title: Nuclear Localization Signal and p53 Binding Site in MAP/ERK Kinase Kinase 1 (MEKK1).
abstract: Previously, we showed that Mekk1 translocates to the nucleus, interacts with tumor suppressor protein p53, and co-represses PKD1 transcription via an atypical p53 binding site on the minimal PKD1 promoter (JBC 285:38,818-38,831, 2010). In this study, we report the mechanisms of Mekk1 nuclear transport and p53 binding. Using GFP-linked constitutively active-Mekk1 (CA-Mekk1) and a deletion strategy, we identified a nuclear localization signal (HRDVK) located at amino acid (aa) residues 1,349-1,353 in the C-terminal Mekk1 catalytic domain. Deletion of this sequence in CA-Mekk1 and full-length Mekk1 significantly reduced their nuclear translocation in both HEK293T and COS-1 cells. Using co-immunoprecipitation, we identified an adjacent sequence (GANLID, aa 1,354-1,360) in Mekk1 responsible for p53 binding. Deletion of this sequence markedly reduced the interaction of Mekk1 with p53. Mekk1 does not appear to affect phosphorylation of Ser15, located in the Mdm2 interaction site, or other Ser residues in p53. However, Mekk1 mediates p53 protein stability in the presence of Mdm2 and reduces p53 ubiquitination, suggesting an interference with Mdm2-mediated degradation of p53 by the ubiquitin-proteasome pathway.
authors.affiliation: Laboratory of Biochemistry, Garrett-Strong Science Building 3100, 800 University Drive, Northwest Missouri State University, Maryville, Missouri, 64468.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Chipps
authors.affiliation: Laboratory of Biochemistry, Garrett-Strong Science Building 3100, 800 University Drive, Northwest Missouri State University, Maryville, Missouri, 64468.
authors.forename: April
authors.initials: A
authors.lastname: Protzman
authors.affiliation: Laboratory of Biochemistry, Garrett-Strong Science Building 3100, 800 University Drive, Northwest Missouri State University, Maryville, Missouri, 64468.
authors.forename: M Zubayed
authors.initials: MZ
authors.lastname: Muhi
authors.affiliation: Laboratory of Biochemistry, Garrett-Strong Science Building 3100, 800 University Drive, Northwest Missouri State University, Maryville, Missouri, 64468.
authors.forename: Shoko
authors.initials: S
authors.lastname: Ando
authors.affiliation: Department of Biochemistry and Molecular Biology and the Kidney Institute, University of Kansas Medical Center, Kansas City, Kansas, 66160.
authors.forename: James P
authors.initials: JP
authors.lastname: Calvet
authors.affiliation: Laboratory of Biochemistry, Garrett-Strong Science Building 3100, 800 University Drive, Northwest Missouri State University, Maryville, Missouri, 64468.
authors.forename: M Rafiq
authors.initials: MR
authors.lastname: Islam
mesh_terms: D000818:Animals; D001665:Binding Sites; D019556:COS Cells; D002522:Chlorocebus aethiops; D057809:HEK293 Cells; D006801:Humans; D048728:MAP Kinase Kinase Kinase 1 / Q000235:genetics / Q000378:metabolism*; D019913:Nuclear Localization Signals / Q000235:genetics / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism; D011485:Protein Binding; D055550:Protein Stability; D051736:Proto-Oncogene Proteins c-mdm2 / Q000235:genetics / Q000378:metabolism*; D050396:TRPP Cation Channels / Q000235:genetics / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics / Q000378:metabolism*; D054875:Ubiquitination / Q000235:genetics
chemical_list: D048728:MAP Kinase Kinase Kinase 1; D019913:Nuclear Localization Signals; D046988:Proteasome Endopeptidase Complex; D051736:Proto-Oncogene Proteins c-mdm2; D050396:TRPP Cation Channels; D016159:Tumor Suppressor Protein p53; C495901:TP53 protein, human; C497206:MDM2 protein, human
keywords: MEKK1; NUCLEAR LOCALIZATION SIGNAL; p53; p53 BINDING SITE