Dataset Information

Folding and misfolding of the papillomavirus E6 interacting peptide E6ap.

ABSTRACT: All-atom Langevin dynamics simulations have been performed to study the folding pathways of the 18-residue binding domain fragment E6ap of the human papillomavirus E6 interacting peptide. Six independent folding trajectories, with a total duration of nearly 2 micros, all lead to the same native state in which the E6ap adopts a fluctuating alpha-helix structure in the central portion (Ser-4-Leu-13) but with very flexible N and C termini. Simulations starting from different core configurations exhibit the E6ap folding dynamics as either a two- or three-state folder with an intermediate misfolded state. The essential leucine hydrophobic core (Leu-9, Leu-12, and Leu-13) is well conserved in the native-state structure but absent in the intermediate structure, suggesting that the leucine core is not only essential for the binding activity of E6ap but also important for the stability of the native structure. The free energy landscape reveals a significant barrier between the basins separating the native and misfolded states. We also discuss the various underlying forces that drive the peptide into its native state.

SUBMITTER: Cui B

PROVIDER: S-EPMC165834 | biostudies-literature | 2003 Jun

REPOSITORIES: biostudies-literature

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Publications

Folding and misfolding of the papillomavirus E6 interacting peptide E6ap.

Cui Bianxiao B Shen Min-Yi MY Freed Karl F KF

Proceedings of the National Academy of Sciences of the United States of America 20030527 12

All-atom Langevin dynamics simulations have been performed to study the folding pathways of the 18-residue binding domain fragment E6ap of the human papillomavirus E6 interacting peptide. Six independent folding trajectories, with a total duration of nearly 2 micros, all lead to the same native state in which the E6ap adopts a fluctuating alpha-helix structure in the central portion (Ser-4-Leu-13) but with very flexible N and C termini. Simulations starting from different core configurations exh ...[more]

PMID: 12771374

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Project description:The degradation of p53 is a hallmark of high-risk human papillomaviruses (HPVs) of the alpha genus and HPV-related carcinogenicity. The oncoprotein E6 forms a ternary complex with the E3 ubiquitin ligase E6-associated protein (E6AP) and tumor suppressor protein p53 targeting p53 for ubiquitination. The extent of p53 degradation by different E6 proteins varies greatly, even for the closely related HPV16 and HPV31. HPV16 E6 and HPV31 E6 display high sequence identity (∼67%). We report here, for the first time, the structure of HPV31 E6 bound to the LxxLL motif of E6AP. HPV16 E6 and HPV31 E6 are structurally very similar, in agreement with the high sequence conservation. Both E6 proteins bind E6AP and degrade p53. However, the binding affinities of 31 E6 to the LxxLL motif of E6AP and p53, respectively, are reduced 2-fold and 5.4-fold compared to 16 E6. The affinity of E6-E6AP-p53 ternary complex formation parallels the efficacy of the subsequent reaction, namely, degradation of p53. Therefore, closely related E6 proteins addressing the same cellular targets may still diverge in their binding efficiencies, possibly explaining their different phenotypic or pathological impacts.IMPORTANCE Variations of carcinogenicity of human papillomaviruses are related to variations of the E6 and E7 interactome. While different HPV species and genera are known to target distinct host proteins, the fine differences between E6 and E7 of closely related HPVs, supposed to target the same cellular protein pools, remain to be addressed. We compare the oncogenic E6 proteins of the closely related high-risk HPV31 and HPV16 with regard to their structure and their efficiency of ternary complex formation with their cellular targets p53 and E6AP, which results in p53 degradation. We solved the crystal structure of 31 E6 bound to the E6AP LxxLL motif. HPV16 E6 and 31 E6 structures are highly similar, but a few sequence variations lead to different protein contacts within the ternary complex and, as quantified here, an overall lower binding affinity of 31 E6 than 16 E6. These results align with the observed lower p53 degradation potential of 31 E6.

Dataset Information

Folding and misfolding of the papillomavirus E6 interacting peptide E6ap.

Publications

Folding and misfolding of the papillomavirus E6 interacting peptide E6ap.

Similar Datasets

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