Structural changes in the carboxyl terminus of the gap junction protein connexin 40 caused by the interaction with c-Src and zonula occludens-1.
c-Src can disrupt the connexin 43 (Cx43) and zonula occludens-1 (ZO-1) interaction, leading to down-regulation of gap junction intercellular communication. Previously, the authors characterized the interaction of domains from these proteins with the carboxyl terminus of Cx43 (Cx43CT) and found that binding of the c-Src SH3 domain to Cx43CT disrupted the Cx43CT/ZO-1 PDZ-2 domain complex. Because Cx43 and Cx40 form heteromeric connexons and display similar mechanisms of pH regulation, the authors addressed whether Cx40CT interacts with these domains in a similar manner as Cx43CT. Nuclear magnetic resonance (NMR) data indicate that Cx40CT is an intrinsically disordered protein. NMR titrations determined that PDZ-2 affected the last 28 Cx40CT residues and SH3 shifted numerous amino-terminal Cx40CT residues. Finally, the Cx40CT/PDZ-2 complex was unaffected by SH3 and both domains interacted simultaneously with Cx40CT. This result differs from when the same experiment was performed with Cx43CT, suggesting different mechanisms of regulation exist between connexin isoforms, even when involving the same molecular partners.
Bouvier
Denis
D
Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska 68198, USA.
Kieken
Fabien
F
Kellezi
Admir
A
Sorgen
Paul L
PL
D000595:Amino Acid Sequence; D017630:Connexins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins / Q000378:metabolism*; D008969:Molecular Sequence Data; D010750:Phosphoproteins / Q000378:metabolism*; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000378:metabolism*; D019108:Tight Junctions / Q000378:metabolism; D062826:Zonula Occludens-1 Protein; D000097003:Gap Junction alpha-5 Protein
D017630:Connexins; D008565:Membrane Proteins; D010750:Phosphoproteins; D016392:Proto-Oncogene Proteins pp60(c-src); D062826:Zonula Occludens-1 Protein; D000097003:Gap Junction alpha-5 Protein