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Cell Rep. 2018 Jan 2;22(1):17-26. doi: 10.1016/j.celrep.2017.12.031.

Oxygen-Sensitive Remodeling of Central Carbon Metabolism by Archaic eIF5B.

Author information

1
Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL 33136, USA.
2
The SickKids Proteomics, Analytics, Robotics & Chemical Biology Centre (SPARC BioCentre), The Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.
3
Department of Biochemistry and Molecular Biology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; Sylvester Comprehensive Cancer Center, Miller School of Medicine, University of Miami, Miami, FL 33136, USA; Department of Urology, Miller School of Medicine, University of Miami, Miami, FL 33136, USA. Electronic address: stephenlee@med.miami.edu.

Abstract

The eukaryotic translation initiation factor 5B (eIF5B) is a homolog of IF2, an ancient translation factor that enables initiator methionine-tRNAiMet (met-tRNAiMet) loading on prokaryotic ribosomes. While it can be traced back to the last universal common ancestor, eIF5B is curiously dispensable in modern aerobic yeast and mammalian cells. Here, we show that eIF5B is an essential element of the cellular hypoxic cap-dependent protein synthesis machinery. System-wide interrogation of dynamic translation machineries by MATRIX (mass spectrometry analysis of active translation factors using ribosome density fractionation and isotopic labeling experiments) demonstrated augmented eIF5B activity in hypoxic translating ribosomes. Global translatome studies revealed central carbon metabolism, cellular hypoxic adaptation, and ATF4-mediated stress response as major eIF5B-dependent pathways. These primordial processes rely on eIF5B even in the presence of oxygen and active eIF2, the canonical recruiter of met-tRNAiMet in eukaryotes. We suggest that aerobic eukarya retained eIF5B/IF2 to remodel anaerobic pathways during episodes of oxygen deficiency.

KEYWORDS:

ATF4; IF2; MATRIX; carbon metabolism; eIF5B; evolution; glycolysis; hypoxia; stress; translation

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