title: Ultrastable cellulosome-adhesion complex tightens under load.
abstract: Challenging environments have guided nature in the development of ultrastable protein complexes. Specialized bacteria produce discrete multi-component protein networks called cellulosomes to effectively digest lignocellulosic biomass. While network assembly is enabled by protein interactions with commonplace affinities, we show that certain cellulosomal ligand-receptor interactions exhibit extreme resistance to applied force. Here, we characterize the ligand-receptor complex responsible for substrate anchoring in the Ruminococcus flavefaciens cellulosome using single-molecule force spectroscopy and steered molecular dynamics simulations. The complex withstands forces of 600-750 pN, making it one of the strongest bimolecular interactions reported, equivalent to half the mechanical strength of a covalent bond. Our findings demonstrate force activation and inter-domain stabilization of the complex, and suggest that certain network components serve as mechanical effectors for maintaining network integrity. This detailed understanding of cellulosomal network components may help in the development of biocatalysts for production of fuels and chemicals from renewable plant-derived biomass.
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Constantin
authors.initials: C
authors.lastname: Schoeler
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Klara H
authors.initials: KH
authors.lastname: Malinowska
authors.affiliation: Theoretical and Computational Biophysics Group, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Rafael C
authors.initials: RC
authors.lastname: Bernardi
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Lukas F
authors.initials: LF
authors.lastname: Milles
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Markus A
authors.initials: MA
authors.lastname: Jobst
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Ellis
authors.initials: E
authors.lastname: Durner
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Ott
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Daniel B
authors.initials: DB
authors.lastname: Fried
authors.affiliation: Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel.
authors.forename: Edward A
authors.initials: EA
authors.lastname: Bayer
authors.affiliation: 1] Theoretical and Computational Biophysics Group, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA [2] Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA.
authors.forename: Klaus
authors.initials: K
authors.lastname: Schulten
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Hermann E
authors.initials: HE
authors.lastname: Gaub
authors.affiliation: Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-Universität, 80799 Munich, Germany.
authors.forename: Michael A
authors.initials: MA
authors.lastname: Nash
mesh_terms: D018533:Biomass; D001703:Biophysics; D002118:Calcium / Q000737:chemistry; D002384:Catalysis; D002448:Cell Adhesion; D044603:Cellulosomes / Q000737:chemistry*; D003198:Computer Simulation; D006860:Hydrogen Bonding; D007477:Ions; D008024:Ligands; D018625:Microscopy, Atomic Force; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D016011:Normal Distribution; D011485:Protein Binding; D011487:Protein Conformation; D017510:Protein Folding; D045857:Ruminococcus / Q000737:chemistry*
chemical_list: D007477:Ions; D008024:Ligands; D002118:Calcium