title: Effects of phosphorylation on the structure and backbone dynamics of the intrinsically disordered connexin43 C-terminal domain.
abstract: Phosphorylation of the connexin43 C-terminal (Cx43CT) domain regulates gap junction intercellular communication. However, an understanding of the mechanisms by which phosphorylation exerts its effects is lacking. Here, we test the hypothesis that phosphorylation regulates Cx43 gap junction intercellular communication by mediating structural changes in the C-terminal domain. Circular dichroism and nuclear magnetic resonance were used to characterize the effects of phosphorylation on the secondary structure and backbone dynamics of soluble and membrane-tethered Cx43CT domains. Cx43CT phospho-mimetic isoforms, which have Asp substitutions at specific Ser/Tyr sites, revealed phosphorylation alters the α-helical content of the Cx43CT domain only when attached to the membrane. The changes in secondary structure are due to variations in the conformational preference and backbone flexibility of residues adjacent and distal to the site(s) of modification. In addition to the known direct effects of phosphorylation on molecular partner interactions, the data presented here suggest phosphorylation may also indirectly regulate binding affinity by altering the conformational preference of the Cx43CT domain.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA.
authors.forename: Rosslyn
authors.initials: R
authors.lastname: Grosely
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Kopanic
authors.forename: Sarah
authors.initials: S
authors.lastname: Nabors
authors.forename: Fabien
authors.initials: F
authors.lastname: Kieken
authors.forename: Gaëlle
authors.initials: G
authors.lastname: Spagnol
authors.forename: Mona
authors.initials: M
authors.lastname: Al-Mugotir
authors.forename: Sydney
authors.initials: S
authors.lastname: Zach
authors.forename: Paul L
authors.initials: PL
authors.lastname: Sorgen
mesh_terms: D002942:Circular Dichroism; D018031:Connexin 43 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D010766:Phosphorylation / Q000502:physiology; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D018031:Connexin 43; C500216:GJA1 protein, human
keywords: Circular Dichroism (CD); Gap Junctions; Nuclear Magnetic Resonance; Phosphorylation; Protein Dynamics