A Tetrahymena orthologue of the mouse chaperonin subunit CCT gamma and its coexpression with tubulin during cilia recovery.

A Tetrahymena pyriformis gene orthologue to the mouse CCT gamma gene has been cloned and sequenced. The coding region of this gene, named TpCCT gamma, is interrupted by six introns and codes for a protein of 559 amino acid residues. This protein shares a 57.6% identity with the mouse CCT gamma protein whereas in average a 30% identity was found with CCT alpha proteins from mammalian to yeast. The expression of this gene was investigated by Northern blot hybridization in Tetrahymena exponentially growing cells and cells during cilia recovery. The TpCCT gamma gene is expressed producing a unique transcript of 2.1 kilobases. A relevant aspect of our findings is the coordinated response of TpCCT gamma and tubulin genes to cilia regeneration. TpCCT gamma and tubulin transcripts reached higher levels between 45-120 min of reciliation compared to those found in exponentially growing cells. These high levels could be the result of the increase in apparent transcription rates detected at 60 min of reciliation. We also observed that TpCCT gamma transcripts are not increased after exposure of Tetrahymena cells to a heat-shock (28-->34 degrees C). Our results seem to indicate an important role of this gene in the differentiation process of ciliogenesis.