Solution structure of the calponin CH domain and fitting to the 3D-helical reconstruction of F-actin:calponin.
Calponin is involved in the regulation of contractility and organization of the actin cytoskeleton in smooth muscle cells. It is the archetypal member of the calponin homology (CH) domain family of actin binding proteins that includes cytoskeletal linkers such as alpha-actinin, spectrin, and dystrophin, and regulatory proteins including VAV, IQGAP, and calponin. We have determined the first structure of a CH domain from a single CH domain-containing protein, that of calponin, and have fitted the NMR-derived coordinates to the 3D-helical reconstruction of the F-actin:calponin complex using cryo-electron microscopy. The tertiary fold of this single CH domain is typical of, yet significantly different from, those of the CH domains that occur in tandem pairs to form high-affinity ABDs in other proteins. We thus provide a structural insight into the mode of interaction between F-actin and CH domain-containing proteins.
Bramham
Janice
J
Department of Biochemistry, University of Leicester, Adrian Building, University Road, Leicester LE1 7RH, United Kingdom. jb139@le.ac.uk
Hodgkinson
Julie L
JL
Smith
Brian O
BO
Uhrín
Dusan
D
Barlow
Paul N
PN
Winder
Steven J
SJ
D000199:Actins / Q000737:chemistry* / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D002135:Calcium-Binding Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D002645:Chickens; D046911:Macromolecular Substances; D009682:Magnetic Resonance Spectroscopy; D008840:Microfilament Proteins; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D011485:Protein Binding; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D012996:Solutions; D000096985:Calponins
D000199:Actins; D002135:Calcium-Binding Proteins; D046911:Macromolecular Substances; D008840:Microfilament Proteins; D012996:Solutions; D000096985:Calponins