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Hotta T, Haynes SE, Blasius TL, Gebbie M, Eberhardt EL, Sept D, Cianfrocco M, Verhey KJ, Nesvizhskii AI, Ohi R. Parthenolide Destabilizes Microtubules by Covalently Modifying Tubulin. Curr Biol 2021; 31:900-907.e6. [PMID: 33482110 DOI: 10.1016/j.cub.2020.11.055] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/02/2020] [Accepted: 11/19/2020] [Indexed: 12/28/2022]
Abstract
Detyrosination of the α-tubulin C-terminal tail is a post-translational modification (PTM) of microtubules that is key for many biological processes.1 Although detyrosination is the oldest known microtubule PTM,2-7 the carboxypeptidase responsible for this modification, VASH1/2-SVBP, was identified only 3 years ago,8,9 precluding genetic approaches to prevent detyrosination. Studies examining the cellular functions of detyrosination have therefore relied on a natural product, parthenolide, which is widely believed to block detyrosination of α-tubulin in cells, presumably by inhibiting the activity of the relevant carboxypeptidase(s).10 Parthenolide is a sesquiterpene lactone that forms covalent linkages predominantly with exposed thiol groups; e.g., on cysteine residues.11-13 Using mass spectrometry, we show that parthenolide forms adducts on both cysteine and histidine residues on tubulin itself, in vitro and in cells. Parthenolide causes tubulin protein aggregation and prevents the formation of microtubules. In contrast to epoY, an epoxide inhibitor of VASH1/2-SVBP,9 parthenolide does not block VASH1-SVBP activity in vitro. Lastly, we show that epoY is an efficacious inhibitor of microtubule detyrosination in cells, providing an alternative chemical means to block detyrosination. Collectively, our work supports the notion that parthenolide is a promiscuous inhibitor of many cellular processes and suggests that its ability to block detyrosination may be an indirect consequence of reducing the polymerization-competent pool of tubulin in cells.
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Affiliation(s)
- Takashi Hotta
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Sarah E Haynes
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA
| | - Teresa L Blasius
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Margo Gebbie
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Emily L Eberhardt
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - David Sept
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, USA
| | - Michael Cianfrocco
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA; Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, USA
| | - Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA
| | - Alexey I Nesvizhskii
- Department of Pathology, University of Michigan, Ann Arbor, MI, USA; Department of Computational Medicine and Bioinformatics, University of Michigan, Ann Arbor, MI, USA
| | - Ryoma Ohi
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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Rai SS, Wolff J. Localization of critical histidyl residues required for vinblastine-induced tubulin polymerization and for microtubule assembly. J Biol Chem 1998; 273:31131-7. [PMID: 9813016 DOI: 10.1074/jbc.273.47.31131] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Vinblastine-induced tubulin polymerization is electrostatically regulated and shows pH dependence with a pI approximately 7.0 suggesting the involvement of histidyl residues. Modification of histidyl residues of tubulin with diethylpyrocarbonate (DEPC) at a mole ratio of 0.74 (DEPC/total His residues) for 3 min at 25 degreesC completely inhibited vinblastine-induced polymerization with little effect on microtubule assembly. Under these conditions DEPC reacts only with histidyl residues. For complete inhibition two histidyl residues have to be modified. Demodification of the carboxyethyl histidyl derivatives by hydroxylamine led to nearly complete recovery of polymerization competence. Labeling with [14C]DEPC localized both of these histidyl residues on beta-tubulin at beta227 and beta264. Similarly, tubulin modification with DEPC for longer times (8 min) resulted in complete inhibition of microtubule assembly, at which time approximately 4 histidyl residues had been modified. This inhibition by DEPC was also reversed by hydroxylamine. The third histidyl residue was found on alpha-tubulin at alpha88. Thus, two charged histidyl residues are obligatorily involved in vinblastine-induced polymerization, whereas a different histidyl residue on a different tubulin monomer is involved in microtubule assembly.
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Affiliation(s)
- S S Rai
- Laboratory of Biochemistry and Genetics, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA
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Szasz J, Yaffe MB, Sternlicht H. Site-directed mutagenesis of alpha-tubulin. Reductive methylation studies of the Lys 394 region. Biophys J 1993; 64:792-802. [PMID: 8097117 PMCID: PMC1262393 DOI: 10.1016/s0006-3495(93)81440-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Previous studies have implicated at least two regions in alpha-tubulin that are important for the regulation of microtubule assembly. These regions include a cluster of basic residues consisting of Arg 390, His 393, and Lys 394 and the highly acidic carboxyl terminus. Lys 394 is highly reactive to HCHO and NaCNBH3. The reductive methylation of Lys 394 by these reagents is thought to be responsible for the profound inhibitory effects of low concentrations of HCHO on microtubule assembly (cf. Szasz J., M. B. Yaffe, M. Elzinga, G. S. Blank, and H. Sternlicht. 1986. Biochemistry. 25:4572-4582). In this study we reexamined the basis for this inhibition. Lys 394 in a human keratinocyte alpha-tubulin (k alpha 1) was replaced by a glutamic acid residue using site-directed mutagenesis. The mutant K394E was synthesized in vitro using rabbit reticulocyte lysates, and its ability to coassemble with bovine brain microtubule protein (MTP) before and after reaction with HCHO and NaCNBH3 was compared with that of wild-type. No differences in the coassemblies of the unmethylated proteins were detected suggesting that Lys 394 is not essential for microtubule assembly. However, methylated K394E prepared at low HCHO concentrations (< 1 mM) incorporated into microtubules to a greater extent (approximately 30-40%) than methylated wild-type. This result is consistent with the hypothesis that methylation of Lys 394 interferes with microtubule assembly. However, the extent of protection afforded by the replacement of Lys 394 with Glu 394 was less than half as large as that predicted from the earlier studies. We tentatively conclude that another residue(s) besides Lys 394 contributes significantly to the assembly-inhibition observed with low concentrations of HCHO. Since this residue(s) is less reactive than Lys 394, it would have to inhibit assembly substoichiometrically when methylated. Potential candidates for this residue include bulk lysyl residue(s), a lysyl residue(s) with intermediate reactivity toward HCHO, and the NH2-termini. The NH2-termini are especially attractive candidates since they appear to have a structural role in microtubule assembly.
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Affiliation(s)
- J Szasz
- Department of Pharmacology, Case Western Reserve School of Medicine, Cleveland, Ohio 44106
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