GAPR-1 Interferes with Condensate Formation of Beclin 1 in Saccharomyces cerevisiae.

Nafiseh Sirati, Ziying Shen, Nick K Olrichs, Blagovesta Popova, Iris C Verhoek, Ilse M Lagerwaard, Gerhard H Braus, Dora V Kaloyanova, J Bernd Helms

Journal of molecular biology 2023 Feb 28

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Golgi-Associated plant Pathogenesis Related protein 1 (GAPR-1) acts as a negative regulator of autophagy by interacting with Beclin 1 at Golgi membranes in mammalian cells. The molecular mechanism of this interaction is largely unknown. We recently showed that human GAPR-1 (hGAPR-1) has amyloidogenic properties resulting in the formation of protein condensates upon overexpression in Saccharomyces cerevisiae. Here we show that human Beclin 1 (hBeclin 1) has several predicted amyloidogenic regions and that overexpression of hBeclin 1-mCherry in yeast also results in the formation of fluorescent protein condensates. Surprisingly, co-expression of hGAPR-1-GFP and hBeclin 1-mCherry results in a strong reduction of hBeclin 1 condensates. Mutations of the known interaction site on the hGAPR-1 and hBeclin 1 surface abolished the effect on condensate formation during co-expression without affecting the condensate formation properties of the individual proteins. Similarly, a hBeclin 1-derived B18 peptide that is known to bind hGAPR-1 and to interfere with the interaction between hGAPR-1 and hBeclin 1, abolished the reduction of hBeclin 1 condensates by co-expression of hGAPR-1. These results indicate that the same type of protein-protein interactions interfere with condensate formation during co-expression of hGAPR-1 and hBeclin 1 as previously described for their interaction at Golgi membranes. The amyloidogenic properties of the B18 peptide were, however, important for the interaction with hGAPR-1, as mutant peptides with reduced amyloidogenic properties also showed reduced interaction with hGAPR-1 and reduced interference with hGAPR-1/hBeclin 1 condensate formation. We propose that amyloidogenic interactions take place between hGAPR-1 and hBeclin 1 prior to condensate formation. Copyright © 2023 The Authors. Published by Elsevier Ltd.. All rights reserved.

Citation

Nafiseh Sirati, Ziying Shen, Nick K Olrichs, Blagovesta Popova, Iris C Verhoek, Ilse M Lagerwaard, Gerhard H Braus, Dora V Kaloyanova, J Bernd Helms. GAPR-1 Interferes with Condensate Formation of Beclin 1 in Saccharomyces cerevisiae. Journal of molecular biology. 2023 Feb 28;435(4):167935