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Computational approaches to understanding activation of the angiotensin II type 1 receptor
Author(s) -
Anderson Shane D,
BotelloSmith Wesley M.,
Luo Yun Lyna,
Andresen Bradley T.
Publication year - 2017
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.31.1_supplement.992.15
Subject(s) - olmesartan , popc , chemistry , receptor , angiotensin ii , molecular dynamics , agonist , biophysics , inverse agonist , membrane , biochemistry , lipid bilayer , endocrinology , biology , computational chemistry , blood pressure
The angiotensin II type 1 receptor (AT 1 R) is a major player in the cardiovascular system and is involved in volume and salt homeostasis. Multiple models of the AT 1 R have been made to predict molecular function; however, the previous models were invalidated by the crystallization of the AT 1 R bound to ZD 7155 (4ZUD) as well as the inverse agonist olmesartan (4YAY). Molecular dynamics models of receptors have a benefit as they allow dynamic interrogation of structure‐activity relationships and aid in designing novel therapeutics. Therefore, the aim of this project is to generate models of the empty and active human AT 1 R to determine structural changes involved in receptor activation. To produce a model of the empty AT 1 R, olmesartan and BRIL were removed from 4YAY, and the missing loops and the amino‐terminus were added to the structure. This model was inserted into an 87% POPC and 13% cholesterol membrane and simulated using AMBER16 for 150 ns. Atomic fluctuation measurements from the 150ns simulation revealed extensive movements within the helices as well as the loops; generally, the empty AT 1 R relaxed resulting in increased distances between helixes. Residue alpha carbons were measured between 4YAY and the stable empty AT 1 R structure. There were multiple changes including mean changes at Tyr35 1.39 (1.9 Å), Arg167 ECL2 (2.1 Å), Ser189 ECL2 (3.7 Å), Val264 6.59 (4.4 Å), Gln267 6.62 (4.6 Å), Iso288 4.38 (1.9 Å), and Phe304 7.55 (4.7 Å) and Phe313 8.54 (9.2 Å). These changes are presumed to reflect the induced fit structure of olmesartan‐bound AT 1 R. A constitutively active AT 1 R (CA‐AT 1 R) was constructed from the stable empty AT 1 R by generating N111G AT 1 R followed by a 300 ns MD simulation. Major changes between the empty and CA‐AT 1 R occurred with residues Tyr35 1.39 (1.4 Å), Trp219 5.62 (2.7 Å), Leu297 7.48 (2.9 Å), and Phe313 8.54 (9.5 Å). Intramolecular alpha carbon measurements between the models resulted in displaying changes specific to olmesartan binding such as Ser189 ECL2 and Ala163 4.61 to Gln267 6.62 : 6.0 Å and 18.2 Å, respectively, for olmesartan bound compared to 10.7 Å and 14.5 Å for the empty AT 1 R and 10.4 Å and 14.6 Å for the CA‐AT 1 R. Conversely, there are changes unique to CA‐AT 1 R structure deeper into the AT 1 R such as Ser252 6.47 to Iso290 7.40 and the salt bridge between NH1 Arg126 3.50 and O − Arg234 6.29 : 8.6 Å and 10.4 Å for CA‐AT 1 R, respectively, compared to 6.7 Å and 8.6 Å for olmesartan bound and 6.7 Å and 2.7 Å for the empty AT 1 R. Future directions of this project include docking angiotensin II to the empty and CA AT 1 R as well as the biased agonist [Sar1‐Ile4‐Ile8]‐angiotensin II to the empty AT 1 R and comparing the conformational changes. Support or Funding Information This project was funded by internal WesternU funds.