The inactive form of recA protein: the 'compact' structure.
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.
Ruigrok
R W
RW
European Molecular Biology Laboratory, Grenoble Outstation, France.
Bohrmann
B
B
Hewat
E
E
Engel
A
A
Kellenberger
E
E
DiCapua
E
E
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*
D004277:DNA, Single-Stranded; D011938:Rec A Recombinases