S63-RNase is a novel non-functional S-RNase induced by phosphate starvation in Nicotiana

HERNÁN J. ROJAS AND ARIEL GOLDRAIJ

Potrero de los Funes

Congreso; SAIB Sociedad Argentina de Investigacion en Bioquimica y Biologia Molecular; 2011

SAIB

T2 ribonucleases (RNases) are secretory enzymes that catalyze the cleavage of single-strand RNA. In plants T2 RNases have different structural traits and biological roles and were classified in two subfamilies, a) S-RNases, involved in pollen recognition and rejection in plants with S-RNase-based self-incompatibility (SI) system and b) S-like-RNases, widely distributed in the plant kingdom and generally involved in the response to different biotic and abiotic stress scenarios. We have cloned a style cDNA from Nicotiana alata that exhibited the typical sequence features of an S-RNase gene, but it was non-functional in the SI system and therefore, it was denoted as non-functional S63-RNase. Surprisingly, this gene was induced when plants were hydroponically grown without Pi, a typical response of the S-like-RNases, but not reported yet in S-RNases or non-functional S-RNases. The induction was detected 7 days after Pi deprivation and increased until day 22, roughly paralleling the induction of a well-characterized S-like-RNase of Nicotiana alata. A 15 amino acid peptide of S63-RNase was used to develop a rabbit antibody. The antibody recognized a protein of ~31 kDa in crude extracts of roots coming from plants grown under Pi starvation conditions only. We are now identifying the 31 kDa protein. So far, no function has been previously assigned to non-S-RNases.