Sequential binding of calcium ions to B-repeat domain of SdrD from Staphylococcus aureus (original) (raw)
Related papers
Colloids and surfaces. B, Biointerfaces, 2012
Bacterial adhesion is a threshold event in the formation of biofilms. Several studies on molecular and biochemical aspects have highlighted that the protein matrix of the biofilm is of interest in developing strategies to combat biofouling. The prevalent role of biofilm associated protein (Bap) of Staphylococcus aureus in early adhesion and the putative presence of Ca2+ binding EF hand motif in Bap was the motivation for this study. Biofilm assays (S. aureus strains V329 and M556) were done in micro-titer plates and confocal laser scanning microscopy (CLSM) was used to study the biofilm architecture. The results showed that Ca2+ did not influence planktonic growth of the cultures; however, it modulated the biofilm architecture of S. aureus V329 in a dose dependent manner. Strain M556 was found to be a weak biofilm former and showed no significant change in the presence of Ca2+. When tested with increasing NaCl concentration, there was no reversal of the Bap-dependent Ca2+ inhibition of S. aureus V329 biofilm. This indicates that the interaction of Bap and Ca2+ is not mere electrostatic. CLSM images of V329 biofilm showed reduction in biofilm thickness as well as altered biofilm topography with varying Ca2+ concentrations. The inhibition effect of Ca2+ on strain V329 biofilm disappeared in the presence of chelating agent EDTA at a non-inhibiting concentration (0.15 mM). The paper elaborates the role of Ca2+ in biofilm architecture of S. aureus.
Calcium-Mediated Modulation of Staphylococcal Bacterial Biofilms
Studies on the effect of calcium on Bap-mediated inhibition and modulation of Staphylococcus aureus biofilm was the motivation behind this study. In this study, the effect of calcium on modulation of Staphylococcus aureus biofilm has been studied. Four S. aureus bovine mastitis isolates viz. SA7, SA10, SA33 and bap-positive S. aureus V329 (positive control) along with a bap-isogenic mutant M556 (negative control) were used in this study. PCR was used for detection of bap, biofilm assays were done in microtitre plates and confocal laser scanning microscopy (CLSM) was used to study the biofilm architecture. PCR mediated detection identified SA7, SA10 and SA33 as bap-negative strains. Biofilm assay showed that Ca 2+ inhibited the biofilm growth of SA10 and SAV329 in a dose dependent manner whereas SA7 and SA33 did not show any inhibition. Strain M556 was found to be a weak biofilm former and showed no significant change in the presence of Ca 2+. The planktonic growth study results showed that Ca 2+ did not influence planktonic growth in any of the S. aureus strains except SA10 where ≥ 5 mM Ca 2+ had an inhibitory effect. Interaction of Bap and Ca 2+ was found to be specific, since studies with Mg 2+ did not show any inhibitory effect on V329 biofilm formation. CLSM images of V329, SA7 and SA10 biofilms showed reduction in biofilm thickness as well as altered biofilm topography. The inhibition effect of Ca 2+ on V329 and SA10 biofilms disappeared in the presence of chelating agent EDTA at a sub-minimum inhibitory concentration (0.15 mM). The paper elaborates the role of Ca 2+ in the biofilm architecture of S. aureus.
Calcium Inhibits Bap-Dependent Multicellular Behavior in Staphylococcus aureus
Journal of Bacteriology, 2004
Bap (biofilm-associated protein) is a 254-kDa staphylococcal surface protein implicated in formation of biofilms by staphylococci isolated from chronic mastitis infections. The presence of potential EF-hand motifs in the amino acid sequence of Bap prompted us to investigate the effect of calcium on the multicellular behavior of Bap-expressing staphylococci. We found that addition of millimolar amounts of calcium to the growth media inhibited intercellular adhesion of and biofilm formation by Bap-positive strain V329. Addition of manganese, but not addition of magnesium, also inhibited biofilm formation, whereas bacterial aggregation in liquid media was greatly enhanced by metal-chelating agents. In contrast, calcium or chelating agents had virtually no effect on the aggregation of Bap-deficient strain M556. The biofilm elicited by insertion of bap into the chromosome of a biofilm-negative strain exhibited a similar dependence on the calcium concentration, indicating that the observe...
Microorganisms
Medical device-associated staphylococcal infections are a common and challenging problem. However, detailed knowledge of staphylococcal biofilm dynamics on clinically relevant surfaces is still limited. In the present study, biofilm formation of the Staphylococcus aureus ATCC 25923 strain was studied on clinically relevant materials—borosilicate glass, plexiglass, hydroxyapatite, titanium and polystyrene—at 18, 42 and 66 h. Materials with the highest surface roughness and porosity (hydroxyapatite and plexiglass) did not promote biofilm formation as efficiently as some other selected materials. Matrix-associated poly-N-acetyl-β-(1-6)-glucosamine (PNAG) was considered important in young (18 h) biofilms, whereas proteins appeared to play a more important role at later stages of biofilm development. A total of 460 proteins were identified from biofilm matrices formed on the indicated materials and time points—from which, 66 proteins were proposed to form the core surfaceome. At 18 h, th...