The role of structural proteins in development and attachment of Streptomyces coelicolor

PhD ceremony: Mr. W. de Jong, 16.15 uur, Academiegebouw, Broerstraat 5, Groningen

Thesis: The role of structural proteins in development and attachment of Streptomyces coelicolor

Promotor(s): prof. L. Dijkhuizen, prof. H.A.B. Wösten

Faculty: Mathematics and Natural Sciences

Wouter de Jong studied proteins of streptomycetes. Streptomycetes are soil-dwelling filamentous bacteria that undergo complex morphological changes during their life cycle. Spore germination results in the formation of a network of vegetative hyphae, called a feeding mycelium, that colonizes a substrate. As soon as nutrients are depleted, hyphae grow into the air to produce aerial hyphae that eventually septate into chains of spores. Streptomyces also undergoes morphological changes when hyphae attach to a surface. During attachment, an intercellular network of fimbriae is formed. Attachment may be important for the effective degradation of substrates, colonization of specific niches such as the cuticle of leaf-cutting ants and the initiation of infection processes by pathogenic streptomycetes.

The formation of aerial hyphae is accompanied by a change in the surface hydrophobicity of hyphae. Expression of the genes encoding the proteins that cover the cell surface is controlled by the sky pathway. This regulatory mechanisms, which is activated as soon as aerial growth commences, was proposed to activate expression of many aerial-hyphae specific expression. The targets of the sky pathway are the subject of hhis thesis, with emphasis on the cell wall-associated protein NepA and the peptide SapB. The data presented in his thesis show that genes controlled by the sky pathway are also activated during attachment.