Binding modes of cyclic AMP and environments of tryptophan residues in 1:1 and 1:2 complexes of cyclic AMP receptor protein and cyclic AMP

Abstract

Cyclic AMP (cAMP) receptor protein (CRP) forms 1:1 and 1:2 complexes with cAMP, and the former complex is considered to be the most active form of CRP in binding to specific DNA sequences and in modulating gene transcription by RNA polymerases. We examine the cAMP binding modes and structural changes of CRP upon cAMP binding by UV resonance Raman spectroscopy. The Raman spectra of CRP-(cAMP)(1) and CRP-(cAMP)(2) extracted from those of CRP-cAMP mixtures at varied mixing ratios clearly show that the hydrogen bonding state and the conformation of cAMP in both complexes in solution are very similar to those found in the X-ray crystal structure of CRP-(cAMP)(2), which is evidence that the cAMP binding mode does not differ between the two complexes. The environmental hydrophobicity of Trp85 monitored by UV resonance Raman intensity shows a significant decrease upon binding of the first cAMP molecule, whereas no further change occurs in the second cAMP binding step. The environmental change of Trp85 suggests an opening of the cleft between the N-terminal cAMP and C-terminal DNA binding domains in the process of CRP activation by binding of a single cAMP molecule.

A Multidisciplinary Approach to Probing Enthalpy–Entropy Compensation and the Interfacial Mobility Model

“…50 Additionally, the 1360 cm −1 is not always discernible in non-resonance spectra, 51 even if readily apparent in the resonance Raman spectra. 48,49 …”

Cyclic AMP Receptor Protein Acts as a Transcription Regulator in Response to Stresses in Deinococcus radiodurans

“…Crystallographic studies of E . coli CRP have been performed to determine the structure of a CRP-cAMP complex, its target DNA, and the carboxyl-terminal domain of the RNA polymerase (RNAP) α-subunit[ 15 – 19 ]. It is shown that CRP contains a helix-turn-helix DNA-binding motif in its carboxyl-terminal domain and a cAMP-binding site in its amino-terminal domain[ 20 – 22 ].…”

Successful treatment of distal coronary guidewire‐induced perforation with balloon catheter delivery of intracoronary thrombin

“…The downshifted W6 band serves as a marker of N 1 ‐deuteration in visible Raman spectra 5, 23. In UV resonance Raman spectra excited at 229 nm, the W4 band can be detected but the W6 band is not clear 27, 38, 39. The wavenumbers of the Wd4 (≈1445 cm −1 ) and Wd5 (≈1405 cm −1 ) bands of Trp‐ d 5 also depend on hydrogen bonding in a way similar to that of the W4 and W6 bands of Trp 8.…”