Sequential binding of calcium ions to the B-repeat domain of SdrD from Staphylococcus aureus

Andrei A Roman (1) , François Devred (2) , Vladimir M Lobatchov (3) , Alexander A Makarov (3) , Vincent Peyrot (2) , Aslan A Kubatiev (4) , Philipp O Tsvetkov (2, 4)

1 Institute of Computer Science [Krakow]
2 CRO2 - Centre de Recherches en Oncologie biologique et Oncopharmacologie
3 ISTC - Engelhardt Institute of Molecular Biology
4 Institute of General Pathology and Pathophysiology

Biofilms of live bacteria forming on medical devices and implants contribute significantly to bacterial blood dissemination and to the spread of nosocomial infections. Cell surface SdrD protein plays a key role in the attachment of Staphylococcus aureus to the extracellular matrix (ECM) and in the formation of biofilm. SdrD binds calcium ions using its B1–B5 region bearing EF-hand Ca-binding sites, leading to conformational changes in the structure of SdrD. This alters the distance between the bacterial surface and the ECM-interacting domain of SdrD in a spring-like fashion, participating in bacterial attachment. In this study we investigated calcium binding to EF-hand sites of SdrD using isothermal titration calorimetry and determined the impact of this process on SdrD's thermodynamic stability. This allowed us to propose a model of B1–B5 reorganization upon binding of calcium and to get new insight into the molecular mechanism of SdrD's action.

Keywords: Staphylococcus aureus; calcium binding; isothermal titration calorimetry; differential scanning calorimetry; protein thermal denaturation; sequential binding model

Domains: Bacteriology

Andrei A Roman, François Devred, Vladimir M Lobatchov, Alexander A Makarov, Vincent Peyrot, et al.. Sequential binding of calcium ions to the B-repeat domain of SdrD from Staphylococcus aureus. Canadian Journal of Microbiology, 2016, 62 (2), pp.123-129. ⟨10.1139/cjm-2015-0580⟩. ⟨hal-01478554⟩