title: Minimal residues in linker domain of syntaxin 1A required for binding affinity to Ca2+/calmodulin-dependent protein kinase II.
abstract: The linker domain is important for the conformational change syntaxin 1A, which enables it to act as a SNARE for exocytosis. We found that when applied exogenously, the linker domain is a potent inhibitor of exocytosis through inhibiting interaction between autophosphorylated CaMKII and endogenous syntaxin 1A (Ohyama et al. [2002] J. Neurosci. 22:3342-3351). To identify the simplest and the most potent inhibitor for exocytosis, we further characterized the linker domain and determined the minimal number of residues required for CaMKII binding. The minimal length of the CaMKII-binding site was 145-172 residues and a loss of G172 considerably weakened affinity for CaMKII. The basic amino acid clusters, R151 and K146, were indispensable for binding, whereas R148 was not. A comparison of the CaMKII-binding in several syntaxin isoforms revealed that the substitution of S162 attenuated CaMKII-binding activity. These results suggest that S162 is an important residue as well as the basic amino acid cluster within region 145-172 of the linker domain.
authors.affiliation: Department of Orthopedics, Gunma University School of Medicine, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Nomura
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ohyama
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Komiya
authors.forename: Michihiro
authors.initials: M
authors.lastname: Igarashi
mesh_terms: D020816:Amino Acid Motifs / Q000502:physiology; D000595:Amino Acid Sequence; D000818:Animals; D000954:Antigens, Surface / Q000737:chemistry* / Q000378:metabolism*; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D017124:Conserved Sequence / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding / Q000502:physiology*; D020033:Protein Isoforms; D017434:Protein Structure, Tertiary / Q000502:physiology; D012694:Serine / Q000378:metabolism; D013379:Substrate Specificity / Q000502:physiology; D050827:Syntaxin 1
chemical_list: D000954:Antigens, Surface; D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D050827:Syntaxin 1; D012694:Serine; D017871:Calcium-Calmodulin-Dependent Protein Kinases