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Cardiac contractility structure-activity relationship and ligand-receptor interactions; the discovery of unique and novel molecular switches in myosuppressin signaling.

Leander M, Bass C, Marchetti K, Maynard BF, Wulff JP, Ons S, Nichols R - PLoS ONE (2015)

Bottom Line: RhpMS and DrmMS decreased R. prolixus cardiac contractility dose dependently with EC50 values of 140 nM and 50 nM.Based on ligand-receptor contacts, we designed RhpMS analogs believed to be an active core and antagonist; testing on heart confirmed these predictions.The active core docking mimicked RhpMS, however, the antagonist did not.

View Article: PubMed Central - PubMed

Affiliation: Undergraduate Biochemistry Program, Chemistry Department, University of Michigan, Ann Arbor, Michigan, United States of America, 48109; Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 48109.

ABSTRACT
Peptidergic signaling regulates cardiac contractility; thus, identifying molecular switches, ligand-receptor contacts, and antagonists aids in exploring the underlying mechanisms to influence health. Myosuppressin (MS), a decapeptide, diminishes cardiac contractility and gut motility. Myosuppressin binds to G protein-coupled receptor (GPCR) proteins. Two Drosophila melanogaster myosuppressin receptors (DrmMS-Rs) exist; however, no mechanism underlying MS-R activation is reported. We predicted DrmMS-Rs contained molecular switches that resembled those of Rhodopsin. Additionally, we believed DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 interactions would reflect our structure-activity relationship (SAR) data. We hypothesized agonist- and antagonist-receptor contacts would differ from one another depending on activity. Lastly, we expected our study to apply to other species; we tested this hypothesis in Rhodnius prolixus, the Chagas disease vector. Searching DrmMS-Rs for molecular switches led to the discovery of a unique ionic lock and a novel 3-6 lock, as well as transmission and tyrosine toggle switches. The DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 contacts suggested tissue-specific signaling existed, which was in line with our SAR data. We identified R. prolixus (Rhp)MS-R and discovered it, too, contained the unique myosuppressin ionic lock and novel 3-6 lock found in DrmMS-Rs as well as transmission and tyrosine toggle switches. Further, these motifs were present in red flour beetle, common water flea, honey bee, domestic silkworm, and termite MS-Rs. RhpMS and DrmMS decreased R. prolixus cardiac contractility dose dependently with EC50 values of 140 nM and 50 nM. Based on ligand-receptor contacts, we designed RhpMS analogs believed to be an active core and antagonist; testing on heart confirmed these predictions. The active core docking mimicked RhpMS, however, the antagonist did not. Together, these data were consistent with the unique ionic lock, novel 3-6 lock, transmission switch, and tyrosine toggle switch being involved in mechanisms underlying TM movement and MS-R activation, and the ability of MS agonists and antagonists to influence physiology.

No MeSH data available.


Related in: MedlinePlus

DrmMS docked to DrmMS-R2.The DrmMS ligand is shown docked to DrmMS-R2; see Fig. 4 for notation of the amino acids. Residues in the C-terminal region, particularly F7 and F10, made strong hydrophobic and aromatic contacts. D2 and R9 formed an ionic network near TM6 and the N terminus filled the remainder of the binding pocket.
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pone.0120492.g005: DrmMS docked to DrmMS-R2.The DrmMS ligand is shown docked to DrmMS-R2; see Fig. 4 for notation of the amino acids. Residues in the C-terminal region, particularly F7 and F10, made strong hydrophobic and aromatic contacts. D2 and R9 formed an ionic network near TM6 and the N terminus filled the remainder of the binding pocket.

Mentions: [6–10]DrmMS was the heart rate active core, yet [4–10]DrmMS was the gut motility active core. The alanine scans performed in heart and gut showed the residues crucial to DrmMS activity and binding are different between the two tissues; F7 and L8 were essential in gut, and F7 and F10 in heart. We believed DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 interactions would reflect our SAR data. N-terminal truncated and alanyl-substituted analogs (Table 3) were docked to the receptors; additional data are available in Supporting Information. In DrmMS docked to DrmMS-R1 (Fig. 4, Table 4), F7 made multiple, strong hydrophobic and aromatic contacts, which L8 extended by interacting with hydrophobic residues on TM1, TM2 and TM7. H5, V6, and F10 formed additional hydrophobic contacts between TM4, TM5, and TM6; H5 made extensive interactions within this region. The N-terminal residues formed weaker hydrophobic and polar interactions to TM2 and TM3. In DrmMS-R2 (Fig. 5, Table 5), F7 formed contacts between TM1 and TM2; the position of F10 on TM7 allowed for hydrophobic and aromatic interactions with ECL3. D2 and R9 interacted and formed an ionic network near TM6. D4 made extensive intramolecular interactions with the backbone to stabilize the peptide. The N terminus spanned the pocket to make hydrophobic and polar interactions with TM3, TM4, and TM5. The residues which formed strong interactions differed between the DrmMS-Rs, in particular, L8, F7, and F10 showed receptor-specific ligand binding in line with our tissue-specific SAR data.


Cardiac contractility structure-activity relationship and ligand-receptor interactions; the discovery of unique and novel molecular switches in myosuppressin signaling.

Leander M, Bass C, Marchetti K, Maynard BF, Wulff JP, Ons S, Nichols R - PLoS ONE (2015)

DrmMS docked to DrmMS-R2.The DrmMS ligand is shown docked to DrmMS-R2; see Fig. 4 for notation of the amino acids. Residues in the C-terminal region, particularly F7 and F10, made strong hydrophobic and aromatic contacts. D2 and R9 formed an ionic network near TM6 and the N terminus filled the remainder of the binding pocket.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4368603&req=5

pone.0120492.g005: DrmMS docked to DrmMS-R2.The DrmMS ligand is shown docked to DrmMS-R2; see Fig. 4 for notation of the amino acids. Residues in the C-terminal region, particularly F7 and F10, made strong hydrophobic and aromatic contacts. D2 and R9 formed an ionic network near TM6 and the N terminus filled the remainder of the binding pocket.
Mentions: [6–10]DrmMS was the heart rate active core, yet [4–10]DrmMS was the gut motility active core. The alanine scans performed in heart and gut showed the residues crucial to DrmMS activity and binding are different between the two tissues; F7 and L8 were essential in gut, and F7 and F10 in heart. We believed DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 interactions would reflect our SAR data. N-terminal truncated and alanyl-substituted analogs (Table 3) were docked to the receptors; additional data are available in Supporting Information. In DrmMS docked to DrmMS-R1 (Fig. 4, Table 4), F7 made multiple, strong hydrophobic and aromatic contacts, which L8 extended by interacting with hydrophobic residues on TM1, TM2 and TM7. H5, V6, and F10 formed additional hydrophobic contacts between TM4, TM5, and TM6; H5 made extensive interactions within this region. The N-terminal residues formed weaker hydrophobic and polar interactions to TM2 and TM3. In DrmMS-R2 (Fig. 5, Table 5), F7 formed contacts between TM1 and TM2; the position of F10 on TM7 allowed for hydrophobic and aromatic interactions with ECL3. D2 and R9 interacted and formed an ionic network near TM6. D4 made extensive intramolecular interactions with the backbone to stabilize the peptide. The N terminus spanned the pocket to make hydrophobic and polar interactions with TM3, TM4, and TM5. The residues which formed strong interactions differed between the DrmMS-Rs, in particular, L8, F7, and F10 showed receptor-specific ligand binding in line with our tissue-specific SAR data.

Bottom Line: RhpMS and DrmMS decreased R. prolixus cardiac contractility dose dependently with EC50 values of 140 nM and 50 nM.Based on ligand-receptor contacts, we designed RhpMS analogs believed to be an active core and antagonist; testing on heart confirmed these predictions.The active core docking mimicked RhpMS, however, the antagonist did not.

View Article: PubMed Central - PubMed

Affiliation: Undergraduate Biochemistry Program, Chemistry Department, University of Michigan, Ann Arbor, Michigan, United States of America, 48109; Biological Chemistry Department, University of Michigan Medical School, Ann Arbor, Michigan, United States of America, 48109.

ABSTRACT
Peptidergic signaling regulates cardiac contractility; thus, identifying molecular switches, ligand-receptor contacts, and antagonists aids in exploring the underlying mechanisms to influence health. Myosuppressin (MS), a decapeptide, diminishes cardiac contractility and gut motility. Myosuppressin binds to G protein-coupled receptor (GPCR) proteins. Two Drosophila melanogaster myosuppressin receptors (DrmMS-Rs) exist; however, no mechanism underlying MS-R activation is reported. We predicted DrmMS-Rs contained molecular switches that resembled those of Rhodopsin. Additionally, we believed DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 interactions would reflect our structure-activity relationship (SAR) data. We hypothesized agonist- and antagonist-receptor contacts would differ from one another depending on activity. Lastly, we expected our study to apply to other species; we tested this hypothesis in Rhodnius prolixus, the Chagas disease vector. Searching DrmMS-Rs for molecular switches led to the discovery of a unique ionic lock and a novel 3-6 lock, as well as transmission and tyrosine toggle switches. The DrmMS-DrmMS-R1 and DrmMS-DrmMS-R2 contacts suggested tissue-specific signaling existed, which was in line with our SAR data. We identified R. prolixus (Rhp)MS-R and discovered it, too, contained the unique myosuppressin ionic lock and novel 3-6 lock found in DrmMS-Rs as well as transmission and tyrosine toggle switches. Further, these motifs were present in red flour beetle, common water flea, honey bee, domestic silkworm, and termite MS-Rs. RhpMS and DrmMS decreased R. prolixus cardiac contractility dose dependently with EC50 values of 140 nM and 50 nM. Based on ligand-receptor contacts, we designed RhpMS analogs believed to be an active core and antagonist; testing on heart confirmed these predictions. The active core docking mimicked RhpMS, however, the antagonist did not. Together, these data were consistent with the unique ionic lock, novel 3-6 lock, transmission switch, and tyrosine toggle switch being involved in mechanisms underlying TM movement and MS-R activation, and the ability of MS agonists and antagonists to influence physiology.

No MeSH data available.


Related in: MedlinePlus