Selective Regulation of Autophagy by the Iml1p-Npr2p-Npr3p Complex in the Absence of Nitrogen Starvation.

Autophagy is an evolutionarily conserved pathway for the degradation of intracellular contents. How autophagy is regulated, especially upon changes in metabolic and nutritional state, remains poorly understood. By using a prototrophic strain of Saccharomyces cerevisiae, we observed that unexpectedly, autophagy is strongly induced simply upon switch from a rich medium ...
to a minimal medium in the complete absence of nitrogen starvation. This novel form of autophagy was termed non-nitrogen-starvation (NNS)-induced autophagy. A visual screen uncovered three regulators of autophagy, Iml1p, Npr2p and Npr3p, which function in the same complex and are selectively required for NNS-induced autophagy. During NNS-induced autophagy, Iml1p localized to either pre-autophagosomal structures (PAS) or non-PAS punctate structures, which suggests that Iml1p or the Iml1p-Npr2p-Npr3p complex might regulate autophagosome formation. Ultra-structural analysis confirmed that autophagosome formation was strongly impaired in Δiml1, Δnpr2 and Δnpr3 cells during NNS-induced autophagy. Moreover, Iml1p contains a conserved domain that is required for NNS-induced autophagy as well as complex formation. Collectively, our findings have revealed the existence of additional mechanisms that regulate autophagy under previously unrecognized conditions, in response to relatively more subtle changes in metabolic and nutritional state.
Unknown
Date: Sep. 07, 2011
Download Curated Data For This Publication
124600
Switch View:
  • Interactions 6