for the first time combined bioinformatics and molecular physiological studies to provide new insights into diatom adhesive molecules.
authors.affiliation: School of Botany, The University of Melbourne, Parkville, 3010, Victoria, Australia.|Environmental and Evolutionary Genomics Section, CNRS UMR8197 INSERM U1024, Institut de Biologie de l'Ecole Normale Supérieure, 46 rue d'Ulm 75230, Paris Cedex 05, France.
authors.forename: Anusuya
authors.initials: A
authors.lastname: Willis
authors.affiliation: School of Botany, The University of Melbourne, Parkville, 3010, Victoria, Australia.
authors.forename: Maeve
authors.initials: M
authors.lastname: Eason-Hubbard
authors.affiliation: School of Botany, The University of Melbourne, Parkville, 3010, Victoria, Australia.
authors.forename: Oliver
authors.initials: O
authors.lastname: Hodson
authors.affiliation: Environmental and Evolutionary Genomics Section, CNRS UMR8197 INSERM U1024, Institut de Biologie de l'Ecole Normale Supérieure, 46 rue d'Ulm 75230, Paris Cedex 05, France.
authors.forename: Uma
authors.initials: U
authors.lastname: Maheswari
authors.affiliation: Environmental and Evolutionary Genomics Section, CNRS UMR8197 INSERM U1024, Institut de Biologie de l'Ecole Normale Supérieure, 46 rue d'Ulm 75230, Paris Cedex 05, France.
authors.forename: Chris
authors.initials: C
authors.lastname: Bowler
authors.affiliation: School of Botany, The University of Melbourne, Parkville, 3010, Victoria, Australia.
authors.forename: Richard
authors.initials: R
authors.lastname: Wetherbee
keywords: Gateway cloning; adhesion; atomic force microscopy; biofouling; bioinformatics; cell adhesion molecules; diatom; gene identification; quartz crystal microbalance