Identification of a new type 6 secretion system effector of Pseudomonas fluorescens MFE01 involved in bacterial motility inhibition

International audienc

Identification of a new type 6 secretion system effector of Pseudomonas fluorescens MFE01 involved in bacterial motility inhibition

International audienc

Contribution of the <i>Pseudomonas fluorescens</i> MFE01 Type VI Secretion System to Biofilm Formation

<div><p>Type VI secretion systems (T6SSs) are widespread in Gram-negative bacteria, including <i>Pseudomonas</i>. These macromolecular machineries inject toxins directly into prokaryotic or eukaryotic prey cells. Hcp proteins are structural components of the extracellular part of this machinery. We recently reported that MFE01, an avirulent strain of <i>Pseudomonas fluorescens</i>, possesses at least two <i>hcp</i> genes, <i>hcp1</i> and <i>hcp2</i>, encoding proteins playing important roles in interbacterial interactions. Indeed, <i>P</i>. <i>fluorescens</i> MFE01 can immobilise and kill diverse bacteria of various origins through the action of the Hcp1 or Hcp2 proteins of the T6SS. We show here that another Hcp protein, Hcp3, is involved in killing prey cells during co-culture on solid medium. Even after the mutation of <i>hcp1</i>, <i>hcp2</i>, or <i>hcp3</i>, MFE01 impaired biofilm formation by MFP05, a <i>P</i>. <i>fluorescens</i> strain isolated from human skin. These mutations did not reduce <i>P</i>. <i>fluorescens</i> MFE01 biofilm formation, but the three Hcp proteins were required for the completion of biofilm maturation. Moreover, a mutant with a disruption of one of the unique core component genes, MFE01Δ<i>tssC</i>, was unable to produce its own biofilm or inhibit MFP05 biofilm formation. Finally, MFE01 did not produce detectable N-acyl-homoserine lactones for quorum sensing, a phenomenon reported for many other <i>P</i>. <i>fluorescens</i> strains. Our results suggest a role for the T6SS in communication between bacterial cells, in this strain, under biofilm conditions.</p></div

Contribution of the Pseudomonas fluorescens MFE01 Type VI Secretion System to Biofilm Formation.

National audienc

Type VI secretion system and expression of flagellar class IV genes in the Pseudomonas fluorescens MFE01 strain

International audienc

Type VI secretion system and expression of flagellar class IV genes in the Pseudomonas fluorescens MFE01 strain

International audienc

Type VI secretion system and expression of flagellar class IV genes in the Pseudomonas fluorescens MFE01 strain

International audienc

Type VI secretion system and expression of flagellar class IV genes in the Pseudomonas fluorescens MFE01 strain

International audienc

Type VI secretion system and expression of flagellar class IV genes in the Pseudomonas fluorescens MFE01 strain

International audienc

Type VI secretion system and expression of flagellar class IV genes in the Pseudomonas fluorescens MFE01 strain

International audienc