The Coiled-Coil Helix in the Neck of Kinesin

• Published in: Journal of structural biology Vol. 122; no. 1-2; pp. 30 - 41
• Main Authors: Thormählen, M., Marx, A., Sack, S., Mandelkow, E.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 1998
• Subjects: Amino Acid Sequence; Animals; coiled coil; Crystallography, X-Ray; Dimerization; Kinesin - chemistry; microtubules; Models, Chemical; Models, Molecular; Molecular Sequence Data; motility; motor proteins; Protein Folding; Protein Structure, Secondary; Rats; Sequence Alignment; X-ray crystallography; X-ray crystallography; motility; microtubules; motor proteins; coiled coil
• DOI: 10.1006/jsbi.1998.3986
• ISSN: 1047-8477

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 α-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)ntypical 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.