Structure and arrangement of the beta-tubulin genes of Leishmania tropica

1984 ◽  
Vol 4 (7) ◽  
pp. 1372-1383
Author(s):  
P L Huang ◽  
B E Roberts ◽  
D M Pratt ◽  
J R David ◽  
J S Miller
Keyword(s):  
Protozoan Parasite ◽  
Leishmania Tropica ◽  
Beta Tubulin ◽  
S1 Nuclease ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Repeat Units ◽  
Genes Encoding ◽  
Tubulin Mrna ◽  
Parasite Leishmania

We studied the organization and arrangement of the genes encoding beta-tubulin in the protozoan parasite Leishmania tropica and examined the structure and orientation of the beta-tubulin mRNA relative to the gene. There were found to be eight to nine beta-tubulin genes arranged in an array of direct tandem repeat units with a length of 3.8 kilobase pairs, and they were extremely homologous, if not identical, in sequence. These repeat units did not contain the alpha-tubulin genes. The transcribed sequences within the beta-tubulin genes were localized, and the orientation of the major alpha-tubulin mRNA was mapped on the gene by S1 nuclease analysis.

scholarly journals Structure and arrangement of the beta-tubulin genes of Leishmania tropica.

1984 ◽  
Vol 4 (7) ◽  
pp. 1372-1383 ◽  
Author(s):  
P L Huang ◽  
B E Roberts ◽  
D M Pratt ◽  
J R David ◽  
J S Miller
Keyword(s):  
Protozoan Parasite ◽  
Leishmania Tropica ◽  
Beta Tubulin ◽  
S1 Nuclease ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Repeat Units ◽  
Genes Encoding ◽  
Tubulin Mrna ◽  
Parasite Leishmania

We studied the organization and arrangement of the genes encoding beta-tubulin in the protozoan parasite Leishmania tropica and examined the structure and orientation of the beta-tubulin mRNA relative to the gene. There were found to be eight to nine beta-tubulin genes arranged in an array of direct tandem repeat units with a length of 3.8 kilobase pairs, and they were extremely homologous, if not identical, in sequence. These repeat units did not contain the alpha-tubulin genes. The transcribed sequences within the beta-tubulin genes were localized, and the orientation of the major alpha-tubulin mRNA was mapped on the gene by S1 nuclease analysis.

Tandem arrangement of tubulin genes in the protozoan parasite Leishmania enriettii

1983 ◽  
Vol 3 (6) ◽  
pp. 1070-1076
Author(s):  
S M Landfear ◽  
D McMahon-Pratt ◽  
D F Wirth
Keyword(s):  
Tandem Repeat ◽  
Blot Hybridization ◽  
Protozoan Parasite ◽  
Southern Blot Hybridization ◽  
Beta Tubulin ◽  
Developmentally Regulated ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Southern Blot Hybridization Analysis ◽  
Leishmania Enriettii

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.

scholarly journals Tandem arrangement of tubulin genes in the protozoan parasite Leishmania enriettii.

1983 ◽  
Vol 3 (6) ◽  
pp. 1070-1076 ◽  
Author(s):  
S M Landfear ◽  
D McMahon-Pratt ◽  
D F Wirth
Keyword(s):  
Tandem Repeat ◽  
Blot Hybridization ◽  
Protozoan Parasite ◽  
Southern Blot Hybridization ◽  
Beta Tubulin ◽  
Developmentally Regulated ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Southern Blot Hybridization Analysis ◽  
Leishmania Enriettii

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.

Transcriptional regulation of tubulin gene expression in differentiating trochoblasts during early development of Patella vulgata

Development ◽  
1994 ◽  
Vol 120 (10) ◽  
pp. 2835-2845
Author(s):  
W.G. Damen ◽  
L.A. van Grunsven ◽  
A.E. van Loon
Keyword(s):  
Gene Expression ◽  
Gene Product ◽  
Cell Lines ◽  
Upstream Region ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Cell Stage ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Tubulin Mrna

The expression of alpha- and beta-tubulin genes during the early development of the marine mollusk Patella vulgata has been investigated. From the 32-cell stage onwards, an enhanced expression of both alpha- and beta-tubulin mRNAs was detected in the primary trochoblasts. After one additional cleavage, these cells become cleavage-arrested and then form cilia. They are the first cells to differentiate during Patella development. Later, alpha- and beta-tubulin mRNA is also found in the accessory and secondary trochoblasts. Together these three cell-lines form the prototroch, the ciliated locomotory organ of the trochophore larva. The early and abundant expression of tubulin genes precede and accompany cilia formation in the trochoblasts and provides us with an excellent molecular differentiation marker for these cells. Apart from the trochoblasts, tubulin gene expression was also found in other cells at some stages. At the 88-cell stage, elevated tubulin mRNA levels were found around the large nucleus of the mesodermal stem cell 4d. In later stages, tubulin gene expression was detected in the cells that form the flagella of the apical tuft and in the refractive bodies. An alpha-tubulin gene was isolated and characterized. A lacZ fusion gene under control of the 5′ upstream region of this tubulin gene was microinjected into embryos at the two-cell stage. The reporter gene product was only detected in the three trochoblast cell-lines at the same time as tubulin genes were expressed in these cells. Reporter gene product was not detected in any other cells. Thus, this 5′ upstream region of this alpha-tubulin gene contains all the elements required for the correct spatiotemporal pattern of expression.

scholarly journals Gene-specific signal transduction between microtubules and tubulin genes in Tetrahymena thermophila.

1995 ◽  
Vol 15 (9) ◽  
pp. 5173-5179 ◽  
Author(s):  
L Gu ◽  
J Gaertig ◽  
L A Stargell ◽  
M A Gorovsky
Keyword(s):  
Gene Expression ◽  
Signal Transduction ◽  
Mammalian Cells ◽  
Tetrahymena Thermophila ◽  
Tubulin Gene ◽  
Beta Tubulin ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Cell Biol ◽  
Tubulin Mrna

Mammalian cells regulate tubulin mRNA abundance by a posttranscriptional mechanism dependent on the concentration of tubulin monomer. Treatment of mammalian cells with microtubule-depolymerizing drugs and microtubule-polymerizing drugs causes decreases and increases in tubulin mRNA, respectively (D. W. Cleveland, Curr. Opin. Cell Biol. 1:10-14, 1989). In striking contrast to the case with mammalian cells, perturbation of microtubules in Tetrahymena thermophila by microtubule-depolymerizing or -polymerizing drugs increases the level of the single alpha-tubulin gene message by increasing transcription (L. A. Stargell, D. P. Heruth, J. Gaertig, and M. A. Gorovsky, Mol. Cell. Biol. 12:1443-1450, 1992). In this report we show that antimicrotubule drugs preferentially induce the expression of one of two beta-tubulin genes (BTU1) in T. thermophila. In contrast, deciliation induces expression of both beta-tubulin genes. Tubulin gene expression was examined in a mutant strain created by transformation with an in vitro-mutagenized beta-tubulin gene that conferred resistance to microtubule-depolymerizing drugs and sensitivity to the polymerizing drug taxol and in a strain containing a nitrosoguanidine-induced mutation in the single alpha-tubulin gene that conferred the same pattern of drug sensitivities. In both cases the levels of tubulin mRNA expression from the drug-inducible BTU1 gene in the mutant cells paralleled the altered growth sensitivities to microtubule drugs. These studies demonstrate that T. thermophila has distinct, gene-specific mechanisms for modulating tubulin gene expression depending on whether ciliary or cytoplasmic microtubules are involved. They also show that the cytoplasmic microtubule cytoskeleton itself participates in a signal transduction pathway that regulates specific tubulin gene transcription in T. thermophila.

Dominant effects of tubulin overexpression in Saccharomyces cerevisiae

1989 ◽  
Vol 9 (3) ◽  
pp. 1049-1059
Author(s):  
D Burke ◽  
P Gasdaska ◽  
L Hartwell
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Chromosome Loss ◽  
Beta Tubulin ◽  
Alpha Tubulin ◽  
Inducible Promoters ◽  
Selective Degradation ◽  
Novel Structure ◽  
Genes Encoding ◽  
Transient Overexpression ◽  
Mutant Phenotypes

The consequences of altering the levels of alpha- and beta-tubulin in Saccharomyces cerevisiae were examined by constructing fusions of the structural genes encoding the tubulins to strong galactose-inducible promoters. Overexpression of beta-tubulin (TUB2) was lethal: cells arrested in the G2 stage of the cell cycle exhibited an increased frequency of chromosome loss, were devoid of microtubules, and accumulated beta-tubulin in a novel structure. Overexpression of the major alpha-tubulin gene (TUB1) was not lethal and did not affect chromosome segregation. The rate of alpha-tubulin mRNA and protein synthesis was increased, but the protein did not accumulate. Overexpression of both alpha- and beta-tubulin together resulted in arrested cell division, and cells accumulated excess tubules that contained both alpha- and beta-tubulin. Transient overexpression of both tubulins resulted in a high frequency of chromosome loss. These data suggest that strong selective pressure exists to prevent excess accumulation of microtubules or beta-tubulin and suggest a model by which this goal may be achieved by selective degradation of unassembled alpha-tubulin. Furthermore, the phenotype of beta-tubulin overexpression is similar to the phenotype of a beta-tubulin deficiency. These results add to a number of recent studies demonstrating that mutant phenotypes generated by overexpression can be informative about the function of the gene product.

Phenotypic consequences of tubulin overproduction in Saccharomyces cerevisiae: differences between alpha-tubulin and beta-tubulin

1990 ◽  
Vol 10 (10) ◽  
pp. 5295-5304
Author(s):  
B Weinstein ◽  
F Solomon
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Division ◽  
Microtubule Assembly ◽  
Beta Tubulin ◽  
Alpha Tubulin ◽  
Tubulin Genes ◽  
Data Support ◽  
Cell Biol

Overexpression of alpha- and beta-tubulin genes in Saccharomyces cerevisiae, separately or together, leads to accumulation of large excesses of each of the polypeptides and arrest of cell division. However, other consequences of overexpression of these genes differ in several ways. As shown previously (D. Burke, P. Gasdaska, and L. Hartwell, Mol. Cell. Biol. 9:1049-1059, 1989), overexpression of beta-tubulin leads, at early times, to loss of microtubule structures and loss of viability. Eventually, the excess beta-tubulin forms abnormal structures. We show here that, in contrast, overexpression of alpha-tubulin led to none of these phenotypes and in fact could suppress each of the phenotypes associated with beta-tubulin accumulation. Truncated forms of beta-tubulin that were not competent to carry out microtubule functions also failed to elicit the beta-tubulin-specific phenotypes when overexpressed. The data support the hypothesis that beta-tubulin in excess over alpha-tubulin is uniquely toxic, perhaps because it interferes with normal microtubule assembly.

scholarly journals Functional analysis of the murine T lymphocyte immune response to a protozoan parasite, Leishmania tropica

1983 ◽  
Vol 78 (1) ◽  
pp. 105-120 ◽  
Author(s):  
H. D. Engers ◽  
S. G. Coutinho ◽  
G. M. C. de Araújo Lima ◽  
J. A. Louis
Keyword(s):  
T Cell ◽  
Protozoan Parasite ◽  
Delayed Type Hypersensitivity ◽  
Cell Populations ◽  
Leishmania Tropica ◽  
Intracellular Parasites ◽  
Helper Activity ◽  
Cellular Immune ◽  
Parasite Leishmania

The results presented in this review summarize a seirs of experiments designed to characterize the murine T cell imune response to the protozoan parasite Leishmania tropica. Enriched T cell populations and T cell clones specific for L. tropica antigens were derived from lymph nodes of primed mice and maintained in continous culture in vitro. These T lymphocytes were shown (A) to express the Lyt 1+ 3- cell surface phenotype, (B) to proliferate specifically in vitro in response to parasite antigens, together with a source of irradiated syngeneic macrophages, (C) to transfer antigen-specific delayed-type hypersensitivity (DTH) responses to normal syngeneic mice, (D) to induce specific activation of parasitized macrophages in vitro resulting in the destruction of intracellular parasites, (E) to provide specific helper activity for antibody responses in vitro in a hapten-carrier system. Protection studies using these defiened T cell populations should allow the characterization of parasite antigen(s) implicated in the induction of cellular immune responses beneficial for the host.

scholarly journals An amino-terminal tetrapeptide specifies cotranslational degradation of beta-tubulin but not alpha-tubulin mRNAs.

1994 ◽  
Vol 14 (6) ◽  
pp. 4076-4086 ◽  
Author(s):  
C J Bachurski ◽  
N G Theodorakis ◽  
R M Coulson ◽  
D W Cleveland
Keyword(s):  
Degradation Mechanism ◽  
Full Range ◽  
Mrna Degradation ◽  
Mrna Levels ◽  
Wild Type ◽  
Beta Tubulin ◽  
Alpha Tubulin ◽  
Amino Terminal ◽  
Tubulin Subunit ◽  
Tubulin Mrna

The steady-state level of alpha- and beta-tubulin synthesis is autoregulated by a posttranscriptional mechanism that selectively alters alpha- and beta-tubulin mRNA levels in response to changes in the unassembled tubulin subunit concentration. For beta-tubulin mRNAs, previous efforts have shown that this is the result of a selective mRNA degradation mechanism which involves cotranslational recognition of the nascent amino-terminal beta-tubulin tetrapeptide as it emerges from the ribosome. Site-directed mutagenesis is now used to determine that the minimal sequence requirement for conferring the full range of beta-tubulin autoregulation is the amino-terminal tetrapeptide MR(E/D)I. Although tubulin-dependent changes in alpha-tubulin mRNA levels are shown to result from changes in cytoplasmic mRNA stability, transfection of wild-type and mutated alpha-tubulin genes reveals that alpha- and beta-tubulin mRNA degradation is not mediated through a common pathway. Not only does the amino-terminal alpha-tubulin tetrapeptide MREC fail to confer regulated mRNA degradation, neither wild-type alpha-tubulin transgenes nor an alpha-tubulin gene mutated to encode an amino-terminal MREI yields mRNAs that are autoregulated. Further, although slowing ribosome transit accelerates the autoregulated degradation of endogenous alpha- and beta-tubulin mRNAs, degradation of alpha-tubulin transgene mRNAs is not enhanced, and in one case, the mRNA is actually stabilized. We conclude that, despite similarities, alpha- and beta-tubulin mRNA destabilization pathways utilize divergent determinants to link RNA instability to tubulin subunit concentrations.

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