Patterns of tubulin isotype synthesis and usage during mitotic spindle morphogenesis in <i>Physarum</i>

Paul, Eileen C. A.; Roobol, Anne; Foster, Kay E.; Gull, Keith

doi:10.1002/cm.970070309

Cited by 15 publications

(5 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Since the different P-tubulins are present in the cytoskeleton and spindle preparations in a stoichiometry similar to that observed in the myxamoebal or plasmodial samples, Pl-210 tubulin seems not to be selectively enriched in either of these microtubular organelles. These results also establish that both of the P-tubulins expressed in myxamoebae are used in the cytoskeleton, and confirm that both /3-tubulin isotypes expressed in plasmodia are used in the mitotic spindle (Paul et al, 1987).…”

Section: Presence Of Pl-210 Tubulin In Dytoskeletons and Mitotic Spinsupporting

confidence: 71%

See 1 more Smart Citation

Location of a Single -Tubulin Gene Product in Both Cytoskeletal and Mitotic-spindle Microtubules in Physarum polycephalum

1989

View full text Add to dashboard Cite

In the mutant BEN210 of Physarumpolycephalum several P-tubulins are detectable. pl-tubulin is unique to the myxamoeba, P2-tubulin is unique to the plasmodium, and the mutant Pl-210 tubulin encoded by the benD210 allele is present in both cell types. In order to analyse the subcellular distribution of the Pl-2 10 polypeptide, we prepared cytoskeletons from myxamoebae and mitotic spindles from plasmodia, and examined the tubulin polypeptide composition of these microtubular organelles by two-dimensional gel electrophoresis and immunoblotting. The results show that the Pl-210 tubulin is present in microtubules of both the cytoskeleton and the intranuclear mitotic spindle. Thus a single P-tubulin gene product can participate in multiple microtubular organelles in distinct cellular compartments.

show abstract

Section: Presence Of Pl-210 Tubulin In Dytoskeletons and Mitotic Spinsupporting

confidence: 71%

“…Myxamoebae and plasmodia were prepared for this as described previously (Paul et al, 1987). Microtubules were detected with the anti-P-tubulin monoclonal antibody KMX-1 (Birkett et al, 1985).…”

Section: E T H O D Smentioning

confidence: 99%

Location of a Single -Tubulin Gene Product in Both Cytoskeletal and Mitotic-spindle Microtubules in Physarum polycephalum

1989

View full text Add to dashboard Cite

show abstract

“…However, it has heretofore not been possible to demonstrate unambiguous differences in the functional capacity associated with given isoforms in vivo (see discussions in Raft et al, 1987;and Monteiro and Cleveland, 1988). In cases where multiple isoforms are coexpressed in a cell, all of the isoforms appear to be intermingled, at least to some extent, in all of the microtubule populations in the cell (Bond et al, 1986;Lewis et al, 1987;Paul et al, 1987;Lopata and Cleveland, 1987). Similarly, the microtubule literature is replete with examples in which heterologous tubulins can be incorporated into functional microtubules in vivo: thus, bovine brain tubulin introduced by injection into cultured mammalian cells (Keith et al, 1981;Saxton et al, 1984), sea urchin embryos (Salmon et al, 1984), or Drosophila embryos (Kellog et al, 1988) is coassembled with endogenous tubulin into functional spindles and cytoplasmic microtubules.…”

mentioning

confidence: 99%

Two Drosophila beta tubulin isoforms are not functionally equivalent.

Hoyle

Raff

1990

The Journal of Cell Biology

211

179

View full text Add to dashboard Cite

Abstract. We have tested the functional capacity of different beta tubulin isoforms in vivo by expressing B3-tubulin either in place of or in addition to/32-tubulin in the male germ line of Drosophila melanogaster. The testes-specific isoform, B2, is conserved relative to major metazoan beta tubulins, while the developmentally regulated isoform,/33, is considerably divergent in sequence. B3-tubulin is normally expressed in discrete subsets of cells at specific times during development, but is not expressed in the male germ line, /~2-Tubulin is normally expressed only in the postmitotic germ cells of the testis, and is required for all microtubule-based functions in these cells. The normal functions of B2-tubulin include assembly of meiotic spindles, axonemes, and at least two classes of cytoplasmic microtubules, including those associated with the differentiating mitochondrial derivatives. A hybrid gene was constructed in which 5' sequences from the/~2 gene were joined to protein coding and 3' sequences of the ~3 gene. Drosophila transformed with the hybrid gene express B3-tubulin in the postmitotic male germ cells. When exPressed in the absence of the normal testis isoform,/$3-tubulin supports assembly of one class of functional cytoplasmic microtubules. In such males the microtubules associated with the membranes of the mitochondrial derivatives are assembled and normal mitochondrial derivative elongation occurs, but axoneme assembly and other microtubule-mediated processes, including meiosis and nuclear shaping, do not occur. These data show that 133 tubulin can support only a subset of the multiple functions normally performed by/32, and also suggest that the microtubules associated with the mitochondrial derivatives mediate their elongation. When/33 is coexpressed in the male germ line with/32, at any level, spindles and all classes of cytoplasmic microtubules are assembled and function normally. However, when/33-tubulin exceeds 20% of the total testis beta tubulin pool, it acts in a dominant way to disrupt normal axoneme assembly. In the axonemes assembled in such males, the doublet tubules acquire some of the morphological characteristics of the singlet microtubules of the central pair and accessory tubules. These data therefore unambiguously demonstrate that the Drosophila beta tubulin isoforms/~2 and/~3 are not equivalent in intrinsic functional cai~acity, and furthermore show that assembly of the doublet tubules of the axoneme imposes different constraints on beta tubulin function than does assembly of singlet microtubules.

show abstract

“…The multinucleate plasmodium of P. polycephalum is unusual among eucaryotic cells in that it uses tubulins only in the mitotic-spindle microtubules; cytoskeletal, flagellar, and centriolar microtubules are absent from this cell type, even though they are present in amoebal or flagellate cell types (9,23,27). The ,B2-tubulin isotype expressed specifically in the plasmodium thus is used exclusively in the mitotic spindle (21). It is therefore of interest to determine the sequence of 12 tubulin and to analyze its structure in the context of the structures of other 13 tubulins.…”

mentioning

confidence: 99%

A gene encoding the major beta tubulin of the mitotic spindle in Physarum polycephalum plasmodia.

Burland¹,

Paul²,

Oetliker³

et al. 1988

Mol. Cell. Biol.

View full text Add to dashboard Cite

The multinucleate plasmodium of Physarum polycephalum is unusual among eucaryotic cells in that it uses tubulins only in mitotic-spindle microtubules; cytoskeletal, flagellar, and centriolar microtubules are absent in this cell type. We have identified a 1-tubulin cDNA clone, 13105, which is shown to correspond to the trnscript of the beiC P-tubulin locus and to encode 12 tubulin, the 1 tubulin expressed specifically in the plasmodium and used exclusively in the mitotic spindle. Physarum amoebae utilize tubulins in the cytoskeleton, centrioles, and flagella, in addition to the mitotic spindle. Sequence analysis shows that (2 tubulin is only 83% identical to the two ,3 tubulins expressed in amoebae. This compares with 70 to 83% identity between Physarum P12 tubulin and the 1 tubulins of yeasts, fungi, alga, trypanosome, fruit fly, chicken, and mouse. On the other hand, Physarum 12 tubulin is no more similar to, for example, Aspergillus 1 tubulins than it is to those of Drosophila melanogaster or mammals. Several eucaryotes express at least one widely diverged 1 tubulin as well as one or more 1 tubulins that conform more closely to a consensus 1-tubulin sequence. We suggest that ,B-tubulins diverge more when their expression pattern is restricted, especially when this restriction results in their use in fewer functions. This divergence among P tubulins could have resulted through neutral drift. For example, exclusive use of Physarum P2 tubulin in the spindle may have allowed more amino acid substitutions than would be functionally tolerable in the 1 tubulins that are utilized in multiple microtubular organelles.Alternatively, restricted use of P tubulins may allow positive selection to operate more freely to refine 3-tubulin function.Most eucaryotes express multiple genes each for a and K tubulins, the principal protein components of microtubules. The products of these genes usually have distinct sequences. For 13 tubulins, identity between multiple polypeptides within a single organism varies from 100% for Chlamydomonas reinhardtii (38) to 78% for mammals (34). The varied functions of microtubules in the cytoskeleton, centrioles, spindles, and flagella, together with the observed tubulin sequence differences, have inspired the conclusion that the sequence differences between multiple tubulins within an organism have been positively selected during evolution (32). The murine i tubulin M,1l is only 78% identical to several other murine i tubulins and is expressed specifically in hematopoietic tissues, prompting the speculation that at least some of the sequence differences reflect functional specialization of individual 1 tubulins (34).In the myxomycete Physarum polycephalum, threetubulin genes are known; one gene is expressed specifically in the amoebal cell type, another gene is expressed specifically in the plasmodial cell type, and the third gene, betB, is expressed in both amoebae and plasmodia (4, 28). The multinucleate plasmodium of P. polycephalum is unusual among eucaryotic cells in that it uses tubulins o...

show abstract

Patterns of tubulin isotype synthesis and usage during mitotic spindle morphogenesis in Physarum

Cited by 15 publications

References 34 publications

Location of a Single -Tubulin Gene Product in Both Cytoskeletal and Mitotic-spindle Microtubules in Physarum polycephalum

Location of a Single -Tubulin Gene Product in Both Cytoskeletal and Mitotic-spindle Microtubules in Physarum polycephalum

Two Drosophila beta tubulin isoforms are not functionally equivalent.

A gene encoding the major beta tubulin of the mitotic spindle in Physarum polycephalum plasmodia.

Contact Info

Product

Resources

About