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  • hydrophobic areas  (2)
  • Evolution  (1)
  • maytansine  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 19 (1982), S. 80-86 
    ISSN: 1432-1432
    Keywords: Microtubules ; Tubulin ; Evolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tubulin subunits have been isolated from a variety of protists and marine invertebrates. The sources were: sperm tails of a tunicate (Ciona intestinalis), an abalone (Haliotis rufescens) and a sea anemone (Tealia crassicornis), the gill cilia of a clam (Mercenaria mercenaria), the cilia of a ciliate (Tetrahymena pyriformis) and the cytoplasm of a slime mold (Physarum polycephalum). All the β-tubulins, as characterised by their electropherograms after limited proteolytic cleavage withStaphylococcus aureus protease, were fairly similar. In contrast, two markedly different peptide patterns were found for the α-tubulins of (a) metazoan axonemes and (b) protistan axonemes, plant axonemes and slime mold cytoplasm. Metazoan axonemal α-tubulin peptide patterns could be further divided into two similar but distinct subtypes which did not correlate with the taxonomic divisions of deuterostomia and protostomia, or to different tubulins within an axoneme, or to different tubulins of flagella and cilia. We have postulated that these small differences may be accounted for by a simple glutamicaspartic acid exchange at a particular position in the α-tubulin sequence. Identical peptide patterns were observed for sea urchin and sea anemone sperm tail tubulins, proving that the metazoan type of axonemal tubulin arose before the divergence of bilateral and radial symmetric organisms. The close similarity of the slime mold cytoplasmic α-tubulin peptide pattern to protistan and plant axonemal α-tubulin patterns suggests that the same type of tubulin might be used to form both axonemal and cytoplasmic types of microtubules in protists and plants. The large structural constraints imposed upon this tubulin molecule probably allowed very little change in its primary structure, thus explaining the similarity of tubulins from organisms which diverged at such an early time in eukaryote history. Duplication and modification of the tubulin gene may then have led to the development of specific axonemal and cytoplasmic microtubules during the evolution of the metazoa.
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    The protein journal 16 (1997), S. 99-105 
    ISSN: 1573-4943
    Keywords: Tubulin ; phomopsin A ; alkylation ; hydrophobic areas ; C-terminal domain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Tubulin, the major component of microtubules, has a tendency to lose its ability to assemble or to bind to ligands in a time-dependent process known as “decay.” The decay process also causes tubulin to expose sulfhydryl groups and hydrophobic areas. The antimitotic drug phomopsin A strongly protects the tubulin molecule from decay. Here we have studied the interaction of phomopsin A with αβ tubulin and tubulin which has been treated with subtilisin to remove selectively the C-termini of the α and β chains (αsβs). The binding of phomopsin A to αβ tubulin decreases the sulfhydryl titer by approximately 1.0 mol/mol. Selective removal of the peptides from the C-terminal ends does not affect phomopsin A's interaction with tubulin. Moreover, the αsβs tubulin–phomopsin A complex appears to be more stable than the αβ tubulin–phomopsin A complex as determined by the time-dependent increase in exposure of sulfhydryl groups and hydrophobic areas on tubulin. In fact, phomopsin A inhibits the decay process of αsβs tubulin completely. This observation raises the possibility of determining the conformtion of this configuration of tubulin.
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  • 3
    ISSN: 1573-4943
    Keywords: Vinblastine ; tubulin ; microtubule-associated proteins ; tau ; maytansine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Microtubule-associated proteins (MAPs) can promote microtubule assemblyin vitro. One of these MAPs (MAP2) consists of a short promoter domain which binds to the microtubule and promotes assembly and a long projection domain which projects out from the microtubule and may interact wth other cytoskeletal elements. We have previously shown that MAP2 and another MAP, tau, differ in their interactions with tubulin in that tau, but not MAP2, promotes extensive aggregation of tubulin into spiral clusters in the presence of vinblastine and that microtubules formed with MAP2 are more resistant than those formed with tau to the antimitotic drug maytansine [Luduena, R. F.,et al. (1984),J. Biol. Chem. 259, 12890–12898; Fellous, A.,et al. (1985),Cancer Res. 45, 5004–5010]. Here we have used chymotryptic digestion to remove the projection domain of MAP2 and examined the interaction of the digested MAP2 (ctMAP2) with tubulin in the presence of vinblastine and maytansine. We have found that ctMAP2 behaves very much like tau, but not like undigested MAP2, in the presence of vinblastine, in that ctMAP2 causes tubulin to polymerize into large clusters of spirals. In contrast, microtubule assembly in the presence of ctMAP2 is much more resistant to maytansine inhibition than is assembly in the presence of tau or undigested MAP2. Our results suggest that the projection domain of MAP2 may play a role in the interaction of tubulin with MAP2 during microtubule assembly.
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  • 4
    ISSN: 1573-4943
    Keywords: Tubulin ; IKP104 ; alkylation ; hydrophobic areas ; C-terminal domain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract IKP104, a novel antimitotic drug, has two classes of binding sites on bovine brain tubulin with different affinities. IKP104, by itself, enhances the decay of tubulin, but in the presence of colchicine or podophyllotoxin, it stabilizes tubulin instead of opening up the hydrophobic areas [Luduena et al. (1995), Biochemistry 34, 15751–15759], Here, we have dissected these two apparently contradictory effects of IKP104 by cleaving the C-terminal ends of both α and β subunits of tubulin with subtilisin. We have found that the selective removal of the C-terminal ends from both the α and β subunits of αβ tubulin lowers the sulfhydryl titer by approximately 1.5 mol/mol of dimer. Interestingly, IKP104 does not increase either the sulfhydryl liter or the exposure of hydrophobic areas of this subtilisin-treated tubulin (αsβs). Moreover, IKP104 lowers the sulfhydryl titer of αsβs tubulin approximately by 1 mol/mol and appears to inhibit completely the time-dependent decay of αsβs tubulin. The cleavage at the C-terminal ends of both α and β modulates the effect of IKP104 on the β subunit, but not on the α subunit. Fluorometric binding data analysis suggests that IKP104 binds to the αsβs tubulin only at the high-affinity site; the low-affinity site(s) disappear almost completely. The sulfhydryl titer data for α and β and the fluoromelric data therefore suggest that the interaction of IKP104 at the high-affinity site on tubulin is not regulated by the C-terminal domains of α and β and the effect of the high-affinity site is restricted largely to the α subunit, while the low-affinity-site binding is modulated by the C-terminal domain of β. It also appears that the stabilization and the acceleration of the decay of tubulin are mediated by distinct interactions of IKP104 with its high- and low-affinity sites on tubulin, respectively.
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