NMR studies on the surface accessibility of the archaeal protein Sso7d by using TEMPOL and Gd(III)(DTPA-BMA) as paramagnetic probes.
Understanding how proteins are approached by surrounding molecules is fundamental to increase our knowledge of life at atomic resolution. Here, the surface accessibility of a multifunctional small protein, the archaeal protein Sso7d from Sulfolobus solfataricus, has been investigated by using TEMPOL and Gd(III)(DTPA-BMA) as paramagnetic probes. The DNA binding domain of Sso7d appears very accessible both to TEMPOL and Gd(III)(DTPA-BMA). Differences in paramagnetic attenuation profiles of (1)H-(15)N HSQC protein backbone amide correlations, observed in the presence of the latter paramagnetic probes, are consistent with the hydrogen bond acceptor capability of the N-oxyl moiety of TEMPOL to surface exposed Sso7d amide groups. By using the gadolinium complex as a paramagnetic probe a better agreement between Sso7d structural features and attenuation profile is achieved. It is interesting to note that the protein P-loop region, in spite of the high surface exposure predicted by the available protein structures, is not approached by TEMPOL and only partially by Gd(III)(DTPA-BMA).
Bernini
Andrea
A
Università degli Studi di Siena, Dipartimento di Biologia Molecolare, via A. Fiorentina 1, 53100 Siena, Italy.
Venditti
Vincenzo
V
Spiga
Ottavia
O
Ciutti
Arianna
A
Prischi
Filippo
F
Consonni
Roberto
R
Zetta
Lucia
L
Arosio
Ivana
I
Fusi
Paola
P
Guagliardi
Annamaria
A
Niccolai
Neri
N
D000577:Amides / Q000737:chemistry; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry*; D003497:Cyclic N-Oxides / Q000737:chemistry*; D004268:DNA-Binding Proteins / Q000737:chemistry*; D019786:Gadolinium DTPA / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D011522:Protons; D013113:Spin Labels; D013499:Surface Properties
D000577:Amides; D019843:Archaeal Proteins; D003497:Cyclic N-Oxides; D004268:DNA-Binding Proteins; D009587:Nitrogen Isotopes; D011522:Protons; D013113:Spin Labels; C093228:Sso7d protein, Sulfolobus; C064925:gadodiamide; D019786:Gadolinium DTPA; C001803:tempol