FlhF Is Required for Swarming Motility and Full Pathogenicity ofBacillus cereus.
Besides sporulation,Bacillus cereuscan undergo a differentiation process in which short swimmer cells become elongated and hyperflagellated swarmer cells that favor migration of the bacterial community on a surface. The functionally enigmatic flagellar protein FlhF, which is the third paralog of the signal recognition particle (SRP) GTPases Ffh and FtsY, is required for swarming in many bacteria. Previous data showed that FlhF is involved in the control of the number and positioning of flagella inB. cereus. In this study,in silicoanalysis ofB. cereusFlhF revealed that this protein presents conserved domains that are typical of SRPs in many organisms and a peculiar N-terminal basic domain. By proteomic analysis, a significant effect of FlhF depletion on the amount of secreted proteins was found with some proteins increased (e.g., B component of the non-hemolytic enterotoxin, cereolysin O, enolase) and others reduced (e.g., flagellin, L2component of hemolysin BL, bacillolysin, sphingomyelinase, PC-PLC, PI-PLC, cytotoxin K) in the extracellular proteome of a ΔflhFmutant. Deprivation of FlhF also resulted in significant attenuation in the pathogenicity of this strain in an experimental model of infection inGalleria mellonellalarvae. Our work highlights the multifunctional role of FlhF inB. cereus, being this protein involved in bacterial flagellation, swarming, protein secretion, and pathogenicity.
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy.
Diletta
D
Mazzantini
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy.
Francesco
F
Celandroni
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy.
Sara
S
Salvetti
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy.
Sokhna A
SA
Gueye
Department of Translational Research and New Technologies in Medicine and Surgery, University of Pisa Pisa, Italy.
Antonella
A
Lupetti
Department of Biology, University of Pisa Pisa, Italy.
Sonia
S
Senesi
Department of Translational Research and New Technologies in Medicine and Surgery, University of PisaPisa, Italy; Research Center Nutraceuticals and Food for Health-Nutrafood, University of PisaPisa, Italy.
Emilia
E
Ghelardi
Bacillus cereus; FlhF; protein secretion; swarming; virulence