title: Conformational role for the C-terminal tail of the intrinsically disordered high mobility group A (HMGA) chromatin factors.
abstract: The architectural factors HMGA are highly connected hubs in the chromatin network and affect key cellular functions. HMGA have a causal involvement in cancer development; in fact, truncated or chimeric HMGA forms, resulting from chromosomal rearrangements, lack the constitutively phosphorylated acidic C-terminal tail and display increased oncogenic potential, suggesting a functional role for this domain. HMGA belong to the intrinsically disordered protein category, and this prevents the use of classical approaches to obtain structural data. Therefore, we combined limited proteolysis, ion mobility separation-mass spectrometry (IMS-MS), and electrospray ionization-mass spectrometry (ESI-MS) to obtain structural information regarding full length and C-terminal truncated HMGA forms. Limited proteolysis indicates that HMGA acidic tail shields the inner portions of the protein. IMS-MS and ESI-MS show that HMGA proteins can assume a compact form and that the degree of compactness is dependent upon the presence of the acidic tail and its constitutive phosphorylations. Moreover, we demonstrate that C-terminal truncated forms and wild type proteins are post-translationally modified in a different manner. Therefore, we propose that the acidic tail and its phosphorylation could affect HMGA post-translational modification status and likely their activity. Finally, the mass spectrometry-based approach adopted here proves to be a valuable new tool to obtain structural data regarding intrinsically disordered proteins.
authors.affiliation: Department of Life Sciences, University of Trieste, Trieste, Italy.
authors.forename: Elisa
authors.initials: E
authors.lastname: Maurizio
authors.forename: Laetitia
authors.initials: L
authors.lastname: Cravello
authors.forename: Liam
authors.initials: L
authors.lastname: Brady
authors.forename: Barbara
authors.initials: B
authors.lastname: Spolaore
authors.forename: Laura
authors.initials: L
authors.lastname: Arnoldo
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Giancotti
authors.forename: Guidalberto
authors.initials: G
authors.lastname: Manfioletti
authors.forename: Riccardo
authors.initials: R
authors.lastname: Sgarra
mesh_terms: D000595:Amino Acid Sequence; D002471:Cell Transformation, Neoplastic / Q000235:genetics / Q000378:metabolism; D002843:Chromatin / Q000737:chemistry* / Q000378:metabolism; D024003:HMGA Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008745:Methylation; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D040901:Proteomics / Q000379:methods*; D011994:Recombinant Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D055672:Static Electricity
chemical_list: D002843:Chromatin; D024003:HMGA Proteins; D011994:Recombinant Proteins