Solution structure of a chemosensory protein from the moth Mamestra brassicae.
Chemosensory proteins (CSPs) are believed to be involved in chemical communication and perception. A number of such proteins, of molecular mass approximately 13 kDa, have been isolated from different sensory organs of a wide range of insect species. Several CSPs have been identified in the antennae and proboscis of the moth Mamestra brassicae. CSPMbraA6, a 112-amino-acid antennal protein, has been expressed in a soluble form in large quantities in the Escherichi coli periplasm. NMR structure determination of CSPMbraA6 has been performed with 1H- and 15N-labelled samples. The calculated structures present an average root mean square deviation about the mean structure of 0.63 A for backbone atoms and 1.27 A for all non-hydrogen atoms except the 12 N-terminal residues. The protein is well folded from residue 12 to residue 110, and consists of a non-bundle alpha-helical structure with six helices connected by alpha alpha loops. It has a globular shape, with overall dimensions of 32 A x 28 A x 24 A. A channel is visible in the hydrophobic core, with dimensions of 3 A x 9 A x 21 A. In some of the 20 solution structures calculated, this channel is closed either by Trp-94 at one end or by Tyr-26 at the other end; in some other solutions, this channel is closed at both ends. Binding experiments with 12-bromododecanol indicate that the CSPMbraA6 structure is modified upon ligand binding.
Mosbah
Amor
A
AFMB, UMR 6098-CNRS and Universités Aix-Marseille I & II, 31 Chemin J. Aiguier, 13402 Marseille Cedex 20, France.
Campanacci
Valérie
V
Lartigue
Audrey
A
Tegoni
Mariella
M
Cambillau
Christian
C
Darbon
Hervé
H
D000818:Animals; D019476:Insect Proteins / Q000737:chemistry*; D008958:Models, Molecular; D009036:Moths; D019906:Nuclear Magnetic Resonance, Biomolecular; D011487:Protein Conformation
D019476:Insect Proteins