title: MsGC-beta3 forms active homodimers and inactive heterodimers with NO-sensitive soluble guanylyl cyclase subunits.
abstract: Soluble guanylyl cyclases are typically obligate heterodimers, composed of a single alpha and a single beta subunit. MsGC-beta3, identified in the tobacco hornworm Manduca sexta, was the first example of a soluble guanylyl cyclase that exhibited enzyme activity without the need for coexpression with additional subunits. Subsequent studies have revealed that the mammalian beta2 subunit also shares this property. Using a combination of gel filtration chromatography, coprecipitation and site-directed mutagenesis we show that, as predicted, MsGC-beta3 forms active homodimers. We also demonstrate that MsGC-beta3 is capable of forming heterodimers with the nitric oxide (NO)-sensitive guanylyl cyclase subunits MsGC-alpha1 and MsGC-beta1. These heterodimers, however, show no enzyme activity and, like mammalian beta2 subunits, act in a dominant negative manner when combined with the NO-sensitive subunits to disrupt their activation by NO. In addition, we show that the unique C-terminal domain of MsGC-beta3 is not necessary for enzyme activity and might act as an auto-inhibitory domain.
authors.affiliation: Department of Biological Structure and Function, Oregon Health and Science University, Portland, Oregon, USA. mortonda@ohsu.edu
authors.forename: David B
authors.initials: DB
authors.lastname: Morton
authors.forename: Esther J
authors.initials: EJ
authors.lastname: Anderson
mesh_terms: D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D020134:Catalytic Domain; D002850:Chromatography, Gel; D017931:DNA Primers / Q000235:genetics; D019281:Dimerization; D006162:Guanylate Cyclase / Q000096:biosynthesis* / Q000235:genetics; D018402:Manduca / Q000201:enzymology*; D016297:Mutagenesis, Site-Directed / Q000235:genetics; D017354:Point Mutation; D018160:Receptors, Cytoplasmic and Nuclear / Q000096:biosynthesis* / Q000235:genetics; D000071756:Soluble Guanylyl Cyclase; D014162:Transfection
chemical_list: D017931:DNA Primers; D018160:Receptors, Cytoplasmic and Nuclear; D006162:Guanylate Cyclase; D000071756:Soluble Guanylyl Cyclase