Homologous DNA pairing domain peptides of RecA protein: intrinsic propensity to form β-structures and filaments

A model for the abrogation of the SOS response by an SOS protein: a negatively charged helix in DinI mimics DNA in its interaction with RecA

“…We have shown previously that this is the ssDNA binding region of RecA, as well as the homologous pairing domain (Gardner et al 1995;Malkov and Camerini-Otero 1995;Voloshin et al 1996;Wang et al 1998). As seen in Figure 4A, DinI significantly reduces the binding of ssDNA-WECO complexes to a nitrocellulose filter.…”

“…To prove that the positively charged residues from L2 of RecA and the acidic amino acids from the C-terminal ␣-helix of DinI contribute to the interaction between (Voloshin et al 1996;Wang et al 1998). (A) The whole DinI protein and the DinI 56-78 peptide derived from its C terminus prevent binding of WECO to ssDNA and disassemble the ssDNA-WECO complex.…”

“…All the peptides were prepared on an ABI model 430A synthesizer and purified on a C18 reverse phase column (218TP1022, Vydac). WECO peptide, derived from the loop L2 region of RecA, has been previously described (Voloshin et al 1996;Wang et al 1998). The numbers in the names of the DinIderived peptides correspond to the amino acid positions in the whole protein.…”

?-Hairpin stabilization in a 28-residue peptide derived from the ?-subunit sequence of human chorionic gonadotropin hormone

“…It has been shown that nonmicellar SDS concentrations in the sample medium sometimes have the ability to bring out any latent propensity of the peptides to form ␤-structure. 20,21 Furthermore, high temperature, high sample concentration, and adjusting the pH closer to the isoelectric point of the peptide favor the formation of ␤-structure through the promotion of interstrand interactions. 21 As a tool to study the conformational changes biological molecules undergo in solution and to study the secondary structural types assumed in solution, optical spectroscopic techniques have been used for decades.…”

Calorimetric Analysis of Binding of two Consecutive DNA Strands to RecA Protein Illuminates Mechanism for Recognition Of Homology

“…23,24 Structural changes of macromolecules can thus be detected. Since the flexible L1 and L2 loops of RecA are considered to be involved in DNA binding, [25][26][27][28] an increased degree of organisation of these parts upon DNA binding could be expected, 29 and thus associated with the appearance of a large ΔC p .…”