title: A novel disulfide bond in the SH2 Domain of the C-terminal Src kinase controls catalytic activity.
abstract: The SH2 domain of the C-terminal Src kinase [Csk] contains a unique disulfide bond that is not present in other known SH2 domains. To investigate whether this unusual disulfide bond serves a novel function, the effects of disulfide bond formation on catalytic activity of the full-length protein and on the structure of the SH2 domain were investigated. The kinase activity of full-length Csk decreases by an order of magnitude upon formation of the disulfide bond in the distal SH2 domain. NMR spectra of the fully oxidized and fully reduced SH2 domains exhibit similar chemical shift patterns and are indicative of similar, well-defined tertiary structures. The solvent-accessible disulfide bond in the isolated SH2 domain is highly stable and far from the small lobe of the kinase domain. However, reduction of this bond results in chemical shift changes of resonances that map to a cluster of residues that extend from the disulfide bond across the molecule to a surface that is in direct contact with the small lobe of the kinase domain in the intact molecule. Normal mode analyses and molecular dynamics calculations suggest that disulfide bond formation has large effects on residues within the kinase domain, most notably within the active-site cleft. Overall, the data indicate that reversible cross-linking of two cysteine residues in the SH2 domain greatly impacts catalytic function and interdomain communication in Csk.
authors.affiliation: Department of Chemistry & Biochemistry, University of California-San Diego, La Jolla, CA 92093, USA.
authors.forename: Jamie E
authors.initials: JE
authors.lastname: Mills
authors.forename: Paul C
authors.initials: PC
authors.lastname: Whitford
authors.forename: Jennifer
authors.initials: J
authors.lastname: Shaffer
authors.forename: Jose N
authors.initials: JN
authors.lastname: Onuchic
authors.forename: Joseph A
authors.initials: JA
authors.lastname: Adams
authors.forename: Patricia A
authors.initials: PA
authors.lastname: Jennings
mesh_terms: D001665:Binding Sites; D000081247:CSK Tyrosine-Protein Kinase; D002384:Catalysis; D003545:Cysteine / Q000378:metabolism; D004220:Disulfides / Q000302:isolation & purification / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D010084:Oxidation-Reduction; D017433:Protein Structure, Secondary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry* / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013499:Surface Properties; D018909:src Homology Domains; D019061:src-Family Kinases
chemical_list: D004220:Disulfides; D011505:Protein-Tyrosine Kinases; D000081247:CSK Tyrosine-Protein Kinase; D019061:src-Family Kinases; C000631346:CSK protein, human; D003545:Cysteine