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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

[6–10]DrmMS docked to DrmMS-R1.[6–10]RhpMS did not retain many of the DrmMS contact sites with DrmMS-R1 thus is was unlike the parent peptide, consistent with SAR data that established it was inactive in gut, but the active core in heart. Thus, taken together, these data indicated [6–10]DrmMS did activate DrmMS-R1 in the gut.
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pone.0120492.g008: [6–10]DrmMS docked to DrmMS-R1.[6–10]RhpMS did not retain many of the DrmMS contact sites with DrmMS-R1 thus is was unlike the parent peptide, consistent with SAR data that established it was inactive in gut, but the active core in heart. Thus, taken together, these data indicated [6–10]DrmMS did activate DrmMS-R1 in the gut.

Mentions: In [6–10]DrmMS, the active core in heart, but inactive in gut, docked to DrmMS-R1 (Fig. 8, Table 8), F7 maintained multiple, strong hydrophobic and aromatic contacts, extending deeper into the pocket compared to DrmMS. L8 was directed towards TM1 and TM2 and failed to make contacts with F7. V6 made hydrophobic contacts. R9 and F10 filled the pocket yet failed to retain many DrmMS-like contacts. [6–10]DrmMS docked to DrmMS-R2 was similar to DrmMS (Fig. 9, Table 9). F10 interacted with hydrophobic and aromatic residues on TM1 and TM2. V6, F7, and L8 made hydrophobic contacts to TM3, TM4, and TM5, pi-stacked with TM5, and retained N-terminal contacts. F7 and F10 maintained strong interactions within separate networks in the pocket, much like DrmMS. The similar contacts suggested a role for DrmMS-R2 signaling in heart. In [7–10]DrmMS, inactive in heart, docked to DrmMS-R2 (Fig. 10, Table 10) the analog location was similar to [6–10]DrmMS and F7 contacts were identical. However, the loss of V6 changed the backbone conformation and altered the L8 and R9 side chain orientations and contacts. The largest difference was the rotation of F4, it contacted hydrophobic residues between TM2 and TM3, losing contacts to TM1 and TM2. [7–10]DrmMS resulted in weaker ligand-receptor contacts compared to [6–10]DrmMS, consistent with inactivity versus activity of these analogs in heart.


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)

[6–10]DrmMS docked to DrmMS-R1.[6–10]RhpMS did not retain many of the DrmMS contact sites with DrmMS-R1 thus is was unlike the parent peptide, consistent with SAR data that established it was inactive in gut, but the active core in heart. Thus, taken together, these data indicated [6–10]DrmMS did activate DrmMS-R1 in the gut.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0120492.g008: [6–10]DrmMS docked to DrmMS-R1.[6–10]RhpMS did not retain many of the DrmMS contact sites with DrmMS-R1 thus is was unlike the parent peptide, consistent with SAR data that established it was inactive in gut, but the active core in heart. Thus, taken together, these data indicated [6–10]DrmMS did activate DrmMS-R1 in the gut.
Mentions: In [6–10]DrmMS, the active core in heart, but inactive in gut, docked to DrmMS-R1 (Fig. 8, Table 8), F7 maintained multiple, strong hydrophobic and aromatic contacts, extending deeper into the pocket compared to DrmMS. L8 was directed towards TM1 and TM2 and failed to make contacts with F7. V6 made hydrophobic contacts. R9 and F10 filled the pocket yet failed to retain many DrmMS-like contacts. [6–10]DrmMS docked to DrmMS-R2 was similar to DrmMS (Fig. 9, Table 9). F10 interacted with hydrophobic and aromatic residues on TM1 and TM2. V6, F7, and L8 made hydrophobic contacts to TM3, TM4, and TM5, pi-stacked with TM5, and retained N-terminal contacts. F7 and F10 maintained strong interactions within separate networks in the pocket, much like DrmMS. The similar contacts suggested a role for DrmMS-R2 signaling in heart. In [7–10]DrmMS, inactive in heart, docked to DrmMS-R2 (Fig. 10, Table 10) the analog location was similar to [6–10]DrmMS and F7 contacts were identical. However, the loss of V6 changed the backbone conformation and altered the L8 and R9 side chain orientations and contacts. The largest difference was the rotation of F4, it contacted hydrophobic residues between TM2 and TM3, losing contacts to TM1 and TM2. [7–10]DrmMS resulted in weaker ligand-receptor contacts compared to [6–10]DrmMS, consistent with inactivity versus activity of these analogs in heart.

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