title: Islands containing slowly hydrolyzable GTP analogs promote microtubule rescues.
abstract: Microtubules are dynamic polymers of GTP- and GDP-tubulin that undergo stochastic transitions between growing and shrinking phases. Rescues, the conversion from shrinking to growing, have recently been proposed to be to the result of regrowth at GTP-tubulin islands within the lattice of growing microtubules. By introducing mixed GTP/GDP/GMPCPP (GXP) regions within the lattice of dynamic microtubules, we reconstituted GXP islands in vitro (GMPCPP is the slowly hydrolyzable GTP analog guanosine-5'-[(α,β)-methyleno]triphosphate). We found that such islands could reproducibly induce rescues and that the probability of rescue correlated with both the size of the island and the percentage of GMPCPP-tubulin within the island. The islands slowed the depolymerization rate of shortening microtubules and promoted regrowth more readily than GMPCPP seeds. Together, these findings provide new mechanistic insights supporting the possibility that rescues could be triggered by enriched GTP-tubulin regions and present a new tool for studying such rescue events in vitro.
authors.affiliation: Marine Biological Laboratory Physiology Course, Woods Hole, Massachusetts, United States of America.
authors.forename: Carolina
authors.initials: C
authors.lastname: Tropini
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Roth
authors.forename: Marija
authors.initials: M
authors.lastname: Zanic
authors.forename: Melissa K
authors.initials: MK
authors.lastname: Gardner
authors.forename: Jonathon
authors.initials: J
authors.lastname: Howard
mesh_terms: D006153:Guanosine Diphosphate / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000031:analogs & derivatives / Q000378:metabolism*; D006868:Hydrolysis; D008856:Microscopy, Fluorescence; D008870:Microtubules / Q000378:metabolism*; D056004:Molecular Dynamics Simulation; D011108:Polymers / Q000378:metabolism*; D014404:Tubulin / Q000378:metabolism*
chemical_list: D011108:Polymers; D014404:Tubulin; D006153:Guanosine Diphosphate; C004805:5'-guanylylmethylenebisphosphonate; D006160:Guanosine Triphosphate