RT Journal Article
SR Electronic
T1 A di-acidic motif targets cytoplasmic proteins for unconventional protein secretion
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 122028
DO 10.1101/122028
A1 David Cruz-Garcia
A1 Nathalie Brouwers
A1 Juan M. Duran
A1 Amy J. Curwin
A1 Vivek Malhotra
YR 2017
UL http://biorxiv.org/content/early/2017/03/29/122028.abstract
AB We previously reported that Acb1, a cytoplasmic protein in Saccharomyces cerevisiae that cannot enter the endoplasmic reticulum (ER), was secreted upon nutrient starvation by a Vps4 independent, but ESCRT-I, -II and -III and Grh1 dependent pathway (Curwin et al., 2016). Here, we report that the same conditions result in secretion of another signal sequence lacking protein, superoxide dismutase 1 (SOD1). Similar to Acb1, SOD1 export requires Grh1 and a subset of ESCRT components. Importantly, our analysis reveals the existence of a conserved di-acidic motif (Asp-Glu) in SOD1 and Acb1 that is required for their respective export. This sequence is different from the di-acidic motif (Asp-X-Glu) necessary for export of transmembrane proteins from the ER. We propose that the Asp-Glu sequence acts as a targeting motif for the entry of SOD1 and Acb1, and likely many other proteins, upon nutrient starvation into a common albeit ER-Golgi independent pathway of secretion.