MgADP-induced changes in the structure of myosin S1 near the ATPase-related thiol SH1 probed by cross-linking

Journal Article · Tue Mar 27 04:00:00 EST 1990 · Biochemistry; (USA)

DOI:https://doi.org/10.1021/bi00464a017· OSTI ID:6325420

Rajasekharan, K N; Mayadevi, M; Agarwal, R; Burke, M ^[1]

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1. Case Western Reserve Univ., Cleveland, OH (USA)

The structural consequence of MgADP binding at the vicinity of the ATPase-related thiol SH1 (Cys-707) have been examined by subjecting myosin subfragment 1, premodified at SH2 (Cys-697) with N-ethylmaleimide (NEM), to reaction with the bifunctional reagent p-phenylenedimaleimide (pPDM) in the presence and absence of MgADP. By monitoring the changes in the Ca{sup 2+}-ATPase activity as a function of reaction time, it appears that the reagent rapidly modifies SH1 irrespective of whether MgADP is present or not. In the absence of nucleotide, only extremely low levels of cross-linking to the 50-kDa middle segment of S1 can be detected, while in the presence of MgADP substantial cross-linking to this segment is observed. A similar cross-link is also formed if MgADP is added subsequent to the reaction of the SH2-NEM-premodified S1 with pPDM in the absence of nucleotide. Isolation of the labeled tryptic peptide from the cross-linked adduct formed with ({sup 14}C)pPDM, and subsequent partial sequence analyses, indicates that the cross-link is made from SH1 to Cys-522. Moreover, it appears that this cross-link results in the trapping of MgADP in this S1 species. These data suggest that the binding of MgADP results in a change in the structure of S1 in the vicinity of the SH1 thiol relative to the 50-kDa domain which enables Cys-522 to adopt the appropriate configuration to enable it to be cross-linked to SH1 by pPDM.

• OSTI ID: 6325420
• Journal Information: Biochemistry; (USA), Journal Name: Biochemistry; (USA) Vol. 29:12; ISSN 0006-2960; ISSN BICHA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ACID ANHYDRASES
ADP
ALKALINE EARTH METAL COMPOUNDS
ANTIMITOTIC DRUGS
ATP-ASE
BIOCHEMISTRY
CARBON 14 COMPOUNDS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
CHEMISTRY
CROSS-LINKING
DRUGS
ENZYME ACTIVITY
ENZYMES
GLOBULINS
HYDROLASES
IMIDES
IONS
LABELLED COMPOUNDS
MAGNESIUM COMPOUNDS
MOLECULAR STRUCTURE
MUSCLES
MYOSIN
NEM
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PHOSPHOHYDROLASES
PHYSIOLOGY
POLYMERIZATION
PROTEINS
RADIOSENSITIZERS
THIOLS