The covalent maleimidobenzoyl-actin-myosin head complex. Cross-linking of the 50 kDa heavy chain region to actin subdomain-2.
We have identified the region of actin involved in the covalent coupling of maleimidobenzoyl-G-actin to the central 50 kDa segment of the myosin-S-1 heavy chain by analyzing the structure of the maleimidobenzoyl-G-actin-S-1 conjugate using selective proteolytic digestions, amino acid sequence determinations and novel cross-linking reactions between S-1 and different maleimidobenzoyl-G-actin derivatives. The cross-linking is shown to occur only on the stretch of residues 48-67 in actin subdomain-2 with Lys-50, residing on the outer part of the DNase-I-binding loop, as the most likely site of cross-linking. Because the maleimidobenzoyl-F-actin-S-1 complex undergoes the same coupling process, the data provide experimental evidence in favor of the recent model of the rigor F-actin-S-1 complex suggesting a close contact between structural elements of the lower domain of the 50 kDa fragment and the top of actin subdomain-2.
Bertrand
R
R
Centre de Recherches de Biochimie Macromoléculaire du CNRS, INSERM U 249, Université de Montpellier I, France.
Derancourt
J
J
Kassab
R
R
D000199:Actins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002918:Chymotrypsin; D004591:Electrophoresis, Polyacrylamide Gel; D016650:Fluorescein-5-isothiocyanate; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009132:Muscles / Q000378:metabolism; D015879:Myosin Subfragments / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D010449:Peptide Mapping; D011485:Protein Binding; D011817:Rabbits
D000199:Actins; D015879:Myosin Subfragments; C066969:maleimidobenzoyl-G-actin; D002918:Chymotrypsin; D016650:Fluorescein-5-isothiocyanate