SiaA and SiaD are essential for inducing autoaggregation as a specific response to detergent stress in Pseudomonas aeruginosa
Article first published online: 23 JUL 2009
© 2009 Society for Applied Microbiology and Blackwell Publishing Ltd
Volume 11, Issue 12, pages 3073–3086, December 2009
How to Cite
Klebensberger, J., Birkenmaier, A., Geffers, R., Kjelleberg, S. and Philipp, B. (2009), SiaA and SiaD are essential for inducing autoaggregation as a specific response to detergent stress in Pseudomonas aeruginosa. Environmental Microbiology, 11: 3073–3086. doi: 10.1111/j.1462-2920.2009.02012.x
- Issue published online: 1 DEC 2009
- Article first published online: 23 JUL 2009
- Received 6 November, 2008; accepted 20 June, 2009.
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.