The intrinsically disordered RNR inhibitor Sml1 is a dynamic dimer
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The intrinsically disordered RNR inhibitor Sml1 is a dynamic dimer. / Danielsson, Jens; Liljedahl, Leena; Ba´ra´ny-Wallje, Elsa; Sønderby, Pernille; Kristensen, Line Hyltoft; Martinez-Yamout, Maria A; Dyson, H Jane; Wright, Peter E; Poulsen, Flemming M; Ma¨ler, Lena; Gra¨slund, Astrid; Kragelund, Birthe B.
In: Biochemistry, Vol. 47, No. 50, 2008, p. 13428-13437.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - The intrinsically disordered RNR inhibitor Sml1 is a dynamic dimer
AU - Danielsson, Jens
AU - Liljedahl, Leena
AU - Ba´ra´ny-Wallje, Elsa
AU - Sønderby, Pernille
AU - Kristensen, Line Hyltoft
AU - Martinez-Yamout, Maria A
AU - Dyson, H Jane
AU - Wright, Peter E
AU - Poulsen, Flemming M
AU - Ma¨ler, Lena
AU - Gra¨slund, Astrid
AU - Kragelund, Birthe B
N1 - Keywords: Amino Acid Sequence; Conserved Sequence; Dimerization; Molecular Sequence Data; Peptide Fragments; Protein Binding; Protein Structure, Tertiary; Ribonucleotide Reductases; Saccharomyces cerevisiae Proteins; Thermodynamics
PY - 2008
Y1 - 2008
N2 - Sml1 is a small ribonucleotide reductase (RNR) regulatory protein in Saccharomyces cerevisiae that binds to and inhibits RNR activation. NMR studies of (15)N-labeled Sml1 (104 residues), as well as of a truncated variant (residues 50-104), have allowed characterization of their molecular properties. Sml1 belongs to the class of intrinsically disordered proteins with a high degree of dynamics and very little stable structure. Earlier suggestions for a dimeric structure of Sml1 were confirmed, and from translation diffusion NMR measurements, a dimerization dissociation constant of 0.1 mM at 4 degrees C could be determined. The hydrodynamic radius for the monomeric form of Sml1 was determined to be 23.4 A, corresponding to a protein size between those of a globular protein and a coil. Formation of a dimer results in a hydrodynamic radius of 34.4 A. The observed chemical shifts showed in agreement with previous studies two segments with transient helical structure, residues 4-20 and 60-86, and relaxation studies clearly showed restricted motion in these segments. A spin-label attached to C14 showed long-range interactions with residues 60-70 and 85-95, suggesting that the N-terminal domain folds onto the C-terminal domain. Importantly, protease degradation studies combined with mass spectrometry indicated that the N-terminal domain is degraded before the C-terminal region and thus may serve as a protection against proteolysis of the functionally important C-terminal region. Dimer formation was not associated with significant induction of structure but was found to provide further protection against proteolysis. We propose that this molecular shielding and protection of vital functional structures from degradation by functionally unimportant sites may be a general attribute of other natively disordered proteins.
AB - Sml1 is a small ribonucleotide reductase (RNR) regulatory protein in Saccharomyces cerevisiae that binds to and inhibits RNR activation. NMR studies of (15)N-labeled Sml1 (104 residues), as well as of a truncated variant (residues 50-104), have allowed characterization of their molecular properties. Sml1 belongs to the class of intrinsically disordered proteins with a high degree of dynamics and very little stable structure. Earlier suggestions for a dimeric structure of Sml1 were confirmed, and from translation diffusion NMR measurements, a dimerization dissociation constant of 0.1 mM at 4 degrees C could be determined. The hydrodynamic radius for the monomeric form of Sml1 was determined to be 23.4 A, corresponding to a protein size between those of a globular protein and a coil. Formation of a dimer results in a hydrodynamic radius of 34.4 A. The observed chemical shifts showed in agreement with previous studies two segments with transient helical structure, residues 4-20 and 60-86, and relaxation studies clearly showed restricted motion in these segments. A spin-label attached to C14 showed long-range interactions with residues 60-70 and 85-95, suggesting that the N-terminal domain folds onto the C-terminal domain. Importantly, protease degradation studies combined with mass spectrometry indicated that the N-terminal domain is degraded before the C-terminal region and thus may serve as a protection against proteolysis of the functionally important C-terminal region. Dimer formation was not associated with significant induction of structure but was found to provide further protection against proteolysis. We propose that this molecular shielding and protection of vital functional structures from degradation by functionally unimportant sites may be a general attribute of other natively disordered proteins.
U2 - 10.1021/bi801040b
DO - 10.1021/bi801040b
M3 - Journal article
C2 - 19086274
VL - 47
SP - 13428
EP - 13437
JO - Biochemistry
JF - Biochemistry
SN - 0006-2960
IS - 50
ER -
ID: 18656815