The SM19 gene, required for duplication of basal bodies in Paramecium, encodes a novel tubulin, eta-tubulin.
The discovery of delta-tubulin, the fourth member of the tubulin superfamily, in Chlamydomonas [1] has led to the identification in the genomes of vertebrates and protozoa of putative delta homologues and of additional tubulins, epsilon and zeta [2-4]. These discoveries raise questions concerning the functions of these novel tubulins, their interactions with microtubule arrays and microtubule-organising centres, and their evolutionary status. The sm19-1 mutation of Paramecium specifically inhibits basal body duplication [5] and causes delocalisation of gamma-tubulin, which is also required for basal body duplication [6]. We have cloned the SM19 gene by functional complementation and found that it encodes another new member of the tubulin superfamily. SM19p, provisionally called eta-tubulin (eta-tubulin), shows low sequence identity with the tubulins previously identified in Paramecium, namely, alpha [7], beta [8], gamma [6], delta (this work) and epsilon (P. Dupuis-Williams, personal communication). Phylogenetic analysis indicated that SM19p is not consistently grouped with any phylogenetic entity.
Ruiz
F
F
Centre de Génétique Moléculaire du C.N.R.S., Allée de la Terrasse, 91190, Gif-sur-Yvette, France. ruiz@cgm.cnrs-gif.fr
Krzywicka
A
A
Klotz
C
C
Keller
A
A
Cohen
J
J
Koll
F
F
Balavoine
G
G
Beisson
J
J
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D017125:Genes, Protozoan / Q000502:physiology*; D006801:Humans; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010247:Paramecium / Q000235:genetics / Q000502:physiology*; D010802:Phylogeny; D015800:Protozoan Proteins / Q000145:classification / Q000235:genetics*; D017386:Sequence Homology, Amino Acid; D014404:Tubulin / Q000145:classification / Q000235:genetics*
D018076:DNA, Complementary; D015800:Protozoan Proteins; D014404:Tubulin