title: NepA is a structural cell wall protein involved in maintenance of spore dormancy in Streptomyces coelicolor.
abstract: Streptomycetes have a complex morphogenetic programme culminating in the formation of aerial hyphae that develop into chains of spores. After spore dispersal, environmental signals trigger dormant spores to germinate to establish a new colony. We here compared whole genome expression of a wild-type colony of Streptomyces coelicolor forming aerial hyphae and spores with that of the chp null mutant that forms few aerial structures. This revealed that expression of 244 genes was significantly altered, among which genes known to be involved in development. One of the genes that was no longer expressed in the DeltachpABCDEFGH mutant was nepA, which was previously shown to be expressed in a compartment connecting the substrate mycelium with the sporulating parts of the aerial mycelium. We here show that expression is also detected in developing spore chains, where NepA is secreted to end up as a highly insoluble protein in the cell wall. Germination of spores of a nepA deletion mutant was faster and more synchronous, resulting in colonies with an accelerated morphogenetic programme. Crucially, spores of the DeltanepA mutant also germinated in water, unlike those of the wild-type strain. Taken together, NepA is the first bacterial structural cell wall protein that is important for maintenance of spore dormancy under unfavourable environmental conditions.
authors.affiliation: Groningen Biomolecular Sciences and Biotechnology Institute, Department of Microbiology, University of Groningen, Kerklaan 30, 9751 NN Haren, The Netherlands.
authors.forename: Wouter
authors.initials: W
authors.lastname: de Jong
authors.forename: Angel
authors.initials: A
authors.lastname: Manteca
authors.forename: Jesus
authors.initials: J
authors.lastname: Sanchez
authors.forename: Giselda
authors.initials: G
authors.lastname: Bucca
authors.forename: Colin P
authors.initials: CP
authors.lastname: Smith
authors.forename: Lubbert
authors.initials: L
authors.lastname: Dijkhuizen
authors.forename: Dennis
authors.initials: D
authors.lastname: Claessen
authors.forename: Han A B
authors.initials: HA
authors.lastname: Wösten
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002473:Cell Wall / Q000378:metabolism*; D003001:Cloning, Molecular; D004269:DNA, Bacterial / Q000235:genetics; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D016680:Genome, Bacterial; D025301:Hyphae / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D013171:Spores, Bacterial / Q000235:genetics / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial