title: Insights into K-Ras 4B regulation by post-translational lysine acetylation.
abstract: Ras is a molecular switch cycling between an active, GTP-bound and an inactive, GDP-bound state. Mutations in Ras, mostly affecting the off-switch, are found in many human tumours. Recently, it has been shown that K-Ras 4B is targeted by lysine acetylation at K104. Based on results obtained for an acetylation mimetic Ras mutant (K104Q), it was hypothesised that K104-acetylation might interfere with its oncogenicity by impairing SOS-catalysed guanine-nucleotide exchange. We prepared site-specifically K104-acetylated K-Ras 4B and the corresponding oncogenic mutant protein G12V using the genetic-code expansion concept. We found that SOS-catalysed nucleotide exchange, also of allosterically activated SOS, was neither affected by acetylation of K104 in wildtype K-Ras 4B nor in the G12V mutant, suggesting that glutamine is a poor mimetic for acetylation at this site. In vitro, the lysine-acetyltransferases CBP and p300 were able to acetylate both, wildtype and G12V K-Ras 4B. In addition to K104 we identified further acetylation sites in K-Ras 4B, including K147, within the important G5/SAK-motif. However, the intrinsic and the SOS-catalysed nucleotide exchange was not affected by K147-acetylation of K-Ras 4B. Finally, we show that Sirt2 and HDAC6 do neither deacetylate K-Ras 4B if acetylated at K104 nor if acetylated at K147 in vitro.
authors.forename: Philipp
authors.initials: P
authors.lastname: Knyphausen
authors.forename: Franziska
authors.initials: F
authors.lastname: Lang
authors.forename: Linda
authors.initials: L
authors.lastname: Baldus
authors.forename: Antje
authors.initials: A
authors.lastname: Extra
authors.forename: Michael
authors.initials: M
authors.lastname: Lammers
mesh_terms: D000107:Acetylation; D000494:Allosteric Regulation; D000595:Amino Acid Sequence; D000818:Animals; D055162:Biocatalysis; D006801:Humans; D008239:Lysine / Q000378:metabolism*; D008958:Models, Molecular; D009154:Mutation; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D016283:Proto-Oncogene Proteins p21(ras) / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020664:Son of Sevenless Proteins / Q000378:metabolism
chemical_list: D020664:Son of Sevenless Proteins; D016283:Proto-Oncogene Proteins p21(ras); D008239:Lysine