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SUMOylation of the hepatoma‐derived growth factor negatively influences its binding to chromatin
Author(s) -
Thakar Ketan,
Niedenthal Rainer,
Okaz Elwy,
Franken Sebastian,
Jakobs Astrid,
Gupta Shivangi,
Kelm Sørge,
Dietz Frank
Publication year - 2008
Publication title -
the febs journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.981
H-Index - 204
eISSN - 1742-4658
pISSN - 1742-464X
DOI - 10.1111/j.1742-4658.2008.06303.x
Subject(s) - sumo protein , lysine , microbiology and biotechnology , chromatin , chemistry , ubiquitin , internalization , biology , dna binding protein , growth factor , biochemistry , transcription factor , dna , cell , amino acid , receptor , gene
Hepatoma‐derived growth factor is a nuclear targeted mitogen containing a PWWP domain that mediates binding to DNA. To date, almost nothing is known about the molecular mechanisms of the functions of hepatoma‐derived growth factor, its routes of secretion and internalization or post‐translational modifications. In the present study, we show for the first time that hepatoma‐derived growth factor is modified by the covalent attachment of small ubiquitin‐related modifier 1 (SUMO‐1), a post‐translational modification with regulatory functions for an increasing number of proteins. Using a basal SUMOylation system in Escherichia coli followed by a MALDI‐TOF‐MS based peptide analysis, we identified the lysine residue SUMOylated located in the N‐terminal part of the protein adjacent to the PWWP domain. Surprisingly, this lysine residue is not part of the consensus motif described for SUMOylation. With a series of hepatoma‐derived growth factor mutants, we then confirmed that this unusual location is also used in mammalian cells and that SUMOylation of hepatoma‐derived growth factor takes place in the nucleus. Finally, we demonstrate that SUMOylated hepatoma‐derived growth factor is not binding to chromatin, in contrast to its unSUMOylated form. These observations potentially provide new perspectives for a better understanding of the functions of hepatoma‐derived growth factor.