@article {1103, title = {Dissecting the domain structure of Cdc4p, a myosin essential light chain involved in Schizosaccharomyces pombe cytokinesis}, journal = {Biochemistry}, volume = {44}, number = {36}, year = {2005}, note = {ISI Document Delivery No.: 962ZGTimes Cited: 3Cited Reference Count: 75}, month = {Sep}, pages = {12136-12148}, type = {Article}, abstract = {Cytokinesis is the process by which one cell divides into two. Key in the cytokinetic mechanism of Schizosaccharomyces pombe is the contractile ring myosin, which consists of two heavy chains (Myo2p), two essential light chains (Cdc4p), and two regulatory light chains (R1c1p). Cdc4p is a dumbbell-shaped EF-hand protein composed of N- and C-terminal domains separated by a flexible linker. The properties of these two domains are of particular interest because each is hypothesized to have independent functions in binding different components of the cytokinesis machinery. To help define these properties, we used NMR spectroscopy to compare the structure, stability, and dynamics of the isolated N- and C-terminal domains with one another and with native Cdc4p. On the basis of invariant chemical shifts, the N-domain retains the same structure in isolation as in the context of the full-length Cdc4p, whereas the C-domain appears markedly perturbed. This perturbation results from intramolecular binding of the residual linker sequence at the N-terminus of the C-domain in a mode similar to that used by native Cdc4p to associate with target polypeptide sequences. NMR relaxation, thermal denaturation, and amide hydrogen exchange experiments also indicate that the C-domain is less stable and more dynamic than the N-domain, both in isolation and in the full-length protein. We hypothesize that these properties reflect a conformational plasticity of the C-domain, which may allow Cdc4p to interact with several regulatory or contractile ring proteins necessary for cytokinesis.}, keywords = {CALCIUM-MODULATED PROTEINS, CONFORMATIONAL CHANGE, CONTRACTILE RING, FISSION, GROUP, HYDROGEN-EXCHANGE, MUSCLE TROPONIN-C, N-15 NMR RELAXATION, NUCLEAR MAGNETIC-RESONANCE, SACCHAROMYCES-CEREVISIAE, SKELETAL-MUSCLE, YEAST}, isbn = {0006-2960}, url = {://000231771500022}, author = {Escobar-Cabrera, E. and Venkatesan, M. and Desautels, M. and Hemmingsen, S. M. and McIntosh, L. P.} } @article {1223, title = {Letter to the editor: Backbone chemical shift assignments of the LexA catalytic domain in its active conformation}, journal = {Journal of Biomolecular Nmr}, volume = {31}, number = {4}, year = {2005}, note = {ISI Document Delivery No.: 931SKTimes Cited: 1Cited Reference Count: 7}, month = {Apr}, pages = {371-372}, type = {Article}, keywords = {auto-proteolysis, DYNAMICS, LexA, N-15 NMR RELAXATION, NMR ASSIGNMENTS, PROTEIN, SOS response}, isbn = {0925-2738}, url = {://000229505400016}, author = {Okon, M. and Pfuetzner, R. and Vuckovic, M. and Little, J. W. and Strynadka, N. C. J. and McIntosh, L. P.} } @article {1165, title = {The structural and dynamic basis of Ets-1 DNA binding autoinhibition}, journal = {Journal of Biological Chemistry}, volume = {280}, number = {8}, year = {2005}, note = {ISI Document Delivery No.: 902DTTimes Cited: 19Cited Reference Count: 73}, month = {Feb}, pages = {7088-7099}, type = {Article}, abstract = {The transcription factor Ets-1 is regulated by the allosteric coupling of DNA binding with the unfolding of an alpha-helix (HI-1) within an autoinhibitory module. To understand the structural and dynamic basis for this autoinhibition, we have used NAIR spectroscopy to characterize Ets-1DeltaN301, a partially inhibited fragment of Ets-1. The NMR-derived Ets-1DeltaN301 structure reveals that the autoinhibitory module is formed predominantly by the hydrophobic packing of helices from the N-terminal (HI-1, HI-2) and C-terminal (114, 115) inhibitory sequences, along with H1 of the intervening DNA binding ETS domain. The intramolecular interactions made by HI-1 in Ets-1DeltaN301 are similar to the intermolecular contacts observed in the crystal structure of an Ets-1DeltaN300 dimer, confirming that the latter represents a domain-swapped species. N-15 relaxation studies demonstrate that the backbone of the N-terminal inhibitory sequence is mobile on the nanosecond-picosecond and millisecond-microsecond time scales. Furthermore, hydrogen exchange measurements reveal that amide protons in helices HI-I and HI-2 exchange with water at rates only similar to15- and similar to75-fold slower, respectively, than predicted for an unfolded polypeptide. These findings indicate that inhibitory helices are only marginally stable even in the absence of DNA. The energetic coupling of DNA binding with the facile unfolding of the labile HI-1 provides a mechanism for modulating Ets-1 DNA binding activity via protein partnerships, post-translational modifications, or mutations. Ets-1 autoinhibition illustrates how conformational equilibria within structural domains can regulate macromolecular interactions.}, keywords = {BACKBONE DYNAMICS, CHEMICAL-EXCHANGE, DIPOLAR COUPLINGS, Ets-1, GROUP HYDROGEN-EXCHANGE, HIGH-RESOLUTION, MURINE, N-15 NMR RELAXATION, POINTED DOMAIN, SECONDARY STRUCTURE, SIDE-CHAINS}, isbn = {0021-9258}, url = {://000227332700099}, author = {Lee, G. M. and Donaldson, L. W. and Pufall, M. A. and Kang, H. S. and Pot, I. and Graves, B. J. and McIntosh, L. P.} } @article {4780, title = {Analysis of the dynamic properties of Bacillus circulans xylanase upon formation of a covalent glycosyl-enzyme intermediate}, journal = {Protein Science}, volume = {9}, number = {3}, year = {2000}, note = {ISI Document Delivery No.: 295XWTimes Cited: 16Cited Reference Count: 56}, month = {Mar}, pages = {512-524}, type = {Article}, abstract = {NMR spectroscopy was used to search for mechanistically significant differences in the local mobility of the main-chain amides of Bacillus circulans xylanase (BCX) in its native and catalytically competent covalent glycosyl-enzyme intermediate states. N-15 T-1, T-2, and N-15{H-1} NOE values were measured for similar to 120 out of 178 peptide groups in both the apo form of the protein and in BCX covalently modified at position Glu78 with a mechanism-based 2-deoxy-2-fluoro-beta-xylobioside inactivator. Employing the model-free formalism of Lipari and Szabo, the measured relaxation parameters were used to calculate a global correlation time ( tau(m)) for the protein in each form (9.2 +/- 0.2 ns for apo-BCX; 9.8 +/- 0.3 ns for the modified protein), as well as individual order parameters for the main-chain NH bond vectors. Average values of the order parameters for the protein in the apo and complexed forms were S-2 = 0.86 +/- 0.04 and S-2 = 0.91 +/- 0.04, respectively. No correlation is observed between these order parameters and the secondary structure, solvent accessibility, or hydrogen bonding patterns of amides in either form of the protein. These results demonstrate that the backbone of BCX is well ordered in both states and that formation of the,glycosyl-enzyme intermediate leads to little change, in any, in the dynamic properties of BCX on the time scales sampled by N-15-NMR relaxation measurements.}, keywords = {ACTIVE-SITE NUCLEOPHILE, ANISOTROPIC ROTATIONAL, BACKBONE DYNAMICS, BINDING, BURIED NEUTRAL HISTIDINE, DIFFUSION, glucanase, GLYCOSYL-ENZYME INTERMEDIATE, MAGNETIC-RESONANCE RELAXATION, MODEL-FREE APPROACH, N-15 NMR RELAXATION, NMR, order parameter, PROTEIN, PROTEINS, relaxation dynamics, SIDE-CHAIN RESONANCES, STRUCTURE}, isbn = {0961-8368}, url = {://000085994800009}, author = {Connelly, G. P. and Withers, S. G. and McIntosh, L. P.} }