The α‐ and β‐Tubulin Genes of Euplotes octocarinatus

Abstract

The alpha- and the beta-tubulin genes of the hypotrichous ciliate Euplotes octocarinatus were isolated from a size-selected macronuclear DNA library. The alpha-tubulin gene is located on a 1,587 bp macronuclear DNA molecule and the beta-tubulin gene on a 1,524 bp macronuclear DNA molecule. Sequencing revealed that all the cysteine residues of the two genes are encoded by the common cysteine codons UGU and UGC and none by an UGA codon. This is in contrast to the genes of E. octocarinatus sequenced so far, where some of the cysteines are encoded by the opal codon UGA. The tubulin genes end like other Euplotes genes with a TAA. They do not contain introns. The last codon for an amino acid in the alpha-tubulin gene is a GAA which codes for glutamic acid. This is in contrast to what has been reported for most alpha-tubulin genes, but it supports for other hypotrichous ciliates. No evidence for the existence of more than one type of alpha- and one type of beta-tubulin genes could be obtained.

Cold-adapted microtubules: Characterization of tubulin posttranslational modifications in the Antarctic ciliateEuplotes focardii

“…Alignment of some protozoan and vertebrate amino acid sequences of the ␤-tubulin COOH-domain. The ␤-T1 and ␤-T3 sequences of E. focardii are aligned with the ␤-tubulin sequences of the ciliates E. octocarinatus [Liang et al, 1994], E. crassus [Harper and Jahn, 1989], Tetrahymena pyriformis [Barahona et al, 1988], which is fully identical to the ␤-tubulin sequence of T. thermophila [Gaertig et al, 1993], and Paramecium tetraurelia [Dupuis, 1992] and with the sequences of the vertebrate ␤-tubulin isotypes (classes III and IV) [Sullivan and Cleveland, 1986] that show the highest similarity with protozoan ␤-tubulin. The ␤-tubulin sequence of the Antarctic fish Notothenia coriiceps neglecta [Detrich and Parker, 1993] is also included, being the only other known tubulin sequence of a poikilotherm organism.…”

Expression of a MORN repeat protein from Euplotes octocarinatus requires a +1 programmed ribosomal frameshifting

“…The genetic apparatus of E .octocarinatus consists, like in other ciliates, of two types of nuclei: the transcriptionally quiescent micronucleus and the transcriptionally active macronucleus. 12) It has generally been confirmed that in Euplotes, UGA is translated as cysteine 13) or selenocysteine, 14) and using UAA and UAG as the termination codon. In addition, a number of genes from Euplotes have been identified that appear to require a +1 PRF to produce their protein products.…”

Klaus Heckmann (1934–2012)

“…Liang and Heckmann () reported the first characterization of a γ‐tubulin‐encoding gene in a ciliate, which differed in some important respects from the α‐ and β‐tubulin genes that they analyzed in the same organism (Liang et al. ). Working in collaboration with French researchers from Gif‐sur‐Yvette and Toulouse, they then demonstrated the localization of γ‐tubulin in basal bodies (Liang et al.…”