Brown MT

Edwards AN

Hauwaerts D

Kovach ME

Miller LD

Pereg Gerk L

Pilizota T

Porter SL

Simon R

Sourjik V

Toutain CM

Wadhams GH

Xu Q

Zhulin IB

ABSTRACT
          
            The Che1 chemotaxis-like pathway of
            Azospirillum brasilense
            contributes to chemotaxis and aerotaxis, and it has also been found to contribute to regulating changes in cell surface adhesive properties that affect the propensity of cells to clump and to flocculate. The exact contribution of Che1 to the control of chemotaxis and flocculation in
            A. brasilense
            remains poorly understood. Here, we show that Che1 affects reversible cell-to-cell clumping, a cellular behavior in which motile cells transiently interact by adhering to one another at their nonflagellated poles before swimming apart. Clumping precedes and is required for flocculation, and both processes appear to be independently regulated. The phenotypes of a Δ
            aerC
            receptor mutant and of mutant strains lacking
            cheA1
            ,
            cheY1
            ,
            cheB1
            , or
            cheR1
            (alone or in combination) or with
            che1
            deleted show that Che1 directly mediates changes in the flagellar swimming velocity and that this behavior directly modulates the transient nature of clumping. Our results also suggest that an additional receptor(s) and signaling pathway(s) are implicated in mediating other Che1-independent changes in clumping identified in the present study. Transient clumping precedes the transition to stable clump formation, which involves the production of specific extracellular polysaccharides (EPS); however, production of these clumping-specific EPS is not directly controlled by Che1 activity. Che1-dependent clumping may antagonize motility and prevent chemotaxis, thereby maintaining cells in a metabolically favorable niche.
          </jats:p

Amber Bible

Matthew H. Russell

Gladys Alexandre

Crossref

Journal of Bacteriology

The Azospirillum brasilense Che1 Chemotaxis Pathway Controls Swimming Velocity, Which Affects Transient Cell-to-Cell Clumping

The Azospirillum brasilense Che1 Chemotaxis Pathway Controls Swimming Velocity, Which Affects Transient Cell-to-Cell Clumping

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