The water-borne protein signals (pheromones) of the Antarctic ciliated protozoan, Euplotes nobilii: structure of the gene coding for the En-6 pheromone

• Published in: Canadian Journal of Microbiology
• Main Authors: LA TERZA, Antonietta, DOBRI, NICOLETA, ALIMENTI, Claudio, VALLESI, Adriana, LUPORINI, Pierangelo
• Other Authors: Dobri, Nicoleta, Alimenti, Claudio, Vallesi, Adriana, Luporini, Pierangelo
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2009
• Subjects: Antarctic; The Antarctic; Antarc*
• Online Access: http://hdl.handle.net/11581/115119; https://doi.org/10.1139/W08-122

The marine Antarctic ciliate, Euplotes nobilii, secretes a family of water-borne signal proteins, denoted as pheromones, that control the cell vegetative proliferation and mating. Based on the knowledge of the amino acid sequences of a set of these pheromones isolated from the culture supernatant of wild-type strains, we designed probes to identify their encoding genes represented by linear sub-chromosomic (gene-sized) DNA molecules in the somatic nucleus (macronucleus) of the cell. The full-length gene of the pheromone En-6 was determined and found to contain an open reading frame specific for the synthesis of the En-6 cytoplasmic precursor (pre-pro-En-6), that requires two proteolytic cleavages to remove the signal-peptide (pre) and the pro segment before secretion of the mature protein. In contrast to from the sequence variability that distinguishes the secreted pheromones, the pre and pro sequences appear to be tightly conserved and useful to construct probes to clone every other E. nobilii pheromone gene. Potential intron sequences in the coding region of the En-6 gene imply the synthesis of more En-6 isoforms.