5 results on '"Driggers, Camden M."'
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2. Ligand-mediated Structural Dynamics of a Mammalian Pancreatic K ATP Channel.
- Author
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Sung MW, Driggers CM, Mostofian B, Russo JD, Patton BL, Zuckerman DM, and Shyng SL
- Subjects
- Adenosine Triphosphate metabolism, Humans, Ligands, Pancreas, Protein Conformation, KATP Channels chemistry
- Abstract
Regulation of pancreatic K
ATP channels involves orchestrated interactions of their subunits, Kir6.2 and SUR1, and ligands. Previously we reported KATP channel cryo-EM structures in the presence and absence of pharmacological inhibitors and ATP, focusing on the mechanisms by which inhibitors act as pharmacological chaperones of KATP channels (Martin et al., 2019). Here we analyzed the same cryo-EM datasets with a focus on channel conformational dynamics to elucidate structural correlates pertinent to ligand interactions and channel gating. We found pharmacological inhibitors and ATP enrich a channel conformation in which the Kir6.2 cytoplasmic domain is closely associated with the transmembrane domain, while depleting one where the Kir6.2 cytoplasmic domain is extended away into the cytoplasm. This conformational change remodels a network of intra- and inter-subunit interactions as well as the ATP and PIP2 binding pockets. The structures resolved key contacts between the distal N-terminus of Kir6.2 and SUR1's ABC module involving residues implicated in channel function and showed a SUR1 residue, K134, participates in PIP2 binding. Molecular dynamics simulations revealed two Kir6.2 residues, K39 and R54, that mediate both ATP and PIP2 binding, suggesting a mechanism for competitive gating by ATP and PIP2 ., Competing Interests: Competing interests The authors declare that they have no competing financial or non-financial interests with the contents of this article., (Copyright © 2022 The Author(s). Published by Elsevier Ltd.. All rights reserved.)- Published
- 2022
- Full Text
- View/download PDF
3. Structure-Based Insights into the Role of the Cys-Tyr Crosslink and Inhibitor Recognition by Mammalian Cysteine Dioxygenase.
- Author
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Driggers CM, Kean KM, Hirschberger LL, Cooley RB, Stipanuk MH, and Karplus PA
- Subjects
- Animals, Crystallography, X-Ray, Cysteine genetics, Cysteine metabolism, Cysteine Dioxygenase genetics, Mammals, Models, Molecular, Mutant Proteins chemistry, Mutant Proteins genetics, Mutant Proteins metabolism, Protein Binding, Protein Conformation, Tyrosine genetics, Tyrosine metabolism, Cysteine Dioxygenase chemistry, Cysteine Dioxygenase metabolism, Enzyme Inhibitors metabolism
- Abstract
In mammals, the non-heme iron enzyme cysteine dioxygenase (CDO) helps regulate Cys levels through converting Cys to Cys sulfinic acid. Its activity is in part modulated by the formation of a Cys93-Tyr157 crosslink that increases its catalytic efficiency over 10-fold. Here, 21 high-resolution mammalian CDO structures are used to gain insight into how the Cys-Tyr crosslink promotes activity and how select competitive inhibitors bind. Crystal structures of crosslink-deficient C93A and Y157F variants reveal similar ~1.0-Å shifts in the side chain of residue 157, and both variant structures have a new chloride ion coordinating the active site iron. Cys binding is also different from wild-type CDO, and no Cys-persulfenate forms in the C93A or Y157F active sites at pH6.2 or 8.0. We conclude that the crosslink enhances activity by positioning the Tyr157 hydroxyl to enable proper Cys binding, proper oxygen binding, and optimal chemistry. In addition, structures are presented for homocysteine (Hcy), D-Cys, thiosulfate, and azide bound as competitive inhibitors. The observed binding modes of Hcy and D-Cys clarify why they are not substrates, and the binding of azide shows that in contrast to what has been proposed, it does not bind in these crystals as a superoxide mimic., (Copyright © 2016 Elsevier Ltd. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
4. Cysteine dioxygenase structures from pH4 to 9: consistent cys-persulfenate formation at intermediate pH and a Cys-bound enzyme at higher pH.
- Author
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Driggers CM, Cooley RB, Sankaran B, Hirschberger LL, Stipanuk MH, and Karplus PA
- Subjects
- Animals, Catalytic Domain, Crystallography, X-Ray methods, Hydrogen-Ion Concentration, Iron metabolism, Protein Binding, Protein Conformation, Rats, X-Ray Diffraction methods, Cysteine analogs & derivatives, Cysteine chemistry, Cysteine metabolism, Cysteine Dioxygenase chemistry, Cysteine Dioxygenase metabolism
- Abstract
Mammalian cysteine dioxygenase (CDO) is a mononuclear non-heme iron protein that catalyzes the conversion of cysteine (Cys) to cysteine sulfinic acid by an unclarified mechanism. One structural study revealed that a Cys-persulfenate (or Cys-persulfenic acid) formed in the active site, but quantum mechanical calculations have been used to support arguments that it is not an energetically feasible reaction intermediate. Here, we report a series of high-resolution structures of CDO soaked with Cys at pH values from 4 to 9. Cys binding is minimal at pH≤5 and persulfenate formation is consistently seen at pH values between 5.5 and 7. Also, a structure determined using laboratory-based X-ray diffraction shows that the persulfenate, with an apparent average O-O separation distance of ~1.8Å, is not an artifact of synchrotron radiation. At pH≥8, the active-site iron shifts from 4- to 5-coordinate, and Cys soaks reveal a complex with Cys, but no dioxygen, bound. This 'Cys-only' complex differs in detail from a previously published 'Cys-only' complex, which we reevaluate and conclude is not reliable. The high-resolution structures presented here do not resolve the CDO mechanism but do imply that an iron-bound persulfenate (or persulfenic acid) is energetically accessible in the CDO active site, and that CDO active-site chemistry in the crystals is influenced by protonation/deprotonation events with effective pKa values near ~5.5 and ~7.5 that influence Cys binding and oxygen binding/reactivity, respectively. Furthermore, this work provides reliable ligand-bound models for guiding future mechanistic considerations., (Copyright © 2013 Elsevier Ltd. All rights reserved.)
- Published
- 2013
- Full Text
- View/download PDF
5. Community-wide assessment of protein-interface modeling suggests improvements to design methodology.
- Author
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Fleishman SJ, Whitehead TA, Strauch EM, Corn JE, Qin S, Zhou HX, Mitchell JC, Demerdash ON, Takeda-Shitaka M, Terashi G, Moal IH, Li X, Bates PA, Zacharias M, Park H, Ko JS, Lee H, Seok C, Bourquard T, Bernauer J, Poupon A, Azé J, Soner S, Ovali SK, Ozbek P, Tal NB, Haliloglu T, Hwang H, Vreven T, Pierce BG, Weng Z, Pérez-Cano L, Pons C, Fernández-Recio J, Jiang F, Yang F, Gong X, Cao L, Xu X, Liu B, Wang P, Li C, Wang C, Robert CH, Guharoy M, Liu S, Huang Y, Li L, Guo D, Chen Y, Xiao Y, London N, Itzhaki Z, Schueler-Furman O, Inbar Y, Potapov V, Cohen M, Schreiber G, Tsuchiya Y, Kanamori E, Standley DM, Nakamura H, Kinoshita K, Driggers CM, Hall RG, Morgan JL, Hsu VL, Zhan J, Yang Y, Zhou Y, Kastritis PL, Bonvin AM, Zhang W, Camacho CJ, Kilambi KP, Sircar A, Gray JJ, Ohue M, Uchikoga N, Matsuzaki Y, Ishida T, Akiyama Y, Khashan R, Bush S, Fouches D, Tropsha A, Esquivel-Rodríguez J, Kihara D, Stranges PB, Jacak R, Kuhlman B, Huang SY, Zou X, Wodak SJ, Janin J, and Baker D
- Subjects
- Binding Sites, Protein Binding, Models, Molecular, Proteins chemistry
- Abstract
The CAPRI (Critical Assessment of Predicted Interactions) and CASP (Critical Assessment of protein Structure Prediction) experiments have demonstrated the power of community-wide tests of methodology in assessing the current state of the art and spurring progress in the very challenging areas of protein docking and structure prediction. We sought to bring the power of community-wide experiments to bear on a very challenging protein design problem that provides a complementary but equally fundamental test of current understanding of protein-binding thermodynamics. We have generated a number of designed protein-protein interfaces with very favorable computed binding energies but which do not appear to be formed in experiments, suggesting that there may be important physical chemistry missing in the energy calculations. A total of 28 research groups took up the challenge of determining what is missing: we provided structures of 87 designed complexes and 120 naturally occurring complexes and asked participants to identify energetic contributions and/or structural features that distinguish between the two sets. The community found that electrostatics and solvation terms partially distinguish the designs from the natural complexes, largely due to the nonpolar character of the designed interactions. Beyond this polarity difference, the community found that the designed binding surfaces were, on average, structurally less embedded in the designed monomers, suggesting that backbone conformational rigidity at the designed surface is important for realization of the designed function. These results can be used to improve computational design strategies, but there is still much to be learned; for example, one designed complex, which does form in experiments, was classified by all metrics as a nonbinder., (Copyright © 2011 Elsevier Ltd. All rights reserved.)
- Published
- 2011
- Full Text
- View/download PDF
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