Staphylococcus aureus; extracellular DNA; biofilms; GdpS; fluorescence microscopy
Fischer Adrien, Kambara Kumiko, Meyer Hanna, Stenz Ludwig, Bonetti Eve-Julie, Girard Myriam, Lalk Michael, François Patrice, Schrenzel Jacques (2014), GdpS contributes to Staphylococcus aureus biofilm formation by regulation of eDNA release, in International Journal of Medical Microbiology
, (304), 284-299.
S. aureus is a ubiquitous Gram-positive bacterium, able to exist on inanimate objects as well as in a variety of niches, such as the skin, mucous membranes, blood, or bones. During its lifetime, a single bacterium can travel from one location to another, exposing the bacteria to multiple environments. These transitions are very likely to require quick switches from a unicellular planktonic lifestyle to settle multicellular communities commonly referred to as biofilms.Our previous research permitted to identify 38 biofilm-deficient mutants by screening a transposition library. The characterization of a subset of such mutants revealed the role of (i) SA1885, a DEAD-box protein linking biofilms and virulence through mRNA degradation in the degradosome, (ii) codY regulating glucidic biofilm formation, and (iii) the contribution of SA0701, or gdpS, acting on biofilm biogenesis by controlling extracellular DNA (eDNA) deposition. Surprisingly this action is not mediated by c-di-GMP signaling but by a novel pathway. Our objectives are therefore to characterize eDNA accumulation that we have already shown to be cell-lysis independent and supposed to be independent from holin-mediated autolysis during the early stages of biofilm formation. This proposal aims therefore at analyzing the building up of eDNA in early biofilms, by describing its structural and functional roles and by focusing on the regulation of eDNA deposition. A better knowledge of such regulation would not only constitute a major achievement in the field but also provide potential targets for innovative antimicrobial strategies.In summary, molecular and genetic tools developed during previous grant applications will be applied to characterize in details the mechanism of action of one particular gene involved in S. aureus biofilm development. We will therefore address the general question whether biofilm formation represents a developmental program of coordinated gene expression and study the genetic diversification and selection shaping biofilm evolution.