Background: Microtubules are built from linear polymers of α-β tubulin dimers (protofilaments) that form a tubular quinary structure. Microtubules assembled from purified tubulin in vitro contain between 10 and 16 protofilaments; however, such structural polymorphisms are not found in cells. This discrepancy implies that factors other than tubulin constrain microtubule protofilament number, but the nature of these constraints is unknown.
Results: Here, we show that acetylation of MEC-12 α-tubulin constrains protofilament number in C. elegans touch receptor neurons (TRNs). Whereas the sensory dendrite of wild-type TRNs is packed with a cross-linked bundle of long, 15-protofilament microtubules, mec-17;atat-2 mutants lacking α-tubulin acetyltransferase activity have short microtubules, rampant lattice defects, and variable protofilament number both between and within microtubules. All-atom molecular dynamics simulations suggest a model in which acetylation of lysine 40 promotes the formation of interprotofilament salt bridges, stabilizing lateral interactions between protofilaments and constraining quinary structure to produce stable, structurally uniform microtubules in vivo.
Conclusions: Acetylation of α-tubulin is an essential constraint on protofilament number in vivo. We propose a structural model in which this posttranslational modification promotes the formation of lateral salt bridges that fine-tune the association between adjacent protofilaments and enable the formation of uniform microtubule populations in vivo.
Download full-text PDF |
Source |
---|---|
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3670109 | PMC |
http://dx.doi.org/10.1016/j.cub.2012.05.012 | DOI Listing |
Nat Commun
January 2025
NMR Based Structural Biology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.
Aggregation intermediates play a pivotal role in the assembly of amyloid fibrils, which are central to the pathogenesis of neurodegenerative diseases. The structures of filamentous intermediates and mature fibrils are now efficiently determined by single-particle cryo-electron microscopy. By contrast, smaller pre-fibrillar α-Synuclein (αS) oligomers, crucial for initiating amyloidogenesis, remain largely uncharacterized.
View Article and Find Full Text PDFJ Biol Chem
December 2024
Protein Expression Laboratory, National Institute of Arthritis and Musculoskeletal and Skin Diseases, National Institutes of Health, Bethesda, Maryland, USA. Electronic address:
Microtubule (MT) function plasticity originates from its composition of α- and β-tubulin isotypes and the post-translational modifications of both subunits. Aspects such as MT assembly dynamics, structure, and anticancer drug binding can be modulated by αβ-tubulin heterogeneity. However, the exact molecular mechanism regulating these aspects is only partially understood.
View Article and Find Full Text PDFDev Cell
December 2024
Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany; Cell Biology and Biophysics Unit, EMBL, 69117 Heidelberg, Germany. Electronic address:
Centrosomes organize microtubules that are essential for mitotic divisions in animal cells. They consist of centrioles surrounded by pericentriolar material (PCM). Questions related to mechanisms of centriole assembly, PCM organization, and spindle microtubule formation remain unanswered, partly due to limited availability of molecular-resolution structural data inside cells.
View Article and Find Full Text PDFNat Commun
November 2024
Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, 37996, USA.
A critical cell cycle checkpoint for most bacteria is the onset of constriction when the septal peptidoglycan synthesis starts. According to the current understanding, the arrival of FtsN to midcell triggers this checkpoint in Escherichia coli. Recent structural and in vitro data suggests that recruitment of FtsN to the Z-ring leads to a conformational switch in actin-like FtsA, which links FtsZ protofilaments to the cell membrane and acts as a hub for the late divisome proteins.
View Article and Find Full Text PDFbioRxiv
April 2024
Structural and Computational Biology Unit, European Molecular Biology Laboratory (EMBL), 69117 Heidelberg, Germany.
Centrosomes organize microtubules that are essential for mitotic divisions in animal cells. They consist of centrioles surrounded by Pericentriolar Material (PCM). Questions related to mechanisms of centriole assembly, PCM organization, and microtubule formation remain unanswered, in part due to limited availability of molecular-resolution structural analyses .
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!