DNA ligases are essential guardians of genome integrity by virtue of their ability to recognize and seal 3'-OH/5'-phosphate nicks in duplex DNA. The substrate binding and three chemical steps of the ligation pathway are coupled to global and local changes in ligase structure, involving both massive protein domain movements and subtle remodeling of atomic contacts in the active site. Here we applied solution NMR spectroscopy to study the conformational dynamics of the Chlorella virus DNA ligase (ChVLig), a minimized eukaryal ATP-dependent ligase consisting of nucleotidyltransferase, OB, and latch domains. Our analysis of backbone (15)N spin relaxation and (15)N,(1)H residual dipolar couplings of the covalent ChVLig-AMP intermediate revealed conformational sampling on fast (picosecond to nanosecond) and slow timescales (microsecond to millisecond), indicative of interdomain and intradomain flexibility. We identified local and global changes in ChVLig-AMP structure and dynamics induced by phosphate. In particular, the chemical shift perturbations elicited by phosphate were clustered in the peptide motifs that comprise the active site. We hypothesize that phosphate anion mimics some of the conformational transitions that occur when ligase-adenylate interacts with the nick 5'-phosphate.
Pubmed ID: 19913033 RIS Download
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A graphical NMR assignment and integration program for proteins, nucleic acids, and other polymers. Sparky displays NMR spectra, the peaks of which users may pick, assign, and integrate using a graphical interface. Users can work with any number of 2, 3 or 4 dimensional spectra simultaneously. Spectra for input to Sparky can be produced with processing programs NMRPipe, Felix, VNMR, XWinNMR or UXNMR. Output consists of text peak lists showing assignments, chemical shifts, volumes, line widths, etc.
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