MicroMech - Nanomechanics of Microbial Infection:Towards Mechanopharmacology

Microbes infect organisms by using proteins in their surface that attach to the surface of the host. Bacteria generally use long filaments called adhesins composed of numerous protein domains that must withstand mechanical forces that go from pico to nanoNewtons. This mechanical resistance is necessary for successful bacterial anchoring to tissues specially in infections such as urinary tract infection or endocarditis, where elevated shear forces exist due to urine and blood flow, respectively. Although it is known that this mechanical resistance is a major factor controlling bacteria adhesion, the exact connection between the mechanical resistance of the different adhesin domains, the adhesion ability and the pathogenicity of bacteria is not fully understood. Understanding such connection would allow combating the initial stage of bacterial infections, i.e., the attachment process. In this proposal, we will study the mechanics of Staphylococcus aureus causing active endocarditis. Endocarditis is an infection of the inner linig of the heart caused by gram-positive bacteria such as Staphylococcus aureus, coagulase-negative Staphylococcus, and Streptococci and Enterococci species. This infection has a worldwide incidence of 5-10 per 100,000 per year with a mortality risk of around 25%. Around one third of infections occurs in heath care settings. The virulence of these bacteria can make them resistant to antibiotics, requiring surgery for removal. We will investigate the role of mechanical forces in the structure and chemistry of two adhesin proteins Clumping factor A (ClfA) and Fibronectin-binding protein A (FnBPA) from S. aureus, as well as their connections to the infection process. We will use an array of techniques to study the nanomechanics of bacterial infections progressively from single molecules to bacteria including strains from actual patients in clinical settings. First, we will use atomic force spectroscopy (AFM) to explore the mechanical rearrangement of ClfA and FnBPA. Second, we will incorporate to our research a technology developed in our lab that incorporates imaging techniques and magnetic nanoparticles that interacts with bacteria allowing mechanical manipulation of a single bacteria using magnetic tweezers. This allows studying the adhesion ability of a single bacteria. Third, we will study clinically relevant S aureus strains from actual patient in critical care units that have been diagnosed with infective endocarditis (IE). These bacteria will be studied in our magnetic tweezers to establish a correlation between their pathogenicity and the mechanical properties of of adhesins ClfA and FnBPA. Finally, we will use bioinformatics to search for molecules that alter the mechanical interactions of these anchoring proteins and that can be potentially used to prevent infections. We have established a procedure to search millions of compounds in chemical libraries to discover small molecules that debilitate the bacterial anchoring proteins which may represents a step towards Mechanopharmacology, a new discipline that aims to target mechanical elements responsible for diseases and disorders.

This project is funded by PID2019-109087RB-I00/MCIN/ AEI /10.13039/501100011033