MsGC-beta3 forms active homodimers and inactive heterodimers with NO-sensitive soluble guanylyl cyclase subunits

J Exp Biol. 2003 Mar;206(Pt 6):937-47. doi: 10.1242/jeb.00160.

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.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Western
  • COS Cells
  • Catalytic Domain
  • Chromatography, Gel
  • DNA Primers / genetics
  • Dimerization
  • Guanylate Cyclase / biosynthesis*
  • Guanylate Cyclase / genetics
  • Manduca / enzymology*
  • Mutagenesis, Site-Directed / genetics
  • Point Mutation
  • Receptors, Cytoplasmic and Nuclear / biosynthesis*
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Soluble Guanylyl Cyclase
  • Transfection

Substances

  • DNA Primers
  • Receptors, Cytoplasmic and Nuclear
  • Guanylate Cyclase
  • Soluble Guanylyl Cyclase