The coiled-coil helix in the neck of kinesin.
Kinesin is a microtubule-dependent motor protein. We have recently determined the X-ray structure of monomeric and dimeric kinesin from rat brain. The dimer consists of two motor domains, held together by their alpha-helical neck domains forming a coiled coil. Here we analyze the nature of the interactions in the neck domain (residues 339-370). Overall, the neck helix shows a heptad repeat (abcdefg)n typical of coiled coils, with mostly nonpolar residues in positions a and d. However, the first segment (339-355) contains several nonclassical residues in the a and d positions which tend to weaken the hydrophobic interaction along the common interface. Instead, stabilization is achieved by a hydrophobic "coat" formed by the a and d residues and the long aliphatic moieties of lysines and glutamates, extending away from the coiled-coil core. By contrast, the second segment of the kinesin neck (356-370) shows a classical leucine zipper pattern in which most of the hydrophobic residues are buried at the highly symmetrical dimer interface. The end of the neck reveals the structure of a potential coiled-coil "trigger" sequence.
Max-Planck-Unit for Structural Molecular Biology, Notkestrasse 85, Hamburg, D-22603, Germany.
M
M
Thormählen
A
A
Marx
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S
Sack
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E
Mandelkow
D000595:Amino Acid Sequence; D000818:Animals; D018360:Crystallography, X-Ray; D019281:Dimerization; D016547:Kinesins / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017510:Protein Folding; D017433:Protein Structure, Secondary; D051381:Rats; D016415:Sequence Alignment
D016547:Kinesins