title: Two novel homologous proteins of Streptomyces coelicolor and Streptomyces lividans are involved in the formation of the rodlet layer and mediate attachment to a hydrophobic surface.
abstract: The filamentous bacteria Streptomyces coelicolor and Streptomyces lividans exhibit a complex life cycle. After a branched submerged mycelium has been established, aerial hyphae are formed that may septate to form chains of spores. The aerial structures possess several surface layers of unknown nature that make them hydrophobic, one of which is the rodlet layer. We have identified two homologous proteins, RdlA and RdlB, that are involved in the formation of the rodlet layer in both streptomycetes. The rdl genes are expressed in growing aerial hyphae but not in spores. Immunolocalization showed that RdlA and RdlB are present at surfaces of aerial structures, where they form a highly insoluble layer. Disruption of both rdlA and rdlB in S. coelicolor and S. lividans (DeltardlAB strains) did not affect the formation and differentiation of aerial hyphae. However, the characteristic rodlet layer was absent. Genes rdlA and rdlB were also expressed in submerged hyphae that were in contact with a hydrophobic solid. Attachment to this substratum was greatly reduced in the DeltardlAB strains. Sequences homologous to rdlA and rdlB occur in a number of streptomycetes representing the phylogenetic diversity of this group of bacteria, indicating a general role for these proteins in rodlet formation and attachment.
authors.affiliation: Groningen Biomolecular Sciences and Biotechnology Institute (GBB), Department of Microbiology, Biological Centre, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
authors.forename: Dennis
authors.initials: D
authors.lastname: Claessen
authors.forename: Han A B
authors.initials: HA
authors.lastname: Wösten
authors.forename: Geertje
authors.initials: G
authors.lastname: van Keulen
authors.forename: Onno G
authors.initials: OG
authors.lastname: Faber
authors.forename: Alexandra M C R
authors.initials: AM
authors.lastname: Alves
authors.forename: Wim G
authors.initials: WG
authors.lastname: Meijer
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism / Q000502:physiology*; D002473:Cell Wall / Q000737:chemistry; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics; D025301:Hyphae / Q000378:metabolism; D011137:Polystyrenes / Q000737:chemistry; D013170:Spores / Q000378:metabolism / Q000648:ultrastructure; D013302:Streptomyces / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D013500:Surface Tension
chemical_list: D001426:Bacterial Proteins; D011137:Polystyrenes; C055447:Streptomyces spore-associated proteins