title: Characterization of engineered actin binding proteins that control filament assembly and structure.
abstract: BACKGROUND
  Eukaryotic cells strictly regulate the structure and assembly of their actin filament networks in response to various stimuli. The actin binding proteins that control filament assembly are therefore attractive targets for those who wish to reorganize actin filaments and reengineer the cytoskeleton. Unfortunately, the naturally occurring actin binding proteins include only a limited set of pointed-end cappers, or proteins that will block polymerization from the slow-growing end of actin filaments. Of the few that are known, most are part of large multimeric complexes that are challenging to manipulate.
  
  
  RESULTS
  We describe here the use of phage display mutagenesis to generate of a new class of binding protein that can be targeted to the pointed-end of actin. These proteins, called synthetic antigen binders (sABs), are based on an antibody-like scaffold where sequence diversity is introduced into the binding loops using a novel "reduced genetic code" phage display library. We describe effective strategies to select and screen for sABs that ensure the generated sABs bind to the pointed-end surface of actin exclusively.
  
  
  CONCLUSIONS
  From our set of pointed-end binders, we identify three sABs with particularly useful properties to systematically probe actin dynamics: one protein that caps the pointed end, a second that crosslinks actin filaments, and a third that severs actin filaments and promotes disassembly.
authors.affiliation: Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, Illinois, United States of America.
authors.forename: Crista M
authors.initials: CM
authors.lastname: Brawley
authors.forename: Serdar
authors.initials: S
authors.lastname: Uysal
authors.forename: Anthony A
authors.initials: AA
authors.lastname: Kossiakoff
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Rock
mesh_terms: D008841:Actin Cytoskeleton / Q000378:metabolism*; D000199:Actins / Q000378:metabolism*; D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D002645:Chickens; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000378:metabolism; D019151:Peptide Library; D058105:Polymerization; D011485:Protein Binding
chemical_list: D000199:Actins; D008840:Microfilament Proteins; D009124:Muscle Proteins; D019151:Peptide Library