Characterization of cell surface and extracellular matrix remodeling of Azospirillum brasilense chemotaxis-like 1 signal transduction pathway mutants by atomic force microscopy.
Amanda N. Edwards, Piro Siuti, Amber N. Bible, Gladys Alexandre, Scott T. Retterer, Mitchel J. Doktycz, and Jennifer L. Morrell-Falvey
01 January 2011, FEMS Microbiol Lett. 314(2):131-9; doi: 10.1111/j.1574-6968.2010.02156.x. Epub 2010 Nov 24.
To compete in complex microbial communities, bacteria must sense environmental changes and adjust cellular functions for optimal growth. Chemotaxis-like signal transduction pathways are implicated in the regulation of multiple behaviors in response to changes in the environment, including motility patterns, exopolysaccharide production, and cell-to-cell interactions. In Azospirillum brasilense, cell surface properties, including exopolysaccharide production, are thought to play a direct role in promoting flocculation. Recently, the Che1 chemotaxis-like pathway from A. brasilense was shown to modulate flocculation, suggesting an associated modulation of cell surface properties. Using atomic force microscopy, distinct changes in the surface morphology of flocculating A. brasilense Che1 mutant strains were detected. Whereas the wild-type strain produces a smooth mucosal extracellular matrix after 24 h, the flocculating Che1 mutant strains produce distinctive extracellular fibril structures. Further analyses using flocculation inhibition, lectin-binding assays, and comparison of lipopolysaccharides profiles suggest that the extracellular matrix differs between the cheA1 and the cheY1 mutants, despite an apparent similarity in the macroscopic floc structures. Collectively, these data indicate that disruption of the Che1 pathway is correlated with distinctive changes in the extracellular matrix, which likely result from changes in surface polysaccharides structure and/or composition.
Edwards AN, Siuti P, Bible AN, Alexandre G, Retterer ST, Doktycz MJ, Morrell-Falvey JL. Characterization of cell surface and extracellular matrix remodeling of Azospirillum brasilense chemotaxis-like 1 signal transduction pathway mutants by atomic force microscopy. FEMS Microbiol Lett. 2011 Jan;314(2):131-9. doi: 10.1111/j.1574-6968.2010.02156.x. Epub 2010 Nov 24. PubMed PMID: 21105907.