A kinesin-like calmodulin-binding protein in Chlamydomonas: evidence for a role in cell division and flagellar functions.
Kinesin-like calmodulin-binding protein, KCBP, is a novel member of the C-kinesin superfamily first discovered in flowering plants. This minus-end-directed kinesin exhibits Ca(2+)-calmodulin-sensitive motor activity in vitro and has been implicated in trichome morphogenesis and cell division. A homologue of KCBP is also found in the unicellular, biflagellate green alga Chlamydomonas reinhardtii (CrKCBP). Unlike plant cells, Chlamydomonas cells do not form trichomes and do not assemble a phragmoplast before cell division. To test whether CrKCBP is involved in additional microtubule-based processes not observed in plants, we generated antibodies against the putative calmodulin-binding domain and used these antibodies in biochemical and localization studies. In interphase cells CrKCBP primarily localizes near the base of the flagella, although surprisingly, a small fraction also localizes along the length of the flagella. CrKCBP is bound to isolated axonemes in an ATP-dependent fashion and is not a component of the dynein arms, radial spokes or central apparatus. During mitosis, CrKCBP appears concentrated at the centrosomes during prophase and metaphase. However, during telophase and cytokinesis CrKCBP co-localizes with the microtubules associated with the phycoplast. These studies implicate CrKCBP in flagellar functions as well as cell division.
Dymek
Erin E
EE
Dartmouth College, Department of Biological Sciences, 301 Gilman, Hanover, NH 03755, USA.
Goduti
Daniel
D
Kramer
Tal
T
Smith
Elizabeth F
EF
D000255:Adenosine Triphosphate / Q000378:metabolism; D020418:Algal Proteins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002148:Calmodulin-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000502:physiology; D002455:Cell Division / Q000502:physiology*; D016825:Chlamydomonas reinhardtii / Q000166:cytology / Q000502:physiology; D005407:Flagella / Q000378:metabolism*; D016547:Kinesins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D015662:Trimethoprim, Sulfamethoxazole Drug Combination / Q000378:metabolism
D020418:Algal Proteins; D002148:Calmodulin-Binding Proteins; D015800:Protozoan Proteins; D015662:Trimethoprim, Sulfamethoxazole Drug Combination; D000255:Adenosine Triphosphate; D016547:Kinesins