title: Theoretical tests of the mechanical protection strategy in protein nanomechanics.
abstract: We provide theoretical tests of a novel experimental technique to determine mechanostability of proteins based on stretching a mechanically protected protein by single-molecule force spectroscopy. This technique involves stretching a homogeneous or heterogeneous chain of reference proteins (single-molecule markers) in which one of them acts as host to the guest protein under study. The guest protein is grafted into the host through genetic engineering. It is expected that unraveling of the host precedes the unraveling of the guest removing ambiguities in the reading of the force-extension patterns of the guest protein. We study examples of such systems within a coarse-grained structure-based model. We consider systems with various ratios of mechanostability for the host and guest molecules and compare them to experimental results involving cohesin I as the guest molecule. For a comparison, we also study the force-displacement patterns in proteins that are linked in a serial fashion. We find that the mechanostability of the guest is similar to that of the isolated or serially linked protein. We also demonstrate that the ideal configuration of this strategy would be one in which the host is much more mechanostable than the single-molecule markers. We finally show that it is troublesome to use the highly stable cystine knot proteins as a host to graft a guest in stretching studies because this would involve a cleaving procedure.
authors.affiliation: Laboratory of Biological Physics, Institute of Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668, Warsaw, Poland.
authors.forename: Mateusz
authors.initials: M
authors.lastname: Chwastyk
authors.forename: Albert
authors.initials: A
authors.lastname: Galera-Prat
authors.forename: Mateusz
authors.initials: M
authors.lastname: Sikora
authors.forename: Àngel
authors.initials: À
authors.lastname: Gómez-Sicilia
authors.forename: Mariano
authors.initials: M
authors.lastname: Carrión-Vázquez
authors.forename: Marek
authors.initials: M
authors.lastname: Cieplak
mesh_terms: D001696:Biomechanical Phenomena; D003553:Cystine / Q000737:chemistry; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins; D003553:Cystine
keywords: coarse grained models; cystine slipknots; pFS vectors; single molecule force spectroscopy; stretching of proteins