Human papillomavirus 18 E1^E4 protein interacts with cyclin A/CDK 2 through an RXL motif.
The human papilloma virus E4 protein is highly expressed in late times of infection. Evidence to date suggests that E4 is essential for amplification of the viral genome and that it can influence cell cycle. Examination of the sequences encoding the E4 proteins from several genotypes of human papillomavirus revealed the presence of RXL-containing motifs reminiscent of the cyclin-binding motifs that have been identified in several cyclin-binding proteins. When baculovirus-produced human cyclin E and cyclin A with cdk2 were incubated in vitro with a GST-E4 fusion protein, both cyclin E and A stably interacted with the GST-E4 protein containing the full E4 sequence from HPV18. The interaction was not dependent on the presence of the kinase subunit but was dependent on the integrity of the RXL motif in E4. When incubated with cell extracts from the C33A human cervical carcinoma cell line or when expressed in C33A cells, the GST-E4 protein formed interactions with cyclin A and cdk2 and kinase activity could be demonstrated in the GST-E4 complex. In contrast to the baculovirus-produced cyclin E, cellular cyclin E failed to detectably interact with GST-E4 suggesting that the HPV18 E4 sequences are capable of interacting only with cyclin A in mammalian cells. These observations suggest that human papillomavirus E4 proteins can interact with cyclin A/cdk2, which may contribute to viral manipulation of the host cell cycle.
Department of Pathology and Molecular Medicine, McMaster University, 1280 Main Street West, Hamilton, ON L8S 4K1, Canada. qding@robarts.ca
Qingming
Q
Ding
Lili
L
Li
Peter
P
Whyte
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D045744:Cell Line, Tumor; D019925:Cyclin A / Q000737:chemistry*; D051357:Cyclin-Dependent Kinase 2 / Q000737:chemistry*; D052161:Human papillomavirus 18; D006801:Humans; D008969:Molecular Sequence Data; D009856:Oncogene Proteins, Viral / Q000737:chemistry*; D010446:Peptide Fragments / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D054730:Protein Interaction Domains and Motifs; D011494:Protein Kinases / Q000737:chemistry / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D061987:Sf9 Cells; D018411:Spodoptera
D019925:Cyclin A; D009856:Oncogene Proteins, Viral; D010446:Peptide Fragments; C084762:oncogene protein E1, Human papillomavirus type 18; C468296:oncogene protein E4, Human papillomavirus type 18; D011494:Protein Kinases; C102333:histone H1 kinase; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2