Importance of a flexible hinge near the motor domain in kinesin-driven motility.
Conventional kinesin is a molecular motor consisting of an N-terminal catalytic motor domain, an extended stalk and a small globular C-terminus. Whereas the structure and function of the catalytic motor domain has been investigated, little is known about the function of domains outside the globular head. A short coiled-coil region adjacent to the motor domain, termed the neck, is known to be important for dimerization and may be required for kinesin processivity. We now provide evidence that a helix-disrupting hinge region (hinge 1) that separates the neck from the first extended coiled-coil of the stalk plays an essential role in basic motor activity. A fast fungal kinesin from Syncephalastrum racemosum was used for these studies. Deletion, substitution by a coiled-coil and truncation of the hinge 1 region all reduce motor speed and uncouple ATP turnover from gliding velocity. Insertion of hinge 1 regions from two conventional kinesins, Nkin and DmKHC, fully restores motor activity, whereas insertion of putative flexible linkers of other proteins does not, suggesting that hinge 1 regions of conventional kinesins can functionally replace each other. We suggest that this region is essential for kinesin movement in its promotion of chemo-mechanical coupling of the two heads and therefore the functional motor domain should be redefined to include not only the catalytic head but also the adjacent neck and hinge 1 domains.
Adolf-Butenandt-Institut, Zellbiologie, University of Munich, Schillerstrasse 42, 80336 Munich, Germany.
M
M
Grummt
G
G
Woehlke
U
U
Henningsen
S
S
Fuchs
M
M
Schleicher
M
M
Schliwa
D000251:Adenosine Triphosphatases / Q000032:analysis; D000595:Amino Acid Sequence; D019281:Dimerization; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics; D016547:Kinesins / Q000737:chemistry / Q000235:genetics*; D008870:Microtubules / Q000378:metabolism; D020409:Molecular Motor Proteins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D009068:Movement / Q000502:physiology*; D009090:Mucorales; D016254:Mutagenesis, Insertional; D018583:Pliability; D011487:Protein Conformation; D017384:Sequence Deletion
D005656:Fungal Proteins; D020409:Molecular Motor Proteins; D000251:Adenosine Triphosphatases; D016547:Kinesins