A novel type of regulation of the vimentin intermediate filament cytoskeleton by a Golgi protein.
Whether the highly dynamic structure of the vimentin intermediate filament (IF) cytoskeleton responds to cues from cellular organelles, and what proteins might participate in such events is largely unknown. We have shown previously that the Golgi protein formiminotransferase cyclodeaminase (FTCD) binds to vimentin filaments in vivo and in vitro, and that overexpression of FTCD causes dramatic rearrangements of the vimentin IF cytoskeleton (Gao and Sztul, J. Cell Biol. 152, 877-894, 2001). Using real-time imaging, we now show that FTCD causes bundling of individual thinner vimentin filaments into fibers and that the bundling always originates at the Golgi. FTCD appears to be the molecular "glue" since FTCD cross-links vimentin filaments in vitro. To initiate the analysis of structural determinants required for FTCD function in vimentin dynamics, we used structure-based design to generate individual formiminotransferase (FT) and cyclodeaminase (CD) domains, and to produce an enzymatically inactive FTCD. We show that the intact octameric structure is required for FTCD binding to vimentin filaments and for promoting filament assembly, but that eliminating enzymatic activity does not affect FTCD effects on the vimentin cytoskeleton. Our findings indicate that the Golgi protein FTCD is a potent modulator of the vimentin IF cytoskeleton, and suggest that the Golgi might act as a reservoir for proteins that regulate cytoskeletal dynamics.
Gao
Ya-Sheng
YS
Department of Cell Biology, University of Alabama at Birmingham, 35294, USA.
Vrielink
Alice
A
MacKenzie
Robert
R
Sztul
Elizabeth
E
D000642:Ammonia-Lyases / Q000235:genetics* / Q000378:metabolism*; D000818:Animals; D019556:COS Cells; D003001:Cloning, Molecular; D003432:Cross-Linking Reagents / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D051042:Glutamate Formimidoyltransferase; D006056:Golgi Apparatus / Q000378:metabolism*; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D009097:Multienzyme Complexes; D064251:Multifunctional Enzymes; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D051381:Rats; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013997:Time Factors; D014162:Transfection; D014746:Vimentin / Q000378:metabolism*
D003432:Cross-Linking Reagents; D008164:Luminescent Proteins; D009097:Multienzyme Complexes; D064251:Multifunctional Enzymes; D011993:Recombinant Fusion Proteins; D014746:Vimentin; D049452:Green Fluorescent Proteins; D004247:DNA; C494850:Ftcd protein, mouse; D051042:Glutamate Formimidoyltransferase; D000642:Ammonia-Lyases; C500814:Ftcd protein, rat; C020148:formiminotetrahydrofolate cyclodeaminase