Minute Time Scale Prolyl Isomerization Governs Antibody Recognition of an Intrinsically Disordered Immunodominant Epitope

Fassolari, Marisol; Chemes, Lucía B.; Gallo, Mariana; Smal, Clara; Sánchez, Ignacio E.; Prat‐Gay, Gonzalo de

doi:10.1074/jbc.m112.444554

Cited by 15 publications

(18 citation statements)

References 62 publications

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“…In addition, in the NOESY spectrum, the diagnostic strong H δ -H α (i, i-1) NOEs for the trans -proline isomer was observed for P6 and P17 residues, while no H α -H α (i, i-1) cross peak, characteristic for the cis -proline conformation, was detected for either proline residue (data not shown). This is in contrast with the linker region joining the disordered N-terminal and the globular C-terminal domains of E7, which also harbors two proline residues (P41 and P47), that present a cis-trans isomeric equilibrium [29].…”

Section: Resultsmentioning

confidence: 91%

“…Given the tendency of E7C to oligomerize in the absence of E7N [40], TFE experiments could not be performed on this isolated domain. However, we will assume that the 27–50 fragment cannot stabilize α-helix because i) the highly acidic E7 (25–40) fragment is not sensitive to TFE addition, and ii) the inter-domain “hinge” region is rich in proline residues [29]. Therefore, we consider that the increase in α-helical content in E7 (27–98) upon TFE addition is due to the stabilization of native α-helix structure in the globular E7C domain [28] (Figure 4B).…”

Section: Resultsmentioning

confidence: 99%

“…Alternatively, the helix conformation may mediate binding to additional targets by this region. Interestingly, kinetic studies of complex formation between the retinoblastoma tumor suppressor AB domain and E7N fragments including E7 (21–29) revealed that if present, the sampling of conformational ensembles in this region is very fast [69] in contrast to the E7N-E7C hinge region, where the interaction mechanism with a specific antibody (M1) displays a slow conformational selection step involving proline isomerization [29]. The different timescales of conformational equilibria within E7N may be associated to a diversity of binding mechanisms, a salient feature of intrinsically disordered domains that may further contribute to their multi-target binding properties.…”

Section: Discussionmentioning

confidence: 99%

“…The human papillomavirus type-16 (HPV16) E7 oncoprotein, is a small, 98-amino acid acidic Zn 2+ binding protein composed of two domains, the N-terminal domain (E7N, residues 1–40) and the C-terminal domain (E7C, residues 51–98) [26]–[28], which are linked by a proline-rich hinge region [29]. The E7 protein is an extended dimer in solution, which can be described as an IDP [26], [30].…”

Section: Introductionmentioning

confidence: 99%

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Conformational Dissection of a Viral Intrinsically Disordered Domain Involved in Cellular Transformation

et al. 2013

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Intrinsic disorder is abundant in viral genomes and provides conformational plasticity to its protein products. In order to gain insight into its structure-function relationships, we carried out a comprehensive analysis of structural propensities within the intrinsically disordered N-terminal domain from the human papillomavirus type-16 E7 oncoprotein (E7N). Two E7N segments located within the conserved CR1 and CR2 regions present transient α-helix structure. The helix in the CR1 region spans residues L8 to L13 and overlaps with the E2F mimic linear motif. The second helix, located within the highly acidic CR2 region, presents a pH-dependent structural transition. At neutral pH the helix spans residues P17 to N29, which include the retinoblastoma tumor suppressor LxCxE binding motif (residues 21–29), while the acidic CKII-PEST region spanning residues E33 to I38 populates polyproline type II (PII) structure. At pH 5.0, the CR2 helix propagates up to residue I38 at the expense of loss of PII due to charge neutralization of acidic residues. Using truncated forms of HPV-16 E7, we confirmed that pH-induced changes in α-helix content are governed by the intrinsically disordered E7N domain. Interestingly, while at both pH the region encompassing the LxCxE motif adopts α-helical structure, the isolated 21–29 fragment including this stretch is unable to populate an α-helix even at high TFE concentrations. Thus, the E7N domain can populate dynamic but discrete structural ensembles by sampling α-helix-coil-PII-ß-sheet structures. This high plasticity may modulate the exposure of linear binding motifs responsible for its multi-target binding properties, leading to interference with key cell signaling pathways and eventually to cellular transformation by the virus.

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Section: Resultsmentioning

confidence: 91%