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Di Gregorio E, Staelens M, Hosseinkhah N, Karimpoor M, Liburd J, Lim L, Shankar K, Tuszyński JA. Raman Spectroscopy Reveals Photobiomodulation-Induced α-Helix to β-Sheet Transition in Tubulins: Potential Implications for Alzheimer's and Other Neurodegenerative Diseases. NANOMATERIALS (BASEL, SWITZERLAND) 2024; 14:1093. [PMID: 38998698 PMCID: PMC11243591 DOI: 10.3390/nano14131093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2024] [Revised: 06/03/2024] [Accepted: 06/12/2024] [Indexed: 07/14/2024]
Abstract
In small clinical studies, the application of transcranial photobiomodulation (PBM), which typically delivers low-intensity near-infrared (NIR) to treat the brain, has led to some remarkable results in the treatment of dementia and several neurodegenerative diseases. However, despite the extensive literature detailing the mechanisms of action underlying PBM outcomes, the specific mechanisms affecting neurodegenerative diseases are not entirely clear. While large clinical trials are warranted to validate these findings, evidence of the mechanisms can explain and thus provide credible support for PBM as a potential treatment for these diseases. Tubulin and its polymerized state of microtubules have been known to play important roles in the pathology of Alzheimer's and other neurodegenerative diseases. Thus, we investigated the effects of PBM on these cellular structures in the quest for insights into the underlying therapeutic mechanisms. In this study, we employed a Raman spectroscopic analysis of the amide I band of polymerized samples of tubulin exposed to pulsed low-intensity NIR radiation (810 nm, 10 Hz, 22.5 J/cm2 dose). Peaks in the Raman fingerprint region (300-1900 cm-1)-in particular, in the amide I band (1600-1700 cm-1)-were used to quantify the percentage of protein secondary structures. Under this band, hidden signals of C=O stretching, belonging to different structures, are superimposed, producing a complex signal as a result. An accurate decomposition of the amide I band is therefore required for the reliable analysis of the conformation of proteins, which we achieved through a straightforward method employing a Voigt profile. This approach was validated through secondary structure analyses of unexposed control samples, for which comparisons with other values available in the literature could be conducted. Subsequently, using this validated method, we present novel findings of statistically significant alterations in the secondary structures of polymerized NIR-exposed tubulin, characterized by a notable decrease in α-helix content and a concurrent increase in β-sheets compared to the control samples. This PBM-induced α-helix to β-sheet transition connects to reduced microtubule stability and the introduction of dynamism to allow for the remodeling and, consequently, refreshing of microtubule structures. This newly discovered mechanism could have implications for reducing the risks associated with brain aging, including neurodegenerative diseases like Alzheimer's disease, through the introduction of an intervention following this transition.
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Affiliation(s)
- Elisabetta Di Gregorio
- Department of Physics, Faculty of Science, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Department of Mechanical and Aerospace Engineering (DIMEAS), Faculty of Biomedical Engineering, Polytechnic University of Turin, 10129 Turin, Italy
- Department of Physics, Freie Universität Berlin, 14195 Berlin, Germany
| | - Michael Staelens
- Department of Physics, Faculty of Science, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Instituto de Física Corpuscular, CSIC–Universitat de València, Carrer Catedràtic José Beltrán 2, 46980 Paterna, Spain
| | | | | | | | - Lew Lim
- Vielight Inc., Toronto, ON M4Y 2G8, Canada
| | - Karthik Shankar
- Department of Electrical and Computer Engineering, Faculty of Engineering, University of Alberta, Edmonton, AB T6G 1H9, Canada
| | - Jack A. Tuszyński
- Department of Physics, Faculty of Science, University of Alberta, Edmonton, AB T6G 2E1, Canada
- Department of Mechanical and Aerospace Engineering (DIMEAS), Faculty of Biomedical Engineering, Polytechnic University of Turin, 10129 Turin, Italy
- Department of Data Science and Engineering, Silesian University of Technology, 44-100 Gliwice, Poland
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Maddula V, Holtzman NS, Nagan MC, Rotenberg SA. Phosphomimetic Mutation at Ser165 of α-Tubulin Promotes the Persistence of GTP Caps in Microtubules. Biochemistry 2022; 61:1508-1516. [PMID: 35799350 DOI: 10.1021/acs.biochem.2c00154] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Protein kinase C (PKC)-mediated phosphorylation of α-tubulin at Ser165 or expression of phosphomimetic (S165D)-α-tubulin stimulates microtubule (MT) polymerization (Cytoskeleton 2014, 71, 257-272). Ser165 lies near the interface between adjacent αβ-tubulin heterodimers and helix H8, which contains Glu254, the catalytic residue in α-tubulin that hydrolyzes the exchangeable GTP in β-tubulin (β:GTP) and triggers MT depolymerization. It was hypothesized that S165D, a phosphomimetic variant of α-tubulin, perturbs the alignment of α:Glu254 with respect to β:GTP, thereby impairing its hydrolysis. Molecular simulations were performed with cryoEM structures of MTs (PDB ID: 3J6E) in which phosphomimetic S165D or control S165N had been substituted. Unlike native and S165N structures, the distance between S165D and α:Glu254 increased by 0.6 Å, while the distance between α:Glu254 and β:GTP decreased by 0.4 Å. Rotation of β:GTP by 4 Å occurred in the S165D variant, whereas β:GTP in the S165N control was unchanged from the native structure. Additionally, the S165D variant exhibited an altered pattern of H-bonding to β:GTP, including the loss of three H-bonds. The significance of these findings to β:GTP hydrolysis was analyzed in MCF-10A human breast cells treated with an antibody that detects GTP-bound tubulin. Compared with controls, GTP-tubulin signals were at higher levels in cells that ectopically expressed S165D-α-tubulin (TUBA1C) or had been treated with PKC activator DAG-lactone to induce phosphorylation of Ser165 in native α-tubulin. These findings support a model whereby conformational changes induced by Ser165 phosphorylation alter the spatial relationship between β:GTP and α:Glu254, thereby slowing GTP hydrolysis and promoting GTP caps.
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Affiliation(s)
- Vinay Maddula
- Department of Chemistry, Adelphi University, One South Ave, Garden City, New York 11530, United States
| | - Nathalia S Holtzman
- Department of Biology, Queens College - The City University of New York, Flushing, New York 11367-1597, United States.,PhD Program in Biochemistry, The Graduate Center of The City University of New York, 365 5th Ave, New York, New York 10016, United States
| | - Maria C Nagan
- Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400, United States
| | - Susan A Rotenberg
- Department of Chemistry & Biochemistry, Queens College - The City University of New York, Flushing, New York 11367-1597, United States.,PhD Program in Biochemistry, The Graduate Center of The City University of New York, 365 5th Ave, New York, New York 10016, United States
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Fulton C. The Amazing Evolutionary Complexity of Eukaryotic Tubulins: Lessons from Naegleria and the Multi-tubulin Hypothesis. Front Cell Dev Biol 2022; 10:867374. [PMID: 35547824 PMCID: PMC9081340 DOI: 10.3389/fcell.2022.867374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 02/22/2022] [Indexed: 11/13/2022] Open
Abstract
The multi-tubulin hypothesis proposed in 1976 was motivated by finding that the tubulin to build the flagellar apparatus was synthesized de novo during the optional differentiation of Naegleria from walking amoebae to swimming flagellates. In the next decade, with the tools of cloning and sequencing, we were able to establish that the rate of flagellar tubulin synthesis in Naegleria is determined by the abundance of flagellar α- and β-tubulin mRNAs. These experiments also established that the tubulins for Naegleria mitosis were encoded by separate, divergent genes, candidates for which remain incompletely characterized. Meanwhile an unanticipated abundance of tubulin isotypes has been discovered by other researchers. Together with the surprises of genome complexity, these tubulin isotypes require us to rethink how we might utilize the opportunities and challenges offered by the evolutionary diversity of eukaryotes.
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Affiliation(s)
- Chandler Fulton
- Department of Biology, Brandeis University, Waltham, MA, United States
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Linck RW, Chemes H, Albertini DF. The axoneme: the propulsive engine of spermatozoa and cilia and associated ciliopathies leading to infertility. J Assist Reprod Genet 2016; 33:141-56. [PMID: 26825807 PMCID: PMC4759005 DOI: 10.1007/s10815-016-0652-1] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Accepted: 01/03/2016] [Indexed: 01/08/2023] Open
Affiliation(s)
- Richard W Linck
- Department of Genetics, Cell Biology and Development, University of Minnesota, Minneapolis, MN, 55455, USA.
| | - Hector Chemes
- Center for Research in Endocrinology, National Research Council, CEDIE-CONICET, Endocrinology Division, Buenos Aires Children's Hospital, Gallo 1330, C1425SEFD, Buenos Aires, Argentina.
| | - David F Albertini
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS, 66160, USA. .,The Center for Human Reproduction, New York, NY, USA.
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Loza-Huerta A, Vera-Estrella R, Darszon A, Beltrán C. Certain Strongylocentrotus purpuratus sperm mitochondrial proteins co-purify with low density detergent-insoluble membranes and are PKA or PKC-substrates possibly involved in sperm motility regulation. Biochim Biophys Acta Gen Subj 2013; 1830:5305-15. [DOI: 10.1016/j.bbagen.2013.07.029] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2012] [Revised: 06/24/2013] [Accepted: 07/27/2013] [Indexed: 12/14/2022]
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Morejohn LC, Bureau TE, Tocchi LP, Fosket DE. Tubulins from different higher plant species are immunologically nonidentical and bind colchicine differentially. Proc Natl Acad Sci U S A 2010; 81:1440-4. [PMID: 16593430 PMCID: PMC344851 DOI: 10.1073/pnas.81.5.1440] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We have initiated immunological and drug-binding studies on the tubulins from different higher plant species. Antibodies were raised against electrophoretically separated rose (Rosa sp.) tubulin alpha- and beta-subunits and characterized by immunoblot autoradiographic assays. Each IgG preparation bound to its antigen and cross-reacted differentially with the respective tubulin subunits from an alga, sea urchin, rabbit, and cow. Antigenic determinants were shared more among the beta-subunits than among the alpha-subunits from these organisms. Tubulins were isolated from cultured cells of carrot (Daucus carota) and hibiscus (Hibiscus rosa-senensis). Immunoautoradiography and quantitation of cross-reactivity on blots showed nonidentity among homologous subunits from rose, carrot, hibiscus, and alga tubulins, with more antigenic differences among alpha-subunits than among beta-subunits. Comparative colchicine-binding assays showed that rose and hibiscus tubulins bound 33% and 65%, respectively, of the colchicine bound by carrot tubulin and that higher plant tubulins bound much less colchicine than bovine brain tubulin under identical conditions.
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Affiliation(s)
- L C Morejohn
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92717
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Griffin J, Carbone A, Delgado-Rivera R, Meiners S, Uhrich KE. Design and evaluation of novel polyanhydride blends as nerve guidance conduits. Acta Biomater 2010; 6:1917-24. [PMID: 19941978 DOI: 10.1016/j.actbio.2009.11.023] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2009] [Revised: 11/16/2009] [Accepted: 11/17/2009] [Indexed: 11/19/2022]
Abstract
Implantable biodegradable nerve guidance conduits (NGCs) have the potential to align and support regenerating cells, as well as prevent scar formation. In this study in vitro bioassays and in vivo material evaluations were performed using a nerve guidance conduit material made from a novel polyanhydride blend. In vitro cytotoxicity studies with both fibroblasts and primary chick neurons demonstrated that the proposed polyanhydride blend was non-cytotoxic. Subcutaneous implantation for 7days in rats resulted in an initial fibrin matrix, minimal macrophage presence and angiogenesis in the surrounding tissues. Nerve guidance conduits fabricated from the proposed polyanhydride blend material may serve as favorable biocompatible tissue engineering devices.
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Affiliation(s)
- Jeremy Griffin
- Department of Biomedical Engineering, Rutgers University, 599 Taylor Road, Piscataway, NJ 08854, USA
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Song M, Uhrich KE. Optimal Micropattern Dimensions Enhance Neurite Outgrowth Rates, Lengths, and Orientations. Ann Biomed Eng 2007; 35:1812-20. [PMID: 17616821 DOI: 10.1007/s10439-007-9348-0] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2006] [Accepted: 06/22/2007] [Indexed: 10/23/2022]
Abstract
Micropattern dimensions can significantly influence neurite outgrowth orientation, rate, and length. Laminin micropatterns of various widths from 10 to 50 microm at 10 microm intervals separated by 40 microm spaces were generated on poly(methyl methacrylate) surfaces using microscale plasma-initiated patterning (microPIP). Dissociated dorsal root ganglion (DRG) neurons were seeded on the micropatterned surfaces and cultured for 24 h in serum-free media. Neurite outgrowth numbers, lengths, rates, and orientations were measured on all micropatterned substrates. The results indicated that the dimension of the laminin pattern influenced the neurite outgrowth length, rate, and orientation, but not the numbers of neurite outgrowth. Neurons on more than 30 microm wide laminin pattern showed faster neurite outgrowth compared to other dimensions, and relatively low orientation at 50 microm pattern dimensions. Neurites at 40 microm laminin pattern widths demonstrated the fastest outgrowth rates and were highly oriented. The 40 microm laminin dimension is wide enough to provide sufficient laminin amounts for neuron growth and narrow enough to efficiently guide neurites. Based on these results, adhesive protein micropatterns of 40 microm dimensions are recommended when investigating DRG neurons.
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Affiliation(s)
- MinJung Song
- Department of Biomedical Engineering, Rutgers University, 617 Bowser Road, Piscataway, NJ 08854, USA
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9
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Juul ME, Dornish JM, Juul NO, Pettersen EO, Oftebro R. Effect of two pyrimidine analogs on accumulation of tubulin in NHIK 3025 cells. Mol Cell Biochem 1990; 96:117-26. [PMID: 2274046 DOI: 10.1007/bf00420903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Accumulation of tubulin as compared with the accumulation of total cellular protein in human NHIK 3025 cells treated with the sulfone 2-(2-thenyl)sulfonyl-5-bromopyrimidine (NY 4137) and the sulfoxide 2-(2-thenyl)sulfinyl-5-bromopyrimidine (NY 4138), two mitotic inhibitors, were investigated by two-parametric flow cytometry. Following a 4 h treatment with NY 4137 tubulin accumulation is inhibited while total protein continues to accumulate. After treatment for 4 h with NY 4138 the accumulation of total protein is approximately constant, while the accumulation of tubulin is reduced although not to the same degree as that found for NY 4137-treated cells. In addition, the percentage tubulin SH-groups (6.89 +/- 0.14) remaining after treatment of purified rat brain tubulin with NY 4137 or NY 4138 was determined. Treatment with 0.0125 mM NY 4137 reduced the number of tubulin SH-groups detectable with dithiobis benzoate or from 6.89 +/- 0.14 before treatment to about 4 after treatment. However, practically all SH-groups of tubulin remain detectable following treatment with the same concentration of NY 4138. From the results described in this report we infer that NY 4137 binds to tubulin SH-groups and that inhibition of tubulin accumulation follows as a secondary effect.
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Affiliation(s)
- M E Juul
- Department of Tissue Culture, Norwegian Radium Hospital, Montebello, Oslo
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10
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Hamilton AJ, Bartholomew MA, Hay RJ. Immunogold electron microscopical detection of tubulin and actin within mycelial phase Histoplasma capsulatum capsulatum and H. capsulatum duboisii. Mycoses 1989; 32:405-10. [PMID: 2797056 DOI: 10.1111/j.1439-0507.1989.tb02271.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Immunogold electron microscopy using LR Gold as a resin was undertaken to determine the distribution of actin and tubulin within the hyphae of Histoplasma capsulatum capsulatum and H. capsulatum duboisii. Both of these proteins were found throughout the cytoplasm when probed with the appropriate monoclonal antibodies.
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11
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Chang SL, Flavin M. Tubulin tyrosination in Crithidia: modifying enzymes and modification states of tubulin. CELL MOTILITY AND THE CYTOSKELETON 1988; 10:400-9. [PMID: 3180253 DOI: 10.1002/cm.970100307] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
An enzyme that adds C-terminal tyrosine to tubulin has been identified in Crithidia fasciculata. It tyrosinates Crithidia, but not brain, tubulin and is specific for the alpha chain. Crithidia cells could not be shown to fix tyrosine in the absence of protein synthesis, which is consistent with the pattern of distribution of C-terminal tyrosine in tubulin from different subcellular compartments of this protozoan. Terminal tyrosine was present in about 5% of flagellar alpha chain from cells in stationary phase and 20% from cells from midlog phase; none was detected in tubulin from cytosol or the subpellicular corset. In contrast to mammalian cells, in which a higher state of tyrosinolation characterizes recently assembled or unstable microtubules, terminal tyrosine was present only in the most stable polymer, the flagellar doublet microtubules.
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Affiliation(s)
- S L Chang
- Laboratory of Cell Biology, National Heart, Lung, and Blood Institute, Bethesda, Maryland 20892
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12
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Chattopadhyay D, Banerjee AK. Two separate domains within vesicular stomatitis virus phosphoprotein support transcription when added in trans. Proc Natl Acad Sci U S A 1987; 84:8932-6. [PMID: 2827161 PMCID: PMC299665 DOI: 10.1073/pnas.84.24.8932] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The structural phosphoprotein NS of vesicular stomatitis virus, in association with the virion-associated RNA polymerase L protein, transcribes the genome ribonucleoprotein template in vitro. It contains an acidic N-terminal domain and two distinct domains at the C-terminal end that are involved in binding to the polymerase protein and the template RNA enwrapped with the nucleocapsid protein. In the present study, the portions of the NS gene that encode the N- and C-terminal domains of the protein were cloned in pGEM vectors and expressed by in vitro transcription and translation. It was shown that two polypeptides obtained by translation of the encoded mRNAs support RNA synthesis in vitro in a reconstitution reaction when they are added together in trans. Moreover, the N-terminal domain can be functionally substituted by structurally similar polypeptides.
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Affiliation(s)
- D Chattopadhyay
- Roche Institute of Molecular Biology, Roche Research Center, Nutley, NJ 07110
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13
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Marks MD, West J, Weeks DP. The relatively large beta-tubulin gene family of Arabidopsis contains a member with an unusual transcribed 5' noncoding sequence. PLANT MOLECULAR BIOLOGY 1987; 10:91-104. [PMID: 24277495 DOI: 10.1007/bf00016147] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We have characterized the beta-tubulin gene family of Arabidopsis thaliana. Five distinct genes were cloned and analyzed by restriction enzyme mapping and cross-hybridization studies. Three of the genes appear to be dispersed, whereas two others are linked within 1.5 kb of one another. The two linked genes are closely related and appear to have resulted from a fairly recent duplication. The three dispersed genes do not cross-hybridize to one another or to the two linked genes under highly stringent hybridization conditions, suggesting that they arose from more ancient duplications. From Southern analysis we estimate that there are a total of between six and ten beta-tubulin genes in Arabidopsis. Additional analyses indicate that the gene family is equal in size or larger than those in other plants, but significantly smaller than those in related Brassica species. Sequence determination of one of the Arabidopsis genes revealed a highly unusual transcribed leader sequence. The leader contains two fairly long tracks of adenines. One is located toward the 5' end of the mRNA and the other is just before the initiation codon. A track of uridines is located between the adenine tracks. This leader can form two different secondary structures that may have regulatory significance.
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Affiliation(s)
- M D Marks
- Sandoz Crop Protection Corp., Zoecon Research Institute, 975 California Ave., 94304, Palo Alto, CA, USA
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14
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White E, Katz ER. Biochemical and genetic approaches to microtubule function in Dictyostelium discoideum. Methods Cell Biol 1987; 28:245-59. [PMID: 3298993 DOI: 10.1016/s0091-679x(08)61649-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Methods have been developed for analyzing tubulin and microtubules from the cellular slime mold D. discoideum. alpha- and beta-tubulin have been identified on high-resolution 2D gels, and microtubules have been isolated in cytoskeleton preparations from amoebae (White et al., 1983). These studies have revealed properties unique to Dictyostelium tubulin. Amoebal microtubules can be visualized by indirect immunofluorescence, which has aided in the identification of inhibitors which specifically depolymerize microtubules and block amoebae in mitosis. The mitotic inhibitors CIPC, NOC, and TBZ have been used to select resistant mutants which are currently the subjects of biochemical, morphological, and genetic analysis (Katz et al., 1982; White, 1983). One mitotic inhibitor-resistant mutant, CIPC 6, was found to be temperature-sensitive for growth at 27 degrees C as well as CIPC-resistant. At the restrictive temperature amoebae from this mutant are deficient in the passage through mitosis. After incubation for 12 hours at the restrictive temperature, 20% of the CIPC 6 amoebae displayed condensed chromosomes, compared to 2% at the permissive temperature, as determined by Giemsa staining. Examination of the microtubules of this mutant by indirect immunofluorescence showed abnormal spindle microtubule formation at the restrictive temperature, which is the likely cause of the mitotic arrest (White, 1983). Cytoplasmic microtubules were also disrupted in nonmitotic amoebae of CIPC 6 at 27 degrees C. This temperature-sensitive loss of microtubule function suggested the possibility that tubulin from CIPC 6 might be altered. When tubulin from CIPC 6 was examined on 2D gels, no reproducible electrophoretic change was observed from that of the wild type. Through further characterization of mitotic inhibitor-resistant mutants like CIPC 6, more mitotic or microtubule mutants will be identified. Among these mutants, some should contain electrophoretically altered tubulin, microtubule-associated proteins, or components of the amoebal cytoskeleton. Possessing Dictyostelium mutants with known biochemical alterations in cytoskeletal proteins should reveal significant information regarding the function of these proteins in eukaryotic growth and development.
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15
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Juliano C, Rubino S, Zicconi D, Cappuccinelli P. An immunofluorescent study of the microtubule organization in Trichomonas vaginalis using antitubulin antibodies. THE JOURNAL OF PROTOZOOLOGY 1986; 33:56-9. [PMID: 3514904 DOI: 10.1111/j.1550-7408.1986.tb05557.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The flagellated protozoon Trichomonas vaginalis, parasite of the human urogenital tract, possesses a well developed microtubule system organized in highly differentiated structures. We have shown by immunoblotting that monospecific anti-sheep brain tubulin antibodies are able to react with the microtubular tubulin of T. vaginalis. These antibodies were used to study the microtubular system of T. vaginalis both in interphase and mitosis by indirect immunofluorescence. The interphase microtubular pattern, characterized by an axostyle, a pelta, four anterior flagella, and a recurrent flagellum, displayed remarkable changes at the onset of mitosis: the axostyle disappeared, and two pole bodies connected by a short spindle became evident; chromosomal fibers arose while pole-to-pole fibers elongated. The last phases of mitosis were marked by the disappearance of chromosomal fibers, the appearance of two small axostyles, and the depolymerization of the pole-to-pole bundle. At the end of mitosis, the normal interphase microtubule pattern was observed.
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16
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Amino-terminal processing of mutant forms of yeast iso-1-cytochrome c. The specificities of methionine aminopeptidase and acetyltransferase. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(18)89033-0] [Citation(s) in RCA: 186] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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17
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L'Hernault SW, Rosenbaum JL. Reversal of the posttranslational modification on Chlamydomonas flagellar alpha-tubulin occurs during flagellar resorption. J Cell Biol 1985; 100:457-62. [PMID: 3968171 PMCID: PMC2113451 DOI: 10.1083/jcb.100.2.457] [Citation(s) in RCA: 72] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
We previously have shown that a posttranslational modification of alpha-tubulin takes place in the flagellum during Chlamydomonas flagellar assembly (L'Hernault, S. W., and J. L. Rosenbaum, 1983, J. Cell Biol., 97:258-263). In this report, we show that the posttranslationally modified alpha-3 tubulin is changed back to its unmodified alpha-1 precursor form during the microtubular disassembly that takes place during flagellar resorption. These data indicate that the addition and removal of a posttranslational modification on alpha-tubulin might be a control step in the assembly and disassembly of flagella.
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18
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Ludueña RF, Roach MC, Jordan MA, Murphy DB. Different reactivities of brain and erythrocyte tubulins toward a sulfhydryl group-directed reagent that inhibits microtubule assembly. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(20)71237-8] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Sullivan KF, Cleveland DW. Sequence of a highly divergent beta tubulin gene reveals regional heterogeneity in the beta tubulin polypeptide. J Biophys Biochem Cytol 1984; 99:1754-60. [PMID: 6490718 PMCID: PMC2113369 DOI: 10.1083/jcb.99.5.1754] [Citation(s) in RCA: 61] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The nucleotide sequence of a chicken genomic DNA segment containing the chicken beta 4 tubulin gene has been determined. The predicted amino acid sequence of beta 4 is surprisingly divergent from that of the chicken beta 2 gene that encodes the dominant neural beta tubulin. beta 4 differs from beta 2 at 36 residue positions and encodes a polypeptide that is four amino acids longer, yielding a divergence of 8.9% between the two beta tubulin isotypes. While many of the amino acid substitutions are conservative, several involve significant alteration in the physiochemical properties of the residue. Furthermore, the amino acid substitution positions are not randomly located within the primary sequence but are distinctly clustered: major divergence occurs in the carboxy-terminal region beyond residue 430 and within the second protein coding exon segments of the genes. In addition, large regions of absolute sequence conservation are also present. Certain sequences within the heterogeneous regions are conserved in other species, indicating that these regions are under positive evolutionary selection pressure and are therefore probably essential for some aspect of beta-tubulin function. These findings strongly suggest that regional amino acid sequence heterogeneity may play an important role in the establishment of functionally differentiated beta tubulin polypeptides.
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Repeated consensus sequence and pseudopromoters in the four coordinately regulated tubulin genes of Chlamydomonas reinhardi. Mol Cell Biol 1984. [PMID: 6738533 DOI: 10.1128/mcb.4.6.1115] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The 5' coding and promoter regions of the four coordinately regulated tubulin genes of Chlamydomonas reinhardi have been mapped and sequenced. DNA sequencing data shows that the predicted N-terminal amino acid sequences of Chlamydomonas alpha- and beta-tubulins closely match that of tubulins of other eucaryotes. Within the alpha 1- and alpha 2-tubulin gene set and the beta 1- and beta 2-tubulin gene set, both nucleotide sequence and intron placement are highly conserved. Transcription initiation sites have been located by primer extension analysis at 140, 141, 159, and 132 base pairs upstream of the translation initiator codon for the alpha 1-, alpha 2-, beta 1-, and beta 2-tubulin genes, respectively. Among the structures with potential regulatory significance, the most striking is a 16-base-pair consensus sequence [GCTC(G/C)AAGGC(G/T)(G/C)--(C/A)(C/A)G] which is found in multiple copies immediately upstream of the TATA box in each of the four genes. An unexpected discovery is the presence of pseudopromoter regions in two of the transcribed tubulin genes. One pseudopromoter region is located 400 base pairs upstream of the authentic alpha 2-tubulin gene promoter, whereas the other is located within the transcribed 5' noncoding region of the beta 1-tubulin gene.
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21
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Wilson L, Miller HP, Pfeffer TA, Sullivan KF, Detrich HW. Colchicine-binding activity distinguishes sea urchin egg and outer doublet tubulins. J Biophys Biochem Cytol 1984; 99:37-41. [PMID: 6539784 PMCID: PMC2275638 DOI: 10.1083/jcb.99.1.37] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
The colchicine-binding activity of tubulin has been utilized to distinguish the tubulins from two distinct microtubule systems of the same species, the sea urchin Strongylocentrotus purpuratus. We have analyzed the colchicine-binding affinities of highly purified tubulins from the unfertilized eggs and from the flagellar outer doublet microtubules by van't Hoff analysis, and have found significant differences in the free energy, enthalpy, and entropy changes characterizing the binding of colchicine to the two tubulins. The data indicate that significant chemical differences in the tubulins from the two functionally distinct microtubule systems exist, and that the differences are expressed in the native forms of the tubulins. Our findings are discussed in terms of the possibility that the colchicine-binding site may be an important regulatory site on the tubulin molecule.
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22
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Stambaugh RL, Nicosia SV. Localization of tubulin and microtubules of in vivo fertilized rabbit oocytes. JOURNAL OF ANDROLOGY 1984; 5:259-64. [PMID: 6381445 DOI: 10.1002/j.1939-4640.1984.tb00786.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The presence of tubulin throughout what appears to be sperm penetration tunnels of in vivo fertilized rabbit oocytes was demonstrated by both immunofluorescence and transmission electron microscopy, using fluorescein and peroxidase-labeled antibodies, respectively. In approximately half the fertilized oocytes examined, intact microtubules were found at the point of entry of the spermatozoon into the zona pellucida, while amorphous deposits were found throughout the remainder of the tunnel, starting at the point of entry into the matrix of the corona radiata cell layer, and continuing to the perivitelline space. These continuous deposits of tubulin suggest that, in the rabbit, acrosomal microtubule-like structures may perform a role in mammalian fertilization, possibly as an enzyme binding or delivery system, although other functions are possible. No deposition of actin was detectable in these tunnels.
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23
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Brunke KJ, Anthony JG, Sternberg EJ, Weeks DP. Repeated consensus sequence and pseudopromoters in the four coordinately regulated tubulin genes of Chlamydomonas reinhardi. Mol Cell Biol 1984; 4:1115-24. [PMID: 6738533 PMCID: PMC368880 DOI: 10.1128/mcb.4.6.1115-1124.1984] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
The 5' coding and promoter regions of the four coordinately regulated tubulin genes of Chlamydomonas reinhardi have been mapped and sequenced. DNA sequencing data shows that the predicted N-terminal amino acid sequences of Chlamydomonas alpha- and beta-tubulins closely match that of tubulins of other eucaryotes. Within the alpha 1- and alpha 2-tubulin gene set and the beta 1- and beta 2-tubulin gene set, both nucleotide sequence and intron placement are highly conserved. Transcription initiation sites have been located by primer extension analysis at 140, 141, 159, and 132 base pairs upstream of the translation initiator codon for the alpha 1-, alpha 2-, beta 1-, and beta 2-tubulin genes, respectively. Among the structures with potential regulatory significance, the most striking is a 16-base-pair consensus sequence [GCTC(G/C)AAGGC(G/T)(G/C)--(C/A)(C/A)G] which is found in multiple copies immediately upstream of the TATA box in each of the four genes. An unexpected discovery is the presence of pseudopromoter regions in two of the transcribed tubulin genes. One pseudopromoter region is located 400 base pairs upstream of the authentic alpha 2-tubulin gene promoter, whereas the other is located within the transcribed 5' noncoding region of the beta 1-tubulin gene.
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24
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Purich DL, Kristofferson D. Microtubule assembly: a review of progress, principles, and perspectives. ADVANCES IN PROTEIN CHEMISTRY 1984; 36:133-212. [PMID: 6382962 DOI: 10.1016/s0065-3233(08)60297-1] [Citation(s) in RCA: 80] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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25
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Alexandraki D, Ruderman JV. Evolution of alpha q- and beta-tubulin genes as inferred by the nucleotide sequences of sea urchin cDNA clones. J Mol Evol 1983; 19:397-410. [PMID: 6317873 DOI: 10.1007/bf02102315] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Evolutionary studies on the tubulin multigene families were initiated by nucleotide sequence analysis of cDNA clones complementary to sea urchin (Lytechinus pictus) testis alpha- and beta-tubulin cDNA clones (p beta 1, p beta 2, p beta e) demonstrated the existence of tubulin mRNA heterogeneity. p beta 2 and p beta 3 contain identical tubulin-coding regions and extremely similar 3' untranslated sequences, including a polyadenylation signal (AAUAAA). However, p beta 2 contains an additional region of 3' untranslated sequence which includes a second polyadenylation signal. These two sequences may be allelic, representing products of alternative transcription termination or processing pathways. p beta 1 and p beta 2 (or p beta 3) cDNAs almost certainly correspond to transcripts of distinct but evolutionarily related genes. Examination of the available coding portions showed that they differ only by a few silent nucleotide substitutions and the deletion/insertion of one codon; most of the differences are clustered within the last 15 3'-end codons. In contrast, their 3' untranslated sequences are considerably divergent. Nucleotide alignment in this region was feasible by considering specific point and segmental mutations, mainly T in equilibrium or formed from C transitions and small deletions/insertions associated with small direct repeats. The sea urchin alpha- and beta-tubulin cDNA and corresponding protein sequences were compared with previously described tubulin cDNA and protein sequences from other organisms. Both alpha and beta tubulins are very conserved proteins, evolving with a rate comparable to that of histones. Analysis of the nucleotide divergence of the coding cDNA regions showed that replacement sites have changed with a rate 20-175 times lower than that of the silent sites. Among the 177 codons compared between the sea urchin testis and chick brain beta-tubulin cDNAs, there are 7 conservative amino acid replacements and the deletion/insertion of two codons. Most of these changes are clustered near the C-terminus. The 161-amino acid portion of chick brain, rat and porcine alpha-tubulin sequences differs by 3 conservative amino acid replacements from the corresponding sea urchin testis alpha-tubulin sequence. The compared interspecies 3' untranslated sequences are very divergent.
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26
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White E, Tolbert EM, Katz ER. Identification of tubulin in Dictyostelium discoideum: characterization of some unique properties. J Cell Biol 1983; 97:1011-9. [PMID: 6352709 PMCID: PMC2112620 DOI: 10.1083/jcb.97.4.1011] [Citation(s) in RCA: 34] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
We used three antitubulin antibodies to localize Dictyostelium tubulin subunits on two-dimensional polyacrylamide gels by Western blotting. All three antibodies, a polyclonal antibody against sea urchin alpha- and beta-tubulin and two monoclonal antibodies against yeast alpha-tubulin, recognize the same set of polypeptides with a molecular weight of 55,000 while focusing at a pH far more basic than all other tubulins. Each antibody specifically stains the microtubule system of slime mold amoebae by indirect immunofluorescence. The microtubule system can be isolated as a major component of the amoeba cytoskeleton, and these preparations are greatly enriched for the presumptive tubulin subunits. The microtubules of these cytoskeletons are resistant to being depolymerized by millimolar concentrations of calcium, while they retain their cold sensitivity. Comparison of peptide maps of slime mold and brain alpha-tubulins indicates that the proteins are related but not identical. Possible explanations for these unusual characteristics are discussed.
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27
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Abstract
The arrangement of developmentally regulated alpha- and beta-tubulin genes has been studied in the parasitic protozoan Leishmania enriettii by using Southern blot hybridization analysis. The alpha-tubulin genes occur in a tandem repeat whose monomeric unit may be represented by a 2-kilobase PstI fragment. Similarly, the beta-tubulin genes probably occur in a separate tandem repeat consisting of approximately 4-kilobase units unlinked to the alpha-tubulin repeats.
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28
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Seebeck T, Whittaker PA, Imboden MA, Hardman N, Braun R. Tubulin genes of Trypanosoma brucei: a tightly clustered family of alternating genes. Proc Natl Acad Sci U S A 1983; 80:4634-8. [PMID: 6308633 PMCID: PMC384098 DOI: 10.1073/pnas.80.15.4634] [Citation(s) in RCA: 71] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
African trypanosomes are the causative agents of many medically and economically important diseases of man and domestic animals. The cell body of these blood-dwelling protozoa is enveloped with a dense layer of pellicular microtubules, which confer both motility and mechanical stability on these cells; microtubules are also important components of the flagellum. The major structural components of the microtubuli are two related proteins, alpha- and beta-tubulin. We have analyzed the genomic organization of alpha- and beta-tubulin genes in Trypanosoma brucei. In this organism, the majority of these genes are arranged in a single, tightly packed cluster of alternating alpha- and beta-tubulin genes with a basic repeat length together of 3.6 kilobase pairs. A genomic library of T. brucei was constructed by using the phage vector A 1059, and recombinant phages carrying tubulin genes were isolated by screening the library with heterologous chicken tubulin cDNA probes. The results of restriction endonuclease and hybridization analysis of DNA isolated from recombinant phages, and subcloned fragments thereof, were compatible with the restriction maps derived from digestion and Southern blot hybridization of genomic DNA.
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29
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Landfear SM, McMahon-Pratt D, Wirth DF. Tandem arrangement of tubulin genes in the protozoan parasite Leishmania enriettii. Mol Cell Biol 1983; 3:1070-6. [PMID: 6877238 PMCID: PMC368636 DOI: 10.1128/mcb.3.6.1070-1076.1983] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The arrangement of developmentally regulated alpha- and beta-tubulin genes has been studied in the parasitic protozoan Leishmania enriettii by using Southern blot hybridization analysis. The alpha-tubulin genes occur in a tandem repeat whose monomeric unit may be represented by a 2-kilobase PstI fragment. Similarly, the beta-tubulin genes probably occur in a separate tandem repeat consisting of approximately 4-kilobase units unlinked to the alpha-tubulin repeats.
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30
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Sherman G, Rosenberry TL, Sternlicht H. Identification of lysine residues essential for microtubule assembly. Demonstration of enhanced reactivity during reductive methylation. J Biol Chem 1983. [DOI: 10.1016/s0021-9258(18)32900-4] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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31
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Cowan NJ, Dudley L. Tubulin isotypes and the multigene tubulin families. INTERNATIONAL REVIEW OF CYTOLOGY 1983; 85:147-73. [PMID: 6689318 DOI: 10.1016/s0074-7696(08)62372-4] [Citation(s) in RCA: 50] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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32
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Scherson T, Geiger B, Eshhar Z, Littauer UZ. Mapping of distinct structural domains on microtubule-associated protein 2 by monoclonal antibodies. EUROPEAN JOURNAL OF BIOCHEMISTRY 1982; 129:295-302. [PMID: 6185336 DOI: 10.1111/j.1432-1033.1982.tb07052.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Monoclonal antibodies against microtubule-associated protein 2 (MAP2) were prepared and their specificity was verified by visualization of the antigens using the antibody overlay technique and by radioimmunoassay. MAP2 was cleaved by alpha-chymotrypsin to generate a series of high-molecular-mass fragments ranging between 270 and 140 kDa. The precursor-product relationship of these fragments was suggested from the rate of their appearance and from the analysis of the tryptic peptide map of each fragment. A group of monoclonal antibodies was found to react predominantly with the intact 270-kDa MAP2 molecule and a fragment having a mass of 240 kDa and to some extent with a 215-kDa fragment. Another group of monoclonal antibodies reacted with an antigenic determinant which was located on the 270-kDa molecule as well as on fragments as small as 140 kDa. None of the two groups of monoclonal antibodies reacted with the microtubule-binding domain of MAP2. These results suggest that one group of antibodies reacts with sites located at or dependent upon a terminal 60-kDa domain(s) distal to the microtubule-binding site of MAP2. The second group of antibodies, which can still bind to smaller proteolytic products, appear to be associated with the central region of the MAP2 molecule. Indirect immunofluorescence experiments with the antibody preparations indicated that at least some of the antigenic determinants are exposed when MAP2 is associated with microtubules in the cell body and neurite outgrowths of differentiated rat brain neuroblastoma B104 cells.
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33
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Gozes I, Littauer UZ. Microtubule protein: tubulin. SCANDINAVIAN JOURNAL OF IMMUNOLOGY. SUPPLEMENT 1982; 9:299-316. [PMID: 6763768 DOI: 10.1111/j.1365-3083.1982.tb03770.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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34
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Abstract
The clear zones seen around microtubules in transverse sections of nutritive tubes vary in size depending on whether a microtubule is bordered by ribosomes or by another microtubule. We consider that such a finding is not consistent with the current view, that the clear zone is maintained by microtubule-associated material. It can, however, be accounted for by an electrostatic repulsion between the surfaces of negatively charged microtubules and between microtubules and ribosomes which are also negatively charged. The experiments presented here, involving on the one hand the addition of cationic substances to microtubules and on the other the alteration in charge of the microtubules, support this hypothesis.
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35
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Carlier MF. Guanosine-5'-triphosphate hydrolysis and tubulin polymerization. Review article. Mol Cell Biochem 1982; 47:97-113. [PMID: 6755216 DOI: 10.1007/bf00234410] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
GTP hydrolysis associated with polymerization is a distinctive feature of microtubule assembly. This reaction may be fundamentally linked to the dynamic properties of microtubules in vivo. Kinetic analysis of the connection between microtubule assembly and associated GTP hydrolysis indicates that these two events are kinetically uncoupled, GTP hydrolysis occurring after tubulin incorporation in the microtubule. As a consequence, the combination of the diffusional incorporation of GTP in microtubules at steady-state and of subsequent GTP hydrolysis results in the formation of a steady-state GTP cap at microtubule ends. The interplay between GTP and GDP at microtubule ends is examined. Inhibition by GDP of steady-state GTP hydrolysis at microtubule ends and of microtubule elongation is understood within a tight reversible binding of GDP at microtubule ends generating 'inactive' elongation sites. Nucleotides are freely exchangeable at microtubule ends. This result indicates that the nature of the nucleotide present at microtubule ends must be considered in a model for microtubule assembly. These data are pooled in order to define the general features of a model describing microtubule assembly and treadmilling in terms somewhat different from previously proposed models.
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36
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Abstract
Two equimolar beta chains can be resolved from sea urchin sperm flagellar and scallop gill ciliary tubulins, and from certain brain tubulins as well, using the Triton X-100-acid-urea polyacrylamide gel system commonly used for histone analysis. The beta chains are identified as such from their mobility on urea-free SDS PAGE, from amino acid composition, and from tryptic peptide distribution. Scallop beta chains have almost identical amino acid profiles but they differ by one tryptic peptide. Optimal conditions for beta chain resolution are very species-dependent, with some closely related species showing either maximal or no beta chain separation. In addition, beef brain tubulin on Triton X-100-acid-urea electrophoresis and scallop gill ciliary tubulin upon isoelectric focusing in the presence of SDS show two approximately equimolar alpha chains. These data, indicating equimolar amounts of two potentially different tubulin heterodimers from a variety of microtubule types, support a model for microtubule structure wherein protofilaments consist of alternating heterodimers of two kinds, generating a 16-nm (2-dimer) axial repeat.
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37
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Abstract
Confusion appears to have arisen in the literature regarding the designation of alpha- and beta-tubulin in polyacrylamide gels. The presence or absence of 8 M-urea in sodium dodecyl sulfate (SDS) polyacrylamide gels leads to different patterns for unalkylated tubulin subunits (and other proteins), making difficult the designation of the alpha and beta subunits by original definition using electrophoretic mobility in the molecular weight dimension. The specific biochemical property of posttranslational tyrosylation of the alpha subunit has been used to identify further this subunit. Under all conditions tested, the beta subunit has been found to be more acidic than the alpha subunit, with isoelectric point differences that agree with theoretical and published values. If the tubulin subunits are reduced and alkylated, the beta subunit migrates more rapidly in SDS polyacrylamide gels, with or without urea present. However, unalkylated tubulin subunits can comigrate or even reverse their relative mobility if 8 M-urea-SDS polyacrylamide gels are used for subunit separation. The results also confirm the earlier reports that the post-translational tyrosylation of protein appears exclusively restricted to alpha-tubulin and can be demonstrated in an in vivo situation. In addition, the results suggest that only the alpha 2 subunit of tubulin is tyrosylated.
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38
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Effects of reductive methylation on microtubule assembly. Evidence for an essential amino group in the alpha-chain. J Biol Chem 1982. [DOI: 10.1016/s0021-9258(18)34837-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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39
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Brunke KJ, Young EE, Buchbinder BU, Weeks DP. Coordinate regulation of the four tubulin genes of Chlamydomonas reinhardi. Nucleic Acids Res 1982; 10:1295-310. [PMID: 6280139 PMCID: PMC320526 DOI: 10.1093/nar/10.4.1295] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
During cell division and during the induction of tubulin synthesis that accompanies flagellar regeneration in Chlamydomonas reinhardi, four tubulin mRNAs of discrete molecular sizes are produced. During induction two beta tubulin mRNAs (2.47 kb and 2.34 kb) and two alpha tubulin mRNAs (2.26 kb and 2.13 kb) are synthesized in high abundance and in a closely coordinated fashion. Combined data from restriction enzyme mapping (i.e., Southern analysis) of genomic DNA and of Charon 30 recombinant clones bearing inserts of Chlamydomonas tubulin genes provide direct evidence for four distinct tubulin genes in this organism. Dot-blot analysis of the level of hybridization of a 32p nick-translated beta tubulin cDNA to genomic DNA from gametic cells and to a clone containing the beta 1 tubulin gene indicate that each beta 1 tubulin gene is present in one copy per cell. Additional hybridization experiments employing fragments of cDNA clones which selectively anneal to either the 3' or 5' portions of the two alpha tubulin genes or to one or both of the two beta tubulin genes suggest that each tubulin gene is actively transcribed to give rise to one of the four tubulin mRNAs. These observations further suggest that at most four basic types of tubulin subunits are produced by Chlamydomonas and that the heterogeneity of tubulin subunits reported to exist in the flagellar axoneme must arise as a result of post-translational modification.
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40
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Wadsworth P, Sloboda RD. Characterization of tubulin modified with the sulfhydryl-reactive fluorochrome monobromo(trimethylammonio)bimane. Biochemistry 1982; 21:21-8. [PMID: 7059577 DOI: 10.1021/bi00530a004] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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41
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Wilde CD, Chow LT, Wefald FC, Cowan NJ. Structure of two human alpha-tubulin genes. Proc Natl Acad Sci U S A 1982; 79:96-100. [PMID: 6275393 PMCID: PMC345668 DOI: 10.1073/pnas.79.1.96] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The ability of a chicken alpha-tubulin cDNA probe to cross-hybridize with human DNA under stringent conditions has been exploited to screen two independently constructed human genomic libraries. Nine clones were isolated, accounting for 60% of the bands observed in a whole genomic Southern blot of human DNA. Two clones were selected for further analysis by restriction mapping, orientation experiments using 3'- or 5'-specific probes, and electron microscopy of heteroduplexes. One clone, 2 alpha, contains an alpha-tubulin-specific region of 5.0 kilobases that includes three intervening sequences. The second clone, 19 alpha, contains an alpha-tubulin-specific region of 5.4 kilobases and has somewhat diverged 5' and 3' ends. Clone 19 alpha has only two intervening sequences that correspond to the first two in clone 2 alpha. However, these intervening sequences differ in size between clones 2 alpha and 19 alpha and show no detectable sequence homology. The sum of the lengths of sequences in either clone that hybridize to the cDNA probe accounts for essentially the entire length of the cDNA molecule.
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42
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43
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Osborn M, Weber K. Immunofluorescence and immunocytochemical procedures with affinity purified antibodies: tubulin-containing structures. Methods Cell Biol 1982; 24:97-132. [PMID: 7048022 DOI: 10.1016/s0091-679x(08)60650-0] [Citation(s) in RCA: 251] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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44
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45
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Berk B, Hinkle P. Purification of a stimulator of microtubule assembly from bovine thyroid. J Biol Chem 1981. [DOI: 10.1016/s0021-9258(19)68485-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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46
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Abstract
Microtubule polymerization in vitro is the summation of different reactions occurring at each end of the polymer. In steady-state conditions in vitro, net tubulin addition on the microtubule occurs at one end of the polymer, and net tubulin loss occurs at the opposite end. Thus, a unidirectional flux of tubulin from one end of the microtubule to the other, or "treadmilling', can occur. The opposite end assembly--disassembly behaviour of microtubules, if it occurs within cells, could be fundamentally linked to the functions of microtubules, as, for example, in the translocation of chromosomes during mitosis.
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47
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Cowan NJ, Wilde CD, Chow LT, Wefald FC. Structural variation among human beta-tubulin genes. Proc Natl Acad Sci U S A 1981; 78:4877-81. [PMID: 6946435 PMCID: PMC320280 DOI: 10.1073/pnas.78.8.4877] [Citation(s) in RCA: 49] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
A chicken beta-tubulin cDNA probe has been used to screen two independently generated human genomic libraries. Of 13 EcoRI fragments detectable in a human genomic Southern blot experiment, 7 correspond in size to EcoRI fragments isolated from recombinant bacteriophage. The location of beta-tubulin-specific regions and the direction of transcription were determined within each cloned fragment. One clone (5 beta) contained a beta-tubulin-specific region of 6.8 kilobase pairs (kbp) that included three intervening sequences as well as a number of inverted repeat structures. The remaining clones contained beta-tubulin-specific sequences that were close to or, in two cases, substantially less than 1.9 kbp long. Because mature human beta-tubulin mRNA is approximately 1.9 kbp long, these short DNA regions cannot on their own encode a functional beta-tubulin mRNA. Analysis using 3'- and 5'-specific probes derived from the chicken cDNA clone showed the presence of both of these end regions within one truncated tubulin-like sequence. A second short tubulin-specific region failed to hybridize with a 3'-specific probe. These short sequences are therefore likely to be examples of pseudogenes that have arisen by loss of a portion of DNA essential to the production of functional human beta-tubulin mRNA.
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48
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Krauhs E, Little M, Kempf T, Hofer-Warbinek R, Ade W, Ponstingl H. Complete amino acid sequence of beta-tubulin from porcine brain. Proc Natl Acad Sci U S A 1981; 78:4156-60. [PMID: 6945576 PMCID: PMC319747 DOI: 10.1073/pnas.78.7.4156] [Citation(s) in RCA: 245] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The primary structure of porcine brain beta-tubulin was determined by automated and manual Edman degradation of six sets of overlapping peptides. The protein consists of 445 amino acid residues and has a minimum of six positions that are heterogeneous, indicating at least two beta-tubulins in porcine brain. Comparison of the optimally aligned sequences of alpha-tubulin and beta-tubulin indicates that 41% of their primary structures are identical. A region rich in glycyl residues is similar both in sequence and predicted secondary structure to the phosphate binding loop of several nucleotide binding enzymes. beta-Tubulin contains a highly acidic COOH-terminal region that resembles the NH2-terminus of troponin T.
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49
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LYNN DENISH. THE ORGANIZATION AND EVOLUTION OF MICROTUBULAR ORGANELLES IN CILIATED PROTOZOA. Biol Rev Camb Philos Soc 1981. [DOI: 10.1111/j.1469-185x.1981.tb00350.x] [Citation(s) in RCA: 136] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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50
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Ponstingl H, Krauhs E, Little M, Kempf T. Complete amino acid sequence of alpha-tubulin from porcine brain. Proc Natl Acad Sci U S A 1981; 78:2757-61. [PMID: 7019911 PMCID: PMC319436 DOI: 10.1073/pnas.78.5.2757] [Citation(s) in RCA: 230] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The amino acid sequence of alpha-tubulin from porcine brain was determined by automated and manual Edman degradation of eight sets of overlapping peptides. It comprises 450 residues plus a COOH-terminal tyrosine that is present only in 15% of the material. A region of 40 residues at the COOH-terminus is highly acidic, mainly due to 16 glutamyl residues. This high concentration of negative charge suggests a region for binding cations. At least six positions, most of them around position 270, are occupied by two amino acid residues each. Several of these exchange sites were assigned to specific peptides by analysis of the purified corresponding fragments. These data indicate four alpha-tubulins in porcine brain. Although alpha-tubulin on the whole is unrelated to other proteins, there are regions that can be correlated to sequences of the myosin head, to actin, to tropomyosin, and to troponins C and T.
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