The transactivation region of the fis protein that controls site-specific DNA inversion contains extended mobile beta-hairpin arms.
The Fis protein regulates site-specific DNA inversion catalyzed by a family of DNA invertases when bound to a cis-acting recombinational enhancer. As is often found for transactivation domains, previous crystal structures have failed to resolve the conformation of the N-terminal inversion activation region within the Fis dimer. A new crystal form of a mutant Fis protein now reveals that the activation region contains two beta-hairpin arms that protrude over 20 A from the protein core. Saturation mutagenesis identified the regulatory and structurally important amino acids. The most critical activating residues are located near the tips of the beta-arms. Disulfide cross-linking between the beta-arms demonstrated that they are highly flexible in solution and that efficient inversion activation can occur when the beta-arms are covalently linked together. The emerging picture for this regulatory motif is that contacts with the recombinase at the tip of the mobile beta-arms activate the DNA invertase in the context of an invertasome complex.
Safo
M K
MK
Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan 11529, Republic of China.
Yang
W Z
WZ
Corselli
L
L
Cramton
S E
SE
Yuan
H S
HS
Johnson
R C
RC
D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D003545:Cysteine / Q000737:chemistry; D004252:DNA Mutational Analysis; D004254:DNA Nucleotidyltransferases / Q000378:metabolism; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D017433:Protein Structure, Secondary; D011995:Recombination, Genetic; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
D002352:Carrier Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; D015534:Trans-Activators; D004254:DNA Nucleotidyltransferases; C059997:Hin recombinase; D003545:Cysteine