Molecular cloning and characterization of a cDNA encoding endonuclease from potato (Solanum tuberosum)

A cDNA, StEN1, encoding a potato (Solanum tuberosum) endonuclease was cloned and sequenced. The nucleotide sequence of this clone contains an open reading frame of 906 nucleotides encoding a protein of 302 amino acids, and with a calculated molecular mass of 34.4 kDa and a Pi of 5.6. The deduced StEN1 protein contains a putative signal sequence of 25 amino acid residues. The StEN1 encoded protein shows substantial homology to both plant and fungal endonucleases isolated and cloned from other sources. The highest identity (73%) was observed with AgCEL I from celery, Apium graveolens, ZEN1 from Zinnia elegans (69%) and DSA6 from daylily, Hemerocallis (68%). RT-PCR expression analysis demonstrated that the potato StEN1 gene is constitutively expressed in potato, although minor differences in expression level in different tissues were observed.