Interaction between cyclin-dependent kinases and human papillomavirus replication-initiation protein E1 is required for efficient viral replication.
We have identified the human papillomavirus (HPV) DNA replication initiation protein E1 as a tight-binding substrate of cyclin E/cyclin-dependent kinase (Cdk) complexes by using expression cloning. E1, a DNA helicase, collaborates with the HPV E2 protein in ori-dependent replication. E1 formed complexes with cyclin E in insect and mammalian cells, independent of Cdks and E2. Additional cyclins, including A-, B-, and F-type (but not D-type), interacted with the E1/E2 complex, and A- and E-type cyclin kinases were capable of phosphorylating E1 and E2 in vitro. Association with cyclins and efficient phosphorylation of E1 required the presence of a cyclin interaction motif (the RXL motif). E1 lacking the RXL motif displayed defects in E2-dependent HPV ori replication in vivo. Consistent with a role for Cdk-mediated phosphorylation in E1 function, an E1 protein lacking all four candidate Cdk phosphorylation sites still associated with E2 and cyclin E but was impaired in HPV replication in vitro and in vivo. Our data reveal a link between cyclin/Cdk function and activation of HPV DNA replication through targeting of Cdk complexes to the E1 replication-initiation protein and suggest a functional role for E1 phosphorylation by Cdks. The use of cyclin-binding RXL motifs is now emerging as a major mechanism by which cyclins are targeted to key substrates.
Ma
T
T
Department of Biochemistry, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA.
Zou
N
N
Lin
B Y
BY
Chow
L T
LT
Harper
J W
JW
D003001:Cloning, Molecular; D018844:Cyclin-Dependent Kinases / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism; D004265:DNA Helicases / Q000235:genetics*; D004261:DNA Replication / Q000235:genetics; D006801:Humans; D027383:Papillomaviridae / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding / Q000235:genetics; D014764:Viral Proteins / Q000378:metabolism; D014779:Virus Replication
D016213:Cyclins; D014764:Viral Proteins; D018844:Cyclin-Dependent Kinases; D004265:DNA Helicases