The membrane-topogenic vectorial behaviour of Nrf1 controls its post-translational modification and transactivation activity

• Published in: Scientific reports Vol. 3; no. 1; p. 2006
• Main Authors: Zhang, Yiguo, Hayes, John D.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 18.06.2013; Nature Publishing Group
• Subjects: 631/208/200; 631/337/458/1524; 631/337/572/2102; 631/45/221; Animals; Deglycosylation; Endoplasmic reticulum; Gene expression; Homeostasis; Humanities and Social Sciences; Isoforms; Membranes; Mice; multidisciplinary; Nuclear Respiratory Factor 1 - genetics; Nuclear Respiratory Factor 1 - physiology; Post-translation; Protein Biosynthesis; Proteinase; Proteolysis; Science; Transcriptional Activation; Translation
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep02006

The integral membrane-bound Nrf1 transcription factor fulfils important functions in maintaining cellular homeostasis and organ integrity, but how it is controlled vectorially is unknown. Herein, creative use of Gal4-based reporter assays with protease protection assays (GRAPPA) and double fluorescence protease protection (dFPP), reveals that the membrane-topogenic vectorial behaviour of Nrf1 dictates its post-translational modification and transactivation activity. Nrf1 is integrated within endoplasmic reticulum (ER) membranes through its NHB1-associated TM1 in cooperation with other semihydrophobic amphipathic regions. The transactivation domains (TADs) of Nrf1, including its Asn/Ser/Thr-rich (NST) glycodomain, are transiently translocated into the ER lumen, where it is glycosylated in the presence of glucose to become a 120-kDa isoform. Thereafter, the NST-adjoining TADs are partially repartitioned out of membranes into the cyto/nucleoplasmic side, where Nrf1 is subject to deglycosylation and/or proteolysis to generate 95-kDa and 85-kDa isoforms. Therefore, the vectorial process of Nrf1 controls its target gene expression.