title: Adenylyl Cyclase 5 Regulation by Gβγ Involves Isoform-Specific Use of Multiple Interaction Sites.
abstract: Adenylyl cyclase (AC) converts ATP into cyclic AMP (cAMP), an important second messenger in cell signaling. Heterotrimeric G proteins and other regulators are important for control of AC activity. Depending on the AC isoform, Gβγ subunits can either conditionally stimulate or inhibit cAMP synthesis. We previously showed that the Gαs-βγ heterotrimer binds to the N terminus (NT) of type 5 AC (AC5). We now show that Gβγ binds to the NT of a wide variety of AC isoforms. We hypothesized that Gβγ/AC5 interactions involving inactive heterotrimer and Gβγ stimulation of AC5 were separable events. Mutations of the Gβγ "hotspot" show that this site is necessary for AC5 stimulation but not for interactions with the first 198 aa of AC5NT, which is a G protein scaffolding site. This contrasts with AC6, where the Gβγ hotspot is required for both interactions with AC6NT and for stimulation of AC6. Additionally, the SIGK hotspot peptide disrupts Gβγ regulation of AC isoforms 1, 2, and 6, but not AC5. Gβγ also binds the C1/C2 catalytic domains of AC5 and AC6. Finally, cellular interactions with full-length AC5 depend on multiple sites on Gβγ. This suggests an isoform-specific mechanism in which bound Gβγ at the AC5NT is ideally situated for spatiotemporal control of AC5. We propose Gβγ regulation of AC involves multiple binding events, and the role of the AC NT for mechanisms of regulation by heterotrimeric G protein subunits is isoform-specific.
authors.affiliation: Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.).
authors.forename: Cameron S
authors.initials: CS
authors.lastname: Brand
authors.affiliation: Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.).
authors.forename: Rachna
authors.initials: R
authors.lastname: Sadana
authors.affiliation: Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.).
authors.forename: Sundeep
authors.initials: S
authors.lastname: Malik
authors.affiliation: Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.).
authors.forename: Alan V
authors.initials: AV
authors.lastname: Smrcka
authors.affiliation: Department of Integrative Biology and Pharmacology, University of Texas Health Science Center, Houston, Texas (C.S.B., C.W.D.); Department of Natural Sciences, University of Houston-Downtown, Houston, Texas (R.S.); and Department of Pharmacology and Physiology, University of Rochester School of Medicine, Rochester, New York (S.M., A.V.S.) Carmen.W.Dessauer@uth.tmc.edu.
authors.forename: Carmen W
authors.initials: CW
authors.lastname: Dessauer
mesh_terms: D000262:Adenylyl Cyclases / Q000502:physiology*; D001665:Binding Sites / Q000502:physiology; D044387:GTP-Binding Protein beta Subunits / Q000737:chemistry* / Q000378:metabolism*; D044388:GTP-Binding Protein gamma Subunits / Q000737:chemistry* / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D020033:Protein Isoforms / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary
chemical_list: C118981:G-protein Beta gamma; D044387:GTP-Binding Protein beta Subunits; D044388:GTP-Binding Protein gamma Subunits; D020033:Protein Isoforms; D000262:Adenylyl Cyclases; C419510:adenylyl cyclase type V