Identification of trapped and boundary lipid binding sites in M13 coat protein/lipid complexes by deuterium NMR spectroscopy
- Univ. of Oxford (England)
The major coat protein of M13 bacteriophage has been incorporated into bilayers of 1,2-dimyristoyl-sn-glycero-3-phosphocholine, deuterated in the trimethyl segments of the choline headgroup (DMPC-d9). Two-component deuterium and phosphorus-31 NMR spectra have been observed from bilayer complexes containing the coat protein, indicating slow exchange (on the deuterium quadrupole anisotropy and phosphorus-31 chemical shift averaging time scales) of lipid molecules of less than 10(3) Hz between two motionally distinct environments in the complexes. The fraction of the isotropic spectral component increases with increasing M13 protein concentration, and this component is attributed to lipid headgroups, which are disordered relative to their order in protein-free bilayers. The activation energy of the fast local motions of the trimethyl groups of the choline residue in the headgroup decreases from 23 kJ mol-1 in the pure lipid bilayers to 20 kJ mol-1 for the protein-associated lipid headgroups. The chemical exchange rate of lipid molecules between the two motionally distinct environments has been estimated to be 20-50 Hz by steady-state line-shape simulations of the deuterium spectra of DMPC-d9/M13 coat protein complexes using exchange-coupled modified Bloch equations. The off-rate was, as expected from one-to-one exchange, independent of the L/P ratio; tau off -1 = 0.23 kHz. It is suggested that the protein-associated lipid may be trapped between closely packed parallel aggregates of M13 coat protein and that the high local concentration of protein in a one-dimensional arrangement in lipid bilayers may be required for the fast reassembly of phage particles before release from an infected cell.
- OSTI ID:
- 6708916
- Journal Information:
- Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:16; ISSN 0006-2960; ISSN BICHA
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
BACTERIOPHAGES
CHEMICAL SHIFT
DEUTERIUM
HYDROGEN ISOTOPES
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
MAGNETIC RESONANCE
MEMBRANE PROTEINS
MICROORGANISMS
MOLECULAR STRUCTURE
NMR SPECTRA
NUCLEAR MAGNETIC RESONANCE
NUCLEI
ODD-EVEN NUCLEI
ODD-ODD NUCLEI
ORGANIC COMPOUNDS
PARASITES
PHOSPHORUS 31
PHOSPHORUS ISOTOPES
PROTEINS
RESONANCE
SPECTRA
STABLE ISOTOPES
TRACER TECHNIQUES
VIRUSES