Solid-state NMR studies of bacterial lipoteichoic acid adsorption on different surfaces

Teichoic acids are important to bacteria for surface adhesion, metal ion coordination, and other biological processes crucial to bacterial survival. In particular, the surface adhesion of teichoic acids plays a crucial role in the formation of Gram-positive biofilms. Biofilms have been implicated as the major cause of various chronic infections. Biofilm formation is essentially a four-step process beginning with the adhesion of bacteria to a surface, followed by the excretion of an extracellular polymeric substance (slime), development and maturation of the biofilm architecture, and finally biofilm spreading through bacterial release. Currently, there is very little molecular level information available for the initial adhesion of bacteria to solid surfaces. Solid-state NMR is ideally suited for the study of these samples, thus we use 31P solid-state NMR experiments to study the initial adhesion of lipoteichoic acid (LTA) to various surfaces. 31P CP-MAS spectra and T1ρ data demonstrate that the structure of LTA changes when adhered to cellulose, cell wall peptidoglycan (PGN), or TiO2. However, when LTA is simultaneously adhered to PGN and TiO2 the observed structure is dependent on the amount of retained water. For LTA on TiO2, we suggest that the alanine and glucosamine groups interact with the surface. However, during simultaneous adhesion to TiO2 and PGN, the glucosamine groups bind to the PGN while the alanine groups bind to the surface. This arrangement traps water between the PGN and TiO2 surface.