title: The inactive form of recA protein: the 'compact' structure.
abstract: When recA protein is enzymatically inactive in vitro, it adopts a more compact helical polymer form than that of the active protein polymerized onto DNA in the presence of ATP. Here we describe some aspects of this structure. By cryo-electron microscopy, a pitch of 76 A is found for both the self-polymer and the inactive complex with ssDNA. A smaller pitch of 64 A is observed in conventional electron micrographs. The contour length of complexes with ssDNA was used to estimate the binding stoichiometry in the compact complex, 6 +/- 1 nt/recA. In addition, the compact structure was observed in vivo in Escherichia coli: inclusion bodies produced upon induction of recA expression in an overproducing strain have a fibrous morphology with the structural parameters of the compact polymer.
authors.affiliation: European Molecular Biology Laboratory, Grenoble Outstation, France.
authors.forename: R W
authors.initials: RW
authors.lastname: Ruigrok
authors.forename: B
authors.initials: B
authors.lastname: Bohrmann
authors.forename: E
authors.initials: E
authors.lastname: Hewat
authors.forename: A
authors.initials: A
authors.lastname: Engel
authors.forename: E
authors.initials: E
authors.lastname: Kellenberger
authors.forename: E
authors.initials: E
authors.lastname: DiCapua
mesh_terms: D017122:Bacteriophage T4 / Q000378:metabolism / Q000648:ultrastructure; D004277:DNA, Single-Stranded / Q000378:metabolism / Q000648:ultrastructure; D004926:Escherichia coli / Q000378:metabolism / Q000648:ultrastructure; D005615:Freezing; D008854:Microscopy, Electron / Q000379:methods; D011487:Protein Conformation; D011938:Rec A Recombinases / Q000378:metabolism / Q000648:ultrastructure*
chemical_list: D004277:DNA, Single-Stranded; D011938:Rec A Recombinases