title: The SsgA-like proteins in actinomycetes: small proteins up to a big task.
abstract: Several unique protein families have been identified that play a role in the control of developmental cell division in streptomycetes. The SsgA-like proteins or SALPs, of which streptomycetes typically have at least five paralogues, control specific steps of sporulation-specific cell division in streptomycetes, affecting cell wall-related events such as septum localization and synthesis, thickening of the spore wall and autolytic spore separation. The expression level of SsgA, the best studied SALP, has a rather dramatic effect on septation and on hyphal morphology, which is not only of relevance for our understanding of (developmental) cell division but has also been successfully applied in industrial fermentation, to improve growth and production of filamentous actinomycetes. Recent observations suggest that SsgB most likely is the archetypal SALP, with only SsgB orthologues occurring in all morphologically complex actinomycetes. Here we review 10 years of research on the SsgA-like proteins in actinomycetes and discuss the most interesting regulatory, functional, phylogenetic and applied aspects of this relatively unknown protein family.
authors.affiliation: Microbial Development, Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden, The Netherlands.
authors.forename: Bjørn A
authors.initials: BA
authors.lastname: Traag
authors.forename: Gilles P
authors.initials: GP
authors.lastname: van Wezel
mesh_terms: D039903:Actinobacteria / Q000145:classification / Q000166:cytology* / Q000235:genetics / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002455:Cell Division; D005285:Fermentation; D015964:Gene Expression Regulation, Bacterial; D007218:Industrial Microbiology; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D014158:Transcription, Genetic
chemical_list: D001426:Bacterial Proteins; C414488:ssgA protein, bacterial