Predictably Convergent Evolution of Sodium Channels in the Arms Race between Predators and Prey

2015 ◽  
Vol 86 (1) ◽  
pp. 48-57 ◽  
Author(s):  
Edmund D. Brodie III ◽  
Edmund D. Brodie Jr.
Keyword(s):  
Amino Acid ◽  
Sodium Channels ◽  
Structural Changes ◽  
Molecular Mechanisms ◽  
Adaptive Landscape ◽  
Amino Acid Residues ◽  
Common Amino Acid ◽  
Voltage Gated Sodium Channels ◽  
Trade Offs ◽  
Puffer Fish

Evolution typically arrives at convergent phenotypic solutions to common challenges of natural selection. However, diverse molecular and physiological mechanisms may generate phenotypes that appear similar at the organismal level. How predictable are the molecular mechanisms of adaptation that underlie adaptive convergence? Interactions between toxic prey and their predators provide an excellent avenue to investigate the question of predictability because both taxa must adapt to the presence of defensive poisons. The evolution of resistance to tetrodotoxin (TTX), which binds to and blocks voltage-gated sodium channels (NaV1) in nerves and muscle, has been remarkably parallel across deep phylogenetic divides. In both predators and prey, representing three major vertebrate groups, TTX resistance has arisen through structural changes in NaV1 proteins. Fish, amphibians and reptiles, though they differ in the total number of NaV1 paralogs in their genomes, have each evolved common amino acid substitutions in the orthologous skeletal muscle NaV1.4. Many of these substitutions involve not only the same positions in the protein, but also the identical amino acid residues. Similarly, predictable convergence is observed across the family of sodium channel genes expressed in different tissues in puffer fish and in garter snakes. Trade-offs between the fundamental role of NaV1 proteins in selective permeability of Na+ and their ability to resist binding by TTX generate a highly constrained adaptive landscape at the level of the protein.

Expression and Mutagenesis of the Sea Anemone Toxin Av2 Reveals Key Amino Acid Residues Important for Activity on Voltage-Gated Sodium Channels†

Biochemistry ◽  
2006 ◽  
Vol 45 (29) ◽  
pp. 8864-8873 ◽  
Author(s):  
Yehu Moran ◽  
Lior Cohen ◽  
Roy Kahn ◽  
Izhar Karbat ◽  
Dalia Gordon ◽  
...  
Keyword(s):  
Amino Acid ◽  
Sodium Channels ◽  
Sea Anemone ◽  
Amino Acid Residues ◽  
Voltage Gated ◽  
Voltage Gated Sodium Channels ◽  
Sea Anemone Toxin

scholarly journals Deletion of the Actin-Associated Tropomyosin Tpm3 Leads to Reduced Cell Complexity in Cultured Hippocampal Neurons—New Insights into the Role of the C-Terminal Region of Tpm3.1

Cells ◽  
2021 ◽  
Vol 10 (3) ◽  
pp. 715
Author(s):  
Tamara Tomanić ◽  
Claire Martin ◽  
Holly Stefen ◽  
Esmeralda Parić ◽  
Peter Gunning ◽  
...  
Keyword(s):  
Amino Acid ◽  
Hippocampal Neurons ◽  
Molecular Mechanisms ◽  
Growth Cones ◽  
Amino Acid Residues ◽  
Terminal Amino Acid ◽  
C Terminus ◽  
Primary Mouse ◽  
Terminal Amino

Tropomyosins (Tpms) have been described as master regulators of actin, with Tpm3 products shown to be involved in early developmental processes, and the Tpm3 isoform Tpm3.1 controlling changes in the size of neuronal growth cones and neurite growth. Here, we used primary mouse hippocampal neurons of C57/Bl6 wild type and Bl6Tpm3flox transgenic mice to carry out morphometric analyses in response to the absence of Tpm3 products, as well as to investigate the effect of C-terminal truncation on the ability of Tpm3.1 to modulate neuronal morphogenesis. We found that the knock-out of Tpm3 leads to decreased neurite length and complexity, and that the deletion of two amino acid residues at the C-terminus of Tpm3.1 leads to more detrimental changes in neurite morphology than the deletion of six amino acid residues. We also found that Tpm3.1 that lacks the 6 C-terminal amino acid residues does not associate with stress fibres, does not segregate to the tips of neurites, and does not impact the amount of the filamentous actin pool at the axonal growth cones, as opposed to Tpm3.1, which lacks the two C-terminal amino acid residues. Our study provides further insight into the role of both Tpm3 products and the C-terminus of Tpm3.1, and it forms the basis for future studies that aim to identify the molecular mechanisms underlying Tpm3.1 targeting to different subcellular compartments.

Identification of odorant-binding protein genes inGaleruca daurica(Coleoptera: Chrysomelidae) and analysis of their expression profiles

2017 ◽  
Vol 107 (4) ◽  
pp. 550-561 ◽  
Author(s):  
L. Li ◽  
Y.-T. Zhou ◽  
Y. Tan ◽  
X.-R. Zhou ◽  
B.-P. Pang
Keyword(s):  
Amino Acid ◽  
Molecular Mechanisms ◽  
Insect Pests ◽  
Expression Profiles ◽  
Open Reading Frames ◽  
Amino Acid Residues ◽  
Expression Levels ◽  
Molecular Weights ◽  
Related Proteins ◽  
Odorant Binding

AbstractOdorant-binding proteins (OBPs) play a fundamental role in insect olfaction. In recent years,Galeruca daurica(Joannis) (Coleoptera: Chrysomelidae) has become one of the most important insect pests in the Inner Mongolian grasslands of China. This pest only feeds on the species ofAlliumplants, implying the central role of olfaction in its search for specific host plants. However, the olfaction-related proteins have not been investigated in this beetle. In this study, we identified 29 putative OBP genes, namely GdauOBP1–29, from the transcriptome database ofG. dauricaassembled in our laboratory by using RNA-Seq. All 29 genes had the full-length open reading frames except GdauOBP29, encoding proteins in length from 119 to 202 amino acids with their predicted molecular weights from 12 to 22 kDa with isoelectric points from 3.88 to 8.84. Predicted signal peptides consisting of 15–22 amino acid residues were found in all except GdauOBP6, GdauOBP13 and GdauOBP29. The amino acid sequence identity between the 29 OBPs ranged 8.33–71.83%. GdauOBP1–12 belongs to the Classic OBPs, while the others belong with the Minus-C OBPs. Phylogenetic analysis indicated that GdauOBPs are the closest to CbowOBPs fromColaphellus bowringi. RT-PCR and qRT-PCR analyses showed that all GdauOBPs were expressed in adult antennae, 11 of which with significant differences in their expression levels between males and females. Most GdauOBPs were also expressed in adult heads (without antennae), thoraxes, abdomens, legs and wings. Moreover, the expression levels of the GdauOBPs varied during the different development stages ofG. dauricawith most GdauOBPs expressed highly in the adult antennae but scarcely in eggs and pupae. These results provide insights for further research on the molecular mechanisms of chemical communications inG. daurica.

Roles of Basic Amino Acid Residues in the Activity of μ -Conotoxin GIIIA and GIIIB, Peptide Blockers of Muscle Sodium Channels

2014 ◽  
Vol 85 (4) ◽  
pp. 488-493 ◽  
Author(s):  
Kazuki Sato ◽  
Yoko Yamaguchi ◽  
Yukisato Ishida ◽  
Yasushi Ohizumi
Keyword(s):  
Amino Acid ◽  
Sodium Channels ◽  
Basic Amino Acid ◽  
Amino Acid Residues

scholarly journals Volatile anesthetics inhibit sodium channels without altering bulk lipid bilayer properties

2014 ◽  
Vol 144 (6) ◽  
pp. 545-560 ◽  
Author(s):  
Karl F. Herold ◽  
R. Lea Sanford ◽  
William Lee ◽  
Margaret F. Schultz ◽  
Helgi I. Ingólfsson ◽  
...  
Keyword(s):  
Ion Channel ◽  
Lipid Bilayer ◽  
Sodium Channels ◽  
Molecular Mechanisms ◽  
Volatile Anesthetics ◽  
Specific Protein ◽  
Functional Assay ◽  
General Anesthetics ◽  
Voltage Gated Sodium Channels ◽  
Clinical Anesthesia

Although general anesthetics are clinically important and widely used, their molecular mechanisms of action remain poorly understood. Volatile anesthetics such as isoflurane (ISO) are thought to alter neuronal function by depressing excitatory and facilitating inhibitory neurotransmission through direct interactions with specific protein targets, including voltage-gated sodium channels (Nav). Many anesthetics alter lipid bilayer properties, suggesting that ion channel function might also be altered indirectly through effects on the lipid bilayer. We compared the effects of ISO and of a series of fluorobenzene (FB) model volatile anesthetics on Nav function and lipid bilayer properties. We examined the effects of these agents on Nav in neuronal cells using whole-cell electrophysiology, and on lipid bilayer properties using a gramicidin-based fluorescence assay, which is a functional assay for detecting changes in lipid bilayer properties sensed by a bilayer-spanning ion channel. At clinically relevant concentrations (defined by the minimum alveolar concentration), both the FBs and ISO produced prepulse-dependent inhibition of Nav and shifted the voltage dependence of inactivation toward more hyperpolarized potentials without affecting lipid bilayer properties, as sensed by gramicidin channels. Only at supra-anesthetic (toxic) concentrations did ISO alter lipid bilayer properties. These results suggest that clinically relevant concentrations of volatile anesthetics alter Nav function through direct interactions with the channel protein with little, if any, contribution from changes in bulk lipid bilayer properties. Our findings further suggest that changes in lipid bilayer properties are not involved in clinical anesthesia.

Sign in / Sign up

Export Citation Format

Share Document