title: SiaA and SiaD are essential for inducing autoaggregation as a specific response to detergent stress in Pseudomonas aeruginosa.
abstract: Cell aggregation is a stress response and serves as a survival strategy for Pseudomonas aeruginosa strain PAO1 during growth with the toxic detergent Na-dodecylsulfate (SDS). This process involves the psl operon and is linked to c-di-GMP signalling. The induction of cell aggregation in response to SDS was studied. Transposon and site-directed mutagenesis revealed that the cupA-operon and the co-transcribed genes siaA (PA0172) and siaD (PA0169) were essential for SDS-induced aggregation. While siaA encodes a putative membrane protein with a HAMP and a PP2C-like phosphatase domain, siaD encodes a putative diguanylate cyclase involved in the biosynthesis of c-di-GMP. Complementation studies uncovered that the loss of SDS-induced aggregation in the formerly isolated spontaneous mutant strain N was caused by a non-functional siaA allele. DNA-microarray analysis of SDS-grown cells revealed consistent activation of eight genes, including cupA1, with known or presumptive important functions in cell aggregation in the parent strain compared with non-aggregating siaA and siaD mutants. A siaAD-dependent increase of cupA1 mRNA levels in SDS-grown cells was also shown by Northern blots. These results clearly demonstrate that SiaAD are essential for inducing cell aggregation as a specific response to SDS and suggest that they are responsible for perceiving and transducing SDS-related stress.
authors.affiliation: Universität Konstanz, Fachbereich Biologie, Mikrobielle Okologie, Fach M654, 78457 Konstanz, Germany.
authors.forename: Janosch
authors.initials: J
authors.lastname: Klebensberger
authors.forename: Antoinette
authors.initials: A
authors.lastname: Birkenmaier
authors.forename: Robert
authors.initials: R
authors.lastname: Geffers
authors.forename: Staffan
authors.initials: S
authors.lastname: Kjelleberg
authors.forename: Bodo
authors.initials: B
authors.lastname: Philipp
mesh_terms: D003902:Detergents / Q000633:toxicity; D015964:Gene Expression Regulation, Bacterial / Q000187:drug effects; D005798:Genes, Bacterial; D009154:Mutation; D011550:Pseudomonas aeruginosa / Q000235:genetics* / Q000378:metabolism; D012967:Sodium Dodecyl Sulfate / Q000633:toxicity; D013312:Stress, Physiological / Q000187:drug effects*
chemical_list: D003902:Detergents; D012967:Sodium Dodecyl Sulfate