A circular dichroic study of helical structure in flagellar dynein.
The circular dichroic spectra of outer arm dynein from sea urchin sperm flagella, of its separated alpha and beta heavy-chain complexes, and of the two major fragments produced by tryptic digestion of the beta heavy chain have been measured over the range 190-240 nm. Although the spectra show significant individuality, in all cases they qualitatively resemble those of typical globular proteins with mixed regions of alpha-helix and beta-sheet (alpha/beta-type structure) or with separate alpha-helix- and beta-sheet-rich regions (alpha+beta-type structure). Quantitative analyses of the spectra by both constrained and unconstrained least-squares curve-fitting procedures indicate that the intact dynein contains approximately 26% alpha-helix. The separated beta heavy-chain complex and its ATPase-containing amino-terminal domain (fragment A) both have spectra resembling that of intact dynein, and they appear to contain 32% and 23% alpha-helix, respectively. The carboxy-terminal domain of the beta heavy chain (fragment B) and the separated alpha heavy chain have significantly different spectra; however, they each appear to contain 26-36% alpha-helix. These data suggest that dynein does not contain an extensive alpha-helical domain, such as is found in the carboxy-terminal rod region of the other motor proteins myosin and kinesin.
Mocz
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Pacific Biomedical Research Center, University of Hawaii, Honolulu 96822.
Gibbons
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IR
D000251:Adenosine Triphosphatases; D000818:Animals; D002942:Circular Dichroism; D004398:Dyneins / Q000302:isolation & purification / Q000648:ultrastructure*; D008297:Male; D015394:Molecular Structure; D010446:Peptide Fragments / Q000302:isolation & purification; D011487:Protein Conformation; D012617:Sea Urchins; D013082:Sperm Tail / Q000032:analysis / Q000648:ultrastructure*; D013094:Spermatozoa / Q000648:ultrastructure*
D010446:Peptide Fragments; D000251:Adenosine Triphosphatases; D004398:Dyneins