HPV E6 and MAGUK protein interactions: determination of the molecular basis for specific protein recognition and degradation.
It has recently been shown that the high-risk human papillomavirus (HPV) E6 proteins can target the PDZ-domain containing proteins, Dlg, MUPP-1, MAGI-1 and hScrib for proteasome-mediated degradation. However, the E6 proteins from HPV-16 and HPV-18 (the two most common high-risk virus types) differ in their ability to target these proteins in a manner that correlates with their malignant potential. To investigate the underlying mechanisms for this, we have mutated HPV-16 and HPV-18 E6s to give each protein the other's PDZ-binding motif. Analysis of these mutants shows that the greater ability of HPV-18 E6 to bind to these proteins and to target them for degradation is indeed due to a single amino acid difference. Using a number of assays, we show that the E6 proteins interact specifically with only one of the five PDZ domains of MAGI-1, and this is the first interaction described for this particular PDZ domain. We also show that the guanylate kinase homology domain and the regions of MAGI-1 downstream of amino acid 733 are not required for the degradation of MAGI-1. Finally, in a series of comparative analyses, we show that the degradation of MAGI-1 occurs through a different mechanism from that used by the E6 protein to induce the degradation of Dlg and p53.
Thomas
M
M
International Centre for Genetic Engineering and Biotechnology, Padriciano 99, I-34012 Trieste, Italy.
Glaunsinger
B
B
Pim
D
D
Javier
R
R
Banks
L
L
D020816:Amino Acid Motifs; D000818:Animals; D004252:DNA Mutational Analysis; D004268:DNA-Binding Proteins; D051528:Guanylate Kinases; D009154:Mutation; D009703:Nucleoside-Phosphate Kinase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D009856:Oncogene Proteins, Viral / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000378:metabolism; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism
D004268:DNA-Binding Proteins; C068651:E6 protein, Human papillomavirus type 16; C052603:E6 protein, Human papillomavirus type 18; D009856:Oncogene Proteins, Viral; D011506:Proteins; D012097:Repressor Proteins; D016159:Tumor Suppressor Protein p53; D009703:Nucleoside-Phosphate Kinase; D051528:Guanylate Kinases