Functional diversity of potato SNF1-related kinases tested in Saccharomyces cerevisiae

Sucrose nonfermenting 1 catalytic subunit (SNF1)-type protein kinases are members of a metabolite-sensing protein kinase family distributed ubiquitously from yeast to plants and animals. In yeast cells, SNF1 acts in complex with the activator subunit SNF4 and a member of the SIP1/SIP2/GAL83 family responsible for substrate definition. The potato (Solanum tuberosum) genome possesses at least two SnRK1s, designated PKIN1 and StubSNF1. In this study, potato kinase 1 (PKIN1) and StubSNF1 were analysed in the yeast two-hybrid system and characterised by suppression of yeast mutations. It was shown that StubSNF1 interacted with the GAL83 ortholog of potato, StubGAL83, and complemented the Delta snf1 mutation. Moreover, it suppressed Delta snf4 and Delta sip1,Delta sip2,Delta gal83 deficiencies. In contrast, PKIN1 was unable to interact with StubGAL83 and did not rescue the yeast mutants. These data suggest different functions for PKIN1 and StubSNF1 in potato.