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GoLoco motif proteins binding to Galpha(i1): insights from molecular simulations.

ABSTRACT: Molecular dynamics simulations, computational alanine scanning and sequence analysis were used to investigate the structural properties of the Galpha(i1)/GoLoco peptide complex. Using these methodologies, binding of the GoLoco motif peptide to the Galpha(i1) subunit was found to restrict the relative movement of the helical and catalytic domains in the Galpha(i1) subunit, which is in agreement with a proposed mechanism of GDP dissociation inhibition by GoLoco motif proteins. In addition, the results provide further insights into the role of the "Switch IV" region located within the helical domain of Galpha, the conformation of which might be important for interactions with various Galpha partners.

SUBMITTER: Khafizov K

PROVIDER: S-EPMC2847169 | biostudies-literature | 2009 Dec

REPOSITORIES: biostudies-literature

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GoLoco motif proteins binding to Galpha(i1): insights from molecular simulations.

Khafizov Kamil K

Journal of molecular modeling 20090514 12

Molecular dynamics simulations, computational alanine scanning and sequence analysis were used to investigate the structural properties of the Galpha(i1)/GoLoco peptide complex. Using these methodologies, binding of the GoLoco motif peptide to the Galpha(i1) subunit was found to restrict the relative movement of the helical and catalytic domains in the Galpha(i1) subunit, which is in agreement with a proposed mechanism of GDP dissociation inhibition by GoLoco motif proteins. In addition, the res ...[more]

PMID: 19437048

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Project description:Quinine's ability to bind DNA and potentially inhibit transcription and translation has been examined as a mode of action for its antimalarial activity. UV absorption and fluorescence-based studies have lacked the chemical specificity to develop an unambiguous molecular-level picture of the binding interaction. To address this, we use Raman spectroscopy and molecular dynamics (MD) to investigate quinine-DNA interactions. We demonstrate that quinine's strongest Raman band in the fingerprint region, which derives from a symmetric stretching mode of the quinoline ring, is highly sensitive to the local chemical environment and pH. The frequency shifts observed for this mode in solvents of varying polarity can be explained in terms of the Stark effect using a simple Onsager solvation model, indicating that the vibration reports on the local electrostatic environment. However, specific chemical interactions between the quinoline ring and its environment, such as hydrogen bonding and ?-stacking, perturb the frequency of this mode in a more complicated but predictable manner. We use this vibration as a spectroscopic probe to investigate the binding interaction between quinine and DNA. We find that, when the quinoline ring is protonated, quinine weakly intercalates into DNA by forming ?-stacking interactions with the base pairs. The Raman spectra indicate that quinine can intercalate into DNA with a ratio reaching up to roughly one molecule per 25 base pairs. Our results are confirmed by MD simulations, which also show that the quinoline ring adopts a t-shaped ?-stacking geometry with the DNA base pairs, whereas the quinuclidine head group weakly interacts with the phosphate backbone in the minor groove. We expect that the spectral correlations determined here will enable future studies to probe quinine's antimalarial activities, such as disrupting hemozoin biocrystallization, which is hypothesized to be, among other things, one of its primary modes of action against Plasmodium parasites.

Dataset Information

GoLoco motif proteins binding to Galpha(i1): insights from molecular simulations.

Publications

GoLoco motif proteins binding to Galpha(i1): insights from molecular simulations.

Similar Datasets

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