Since I joined the Fernandez lab, I have been involved in projects dealing with protein mechanics. We described that intramolecular isopeptide bonds in adhesins of gram-positive bacteria confer unprecedented mechanical stability. We have also implemented an assay based on mechanical uncaging of cysteine residues that allowed us to monitor in real-time the isomerization of disulfide bonds in proteins. My current research projects try to bridge the gap between Protein Mechanics and Biology. I want to know how the mechanical properties of proteins determine the macroscopic behavior of tissues and cells, with a focus on cardiac muscle and bacterial infection. Pili from Gram-positive bacteria are natural polyproteins that have to overcome high mechanical stress in vivo to endure in tissues and cause infections. We are trying to understand how mechanically defective pili are challenged when adhering under mechanical stress. Our strategy may be useful to design new antibiotics that interfere with the attachment of pathogenic bacteria. Regarding muscle elasticity, we have recently discovered that modification of buried residues in the giant protein titin results in increased elasticity of cardiac cells. We propose that this novel mechanism to control elasticity may be also found in other tissues.