title: The S. pombe translation initiation factor eIF4G is Sumoylated and associates with the SUMO protease Ulp2.
abstract: SUMO is a small post-translational modifier, that is attached to lysine residues in target proteins. It acts by altering protein-protein interactions, protein localisation and protein activity. SUMO chains can also act as substrates for ubiquitination, resulting in proteasome-mediated degradation of the target protein. SUMO is removed from target proteins by one of a number of specific proteases. The processes of sumoylation and desumoylation have well documented roles in DNA metabolism and in the maintenance of chromatin structure. To further analyse the role of this modification, we have purified protein complexes containing the S. pombe SUMO protease, Ulp2. These complexes contain proteins required for ribosome biogenesis, RNA stability and protein synthesis. Here we have focussed on two translation initiation factors that we identified as co-purifying with Ulp2, eIF4G and eIF3h. We demonstrate that eIF4G, but not eIF3h, is sumoylated. This modification is increased under conditions that produce cytoplasmic stress granules. Consistent with this we observe partial co-localisation of eIF4G and SUMO in stressed cells. Using HeLa cells, we demonstrate that human eIF4GI is also sumoylated; in vitro studies indicate that human eIF4GI is modified on K1368 and K1588, that are located in the C-terminal eIF4A- and Mnk-binding sites respectively.
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Jirapas
authors.initials: J
authors.lastname: Jongjitwimol
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Min
authors.initials: M
authors.lastname: Feng
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Lihong
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Oliver
authors.initials: O
authors.lastname: Wilkinson
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Lauren
authors.initials: L
authors.lastname: Small
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Robert
authors.initials: R
authors.lastname: Baldock
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Deborah L
authors.initials: DL
authors.lastname: Taylor
authors.affiliation: Paterson Institute for Cancer Research, The University of Manchester, Manchester, United Kingdom.
authors.forename: Duncan
authors.initials: D
authors.lastname: Smith
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Lucas D
authors.initials: LD
authors.lastname: Bowler
authors.affiliation: Biochemistry and Biomedical Sciences, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Simon J
authors.initials: SJ
authors.lastname: Morley
authors.affiliation: Genome Damage and Stability Centre, School of Life Sciences, University of Sussex, Falmer, Brighton, United Kingdom.
authors.forename: Felicity Z
authors.initials: FZ
authors.lastname: Watts
mesh_terms: D010450:Endopeptidases / Q000378:metabolism*; D039603:Eukaryotic Initiation Factor-4G / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D012568:Schizosaccharomyces / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000378:metabolism*; D058207:Sumoylation / Q000502:physiology*
chemical_list: D039603:Eukaryotic Initiation Factor-4G; D029702:Schizosaccharomyces pombe Proteins; D010450:Endopeptidases