Metal-controlled Interdomain Cooperativity in Parvalbumins
Document Type
Article
Publication Date
2009
Keywords
Thermodynamics, Cooperativity, Thermodynamic Domain, Structural Domain, Ef-hand, Protein Unfolding, Protein Denaturation, Intermediate, Metal Binding, Protein Cavities, Protein Intrinsic Disorder, Hyperthermophile, Allergen
Digital Object Identifier (DOI)
https://doi.org/10.1016/j.ceca.2009.07.001
Abstract
Conformational behavior of five homologous proteins, parvalbumins (PAs) from northern pike (α and β isoforms), Baltic cod, and rat (α and β isoforms), was studied by scanning calorimetry, circular dichroism, and bis-ANS fluorescence. The mechanism of the temperature-induced denaturation of these proteins depends dramatically on both the peculiarities of their amino acid sequences and on their interaction with metal ions. For example, the pike α-PA melting can be described by two successive two-state transitions with mid-temperatures of 90 and 120 °C, suggesting the presence of two thermodynamic domains. The intermediate state populated at the end of the first transition was shown to bind Ca2+ ions, and was characterized by the largely preserved secondary structure and increased solvent exposure of hydrophobic groups. Mg2+- and Na+-loaded forms of pike α-PA demonstrated a single two-state transition. Therefore, the mechanism of the PA thermal denaturation is controlled by metal binding. It ranged from the absence of detectable first-order transition (apo-form of pike PA), to the two-state transition (e.g., Mg2+- and Na+-loaded forms of pike α-PA), to the more complex mechanisms (Ca2+-loaded PAs) involving at least one partially folded intermediate. Analysis of isolated cavities in the protein structures revealed that the interface between the CD and EF subdomains of Ca2+-loaded pike α-PA is much more loosely packed compared with PAs manifesting single heat-sorption peak. The impairment of interactions between CD and EF subdomains may cause a loss of structural cooperativity and appearance of two separate thermodynamic domains. One more peculiar feature of pike α-PA is that depending on its interactions with metal ions, it can be an intrinsically disordered protein (apo-form), an ordered protein of mesophilic (Na+-bound state), thermophilic (Mg2+-form), or even of the hyperthermophilic origin (Ca2+-form).
Was this content written or created while at USF?
Yes
Citation / Publisher Attribution
Cell Calcium, v. 46, issue 3, p. 163-175
Scholar Commons Citation
Permyakov, Sergei E.; Bakunts, Anush G.; Permyakova, Maria E.; Denesyuk, Alexander I.; Uversky, Vladimir N.; and Permyakov, Eugene A., "Metal-controlled Interdomain Cooperativity in Parvalbumins" (2009). Molecular Medicine Faculty Publications. 563.
https://digitalcommons.usf.edu/mme_facpub/563
