The native-like interactions between SNase121 and SNase(111-143) fragments induce the recovery of their native-like structures and the ability to degrade DNA.
The interactions necessary for stabilizing the folding of the N-terminal large beta-subdomain and the C-terminal small alpha-subdomain of staphylococcal nuclease (SNase) were investigated by an approach of fragment complementation. Two SNase fragments, namely, SNase121 and SNase(111-143) containing 1-121 and 111-143 residues, respectively, of native SNase, were used in this study since the sequences of the two fragments correspond to that of the beta- and alpha-subdomains of SNase. SNase121 is a largely unfolded fragment whereas SNase(111-143) is a structureless fragment. The recognition process and efficiency of complementation of SNase121 and SNase(111-143) fragments were studied by NMR and various biochemical and biophysical methods. SNase121 and SNase(111-143) can recognize each other and recover their native conformations on binding, restoring the active site and the ability to degrade DNA. The SNase121:SNase(111-143) complex showed a nuclease activity up to 30% that of native SNase. The final rigid structures of SNase121 and SNase(111-143) fragments having the folded native-like beta-subdomain and alpha-subdomain structures of SNase, respectively, in the complex form simultaneously with the complex stabilization. Studies with the mutant SNase121 and SNase(111-143) fragments reveal that the sequence elements which are essential for recognition and efficient complementation of the two fragments are also necessary for recovering the native-like interactions at the binding interface between them. The interfragment interactions that induce the structural complementation of SNase121 and SNase(111-143) likely reflect the tertiary interactions necessary to stabilize the folding of both beta- and alpha-subdomains in the native SNase.
Geng
Yong
Y
National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Beijing 100101, China.
Feng
Yingang
Y
Xie
Tao
T
Shan
Lu
L
Wang
Jinfeng
J
D020134:Catalytic Domain / Q000235:genetics; D018360:Crystallography, X-Ray; D004269:DNA, Bacterial / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D008836:Micrococcal Nuclease / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010446:Peptide Fragments / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding / Q000235:genetics; D025941:Protein Interaction Mapping / Q000379:methods; D017434:Protein Structure, Tertiary / Q000235:genetics
D004269:DNA, Bacterial; D010446:Peptide Fragments; D008836:Micrococcal Nuclease