Disulfide structure of the pheromone binding protein from the silkworm moth, <i>Bombyx mori</i>

Leal, Walter S.; Nikonova, Larisa; Peng, Guihong

doi:10.1016/s0014-5793(99)01683-x

Cited by 225 publications

(165 citation statements)

References 36 publications

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“…5, which is published as supporting information on the PNAS web site), which is involved in the formation of the C-terminal ␣-helix (MDVAVGEILAE) (18). The molecular mass of BmorPBP⌬P129-V142 obtained by LC-ESI͞MS (observed, 14,466 Da; calculated, 14,472 Da) indicated that all Cys residues were linked to form three disulfide bridges, as in the native conformation (18)(19)(20)(21)(22). CD data (see Fig.…”

Section: Resultsmentioning

confidence: 98%

Kinetics and molecular properties of pheromone binding and release

Leal

Chen

Ishida

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

164

139

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Transient kinetic studies have shown that the uptake of the pheromone (bombykol) of the silkworm moth (Bombyx mori), by its pheromone-binding protein (PBP) BmorPBP, proceeds with an ''on'' rate of 0.068 ؎ 0.01 M ؊1 ⅐s ؊1 . With the high concentration of PBP in the sensillar lymph (10 mM), the half-life for the uptake of pheromone in vivo is Ϸ1 ms. A pH-dependent conformational change (BmorPBP B 3 BmorPBP A ), associated with the release of pheromone, is a first-order reaction (k ‫؍‬ 74.1 ؎ 0.32 s ؊1 ; t1/2, 9.3 ms). Under physiological conditions, both reactions proceed with half-life times on the order of milliseconds, as is required for odorant-oriented navigation in insects. Molecular interactions of bombykol with both native and mutated PBPs were analyzed by a novel binding assay. A recombinant protein with the native conformation (BmorPBP) showed high binding affinity (K D ‫؍‬ 105 nM) at pH 7 but low affinity (K D ‫؍‬ 1,600 nM) at pH 5, when tested at both low and high KCl concentrations. A protein with a C-terminal segment deleted (BmorPBP⌬P129-V142) was found to bind bombykol at pH 7 and at pH 5 with the same affinity as the native protein at pH 7, indicating that the C-terminal segment is essential for preventing binding at low pH. Binding studies with three mutated proteins (BmorPBPW37F, BmorPBPW127F, and BmorPBPW37A) showed that replacing Trp-37 (with Phe or Ala) or Trp-127 (with Phe) did not affect the binding affinity to bombykol. Fluorescence studies shed light on the contributions of Trp-37 and Trp-127 emissions to the overall fluorescence.Bombyx mori pheromone-binding protein ͉ bombykol ͉ effect of C terminus on pheromone release ͉ fast uptake of pheromone and delivery ͉ mutated pheromone-binding proteins F or many insects, small-molecule signals communicate the availability of food, the presence of friends and foes, and the readiness to mate. In general, mate-finding is an essential prerequisite for exploring insects' enormous reproductive potential and, consequently, leads to their domination of the terrestrial world. To advertise their readiness to mate, female moths, for example, produce and release sex pheromones. Only minute amounts are released, so as to avoid chemical conspicuousness. Once released, the chemical signals are diluted in the environment and mixed with a myriad of physiologically irrelevant compounds, including pheromones from other species. Even though each species communicates with a specific pheromonic language, males can detect the low-level signals from conspecific females because of a highly developed olfactory system. To find females and successfully reproduce, males may have to make long-distance, odorant-oriented flights. Navigation requires a highly selective, sensitive, and dynamic sensory system for the detection of pheromones. Given the structure of pheromone plumes (1), insects have only a few milliseconds to reset their detectors while flying in the clean air spaces between pockets of chemical signals.Pheromones are largely hydrophobic compounds, whereas pheromo...

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Section: Resultsmentioning

confidence: 98%

Kinetics and molecular properties of pheromone binding and release

Leal

Chen

Ishida

et al. 2005

Proc. Natl. Acad. Sci. U.S.A.

164

139

View full text Add to dashboard Cite

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“…OBPs are synthesised in the accessory cells surrounding neurons and are subsequently secreted into the hydrophilic extracellular space. These proteins are characterised by a specific domain that comprises six a-helices joined by three disulphide bonds (Leal et al, 1999;Scaloni et al, 1999). Although the specific physiological roles of OBPs are not well established, it is believed that they act as molecular carriers that transport and deliver odorants to chemor- …”

Section: Insect Chemosensory Gene Familiesmentioning

confidence: 99%

“…CSPs are more conserved, with a specific motif of four cysteines that form two disulphide bridges between neighbouring residues. This arrangement differs from that of OBPs, in which disulphide bridges are inter-helical and make two small loops to form a more rigid structure Leal et al, 1999;Scaloni et al, 1999). However, some CSPs can be identified by Hidden Markov Model (HMM)-based searches using information from the OBP sequence alignment as a statistical descriptor.…”

Section: Insect Chemosensory Gene Family Evolutionmentioning

confidence: 99%

Molecular evolution of the major chemosensory gene families in insects

2009

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Chemoreception is a crucial biological process that is essential for the survival of animals. In insects, olfaction allows the organism to recognise volatile cues that allow the detection of food, predators and mates, whereas the sense of taste commonly allows the discrimination of soluble stimulants that elicit feeding behaviours and can also initiate innate sexual and reproductive responses. The most important proteins involved in the recognition of chemical cues comprise moderately sized multigene families. These families include odorant-binding proteins (OBPs) and chemosensory proteins (CSPs), which are involved in peripheral olfactory processing, and the chemoreceptor superfamily formed by the olfactory receptor (OR) and gustatory receptor (GR) families. Here, we review some recent evolutionary genomic studies of chemosensory gene families using the data from fully sequenced insect genomes, especially from the 12 newly available Drosophila genomes. Overall, the results clearly support the birth-and-death model as the major mechanism of evolution in these gene families. Namely, new members arise by tandem gene duplication, progressively diverge in sequence and function, and can eventually be lost from the genome by a deletion or pseudogenisation event. Adaptive changes fostered by environmental shifts are also observed in the evolution of chemosensory families in insects and likely involve reproductive, ecological or behavioural traits. Consequently, the current size of these gene families is mainly a result of random gene gain and loss events. This dynamic process may represent a major source of genetic variation, providing opportunities for FUTURE specific adaptations.

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“…The first study concluded that the PBPs could exist in alternate redox states (24). PBPs have six highly conserved cysteine residues (25)(26)(27), which form three disulfide bridges (28,29). In a model resulting from the first study, the lower affinity reduced form releases or presents the pheromone and shifts to a higher affinity oxidized form upon interaction with the dendritic membrane (20).…”

mentioning

confidence: 99%

Olfaction in the Gypsy Moth, Lymantria dispar

Kowcun

Honson

Plettner

2001

Journal of Biological Chemistry

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The pheromone-binding proteins (PBPs) are 16-kDa abundant proteins in specialized olfactory hairs in insects. The mechanism by which the PBPs remove the pheromone from the inner surface of sensory hairs and deliver it to the sensory cell remains unclear. Existing qualitative models postulate that pheromone is released near the dendrite by a decrease in pH or by a reduced form of the PBP. This study focuses on the two PBPs from the gypsy moth and the enantiomers of the pheromone cis-2-methyl-7,8-epoxyoctadecane. The pH dependence of pheromone binding has revealed three ionizations that are important. The type of ligand influences two of these ionizations. We propose that the (؊)-enantiomer of the pheromone interacts with one of the ionizable residues on the protein while the (؉)-enantiomer does not. Simultaneous variation of pH and KCl concentration in the physiological range or reduction of disulfide bridges does not change the affinity of PBP for pheromone. We propose a revised model of pheromone transport from the inner surface of the sensory hair to the sensory neuron.

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Disulfide structure of the pheromone binding protein from the silkworm moth, Bombyx mori

Cited by 225 publications

References 36 publications

Kinetics and molecular properties of pheromone binding and release

Kinetics and molecular properties of pheromone binding and release

Molecular evolution of the major chemosensory gene families in insects

Olfaction in the Gypsy Moth, Lymantria dispar

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