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Manoharan GB, Laurini C, Bottone S, Ben Fredj N, Abankwa DK. K-Ras Binds Calmodulin-Related Centrin1 with Potential Implications for K-Ras Driven Cancer Cell Stemness. Cancers (Basel) 2023; 15:3087. [PMID: 37370697 DOI: 10.3390/cancers15123087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/30/2023] [Accepted: 06/05/2023] [Indexed: 06/29/2023] Open
Abstract
Recent data suggest that K-Ras4B (hereafter K-Ras) can drive cancer cell stemness via calmodulin (CaM)-dependent, non-canonical Wnt-signalling. Here we examined whether another Ca2+-binding protein, the CaM-related centrin1, binds to K-Ras and could mediate some K-Ras functions that were previously ascribed to CaM. While CaM and centrin1 appear to distinguish between peptides that were derived from their classical targets, they both bind to K-Ras in cells. Cellular BRET- and immunoprecipitation data suggest that CaM engages more with K-Ras than centrin1 and that the interaction with the C-terminal membrane anchor of K-Ras is sufficient for this. Surprisingly, binding of neither K-Ras nor its membrane anchor alone to CaM or centrin1 is sensitive to inhibition of prenylation. In support of an involvement of the G-domain of K-Ras in cellular complexes with these Ca2+-binding proteins, we find that oncogenic K-RasG12V displays increased engagement with both CaM and centrin1. This is abrogated by addition of the D38A effector-site mutation, suggesting that K-RasG12V is held together with CaM or centrin1 in complexes with effectors. When treated with CaM inhibitors, the BRET-interaction of K-RasG12V with centrin1 was also disrupted in the low micromolar range, comparable to that with CaM. While CaM predominates in regulating functional membrane anchorage of K-Ras, it has a very similar co-distribution with centrin1 on mitotic organelles. Given these results, a significant overlap of the CaM- and centrin1-dependent functions of K-Ras is suggested.
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Affiliation(s)
- Ganesh Babu Manoharan
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, L-4362 Esch-sur-Alzette, Luxembourg
| | - Christina Laurini
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, L-4362 Esch-sur-Alzette, Luxembourg
| | - Sara Bottone
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, L-4362 Esch-sur-Alzette, Luxembourg
| | - Nesrine Ben Fredj
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, L-4362 Esch-sur-Alzette, Luxembourg
| | - Daniel Kwaku Abankwa
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, L-4362 Esch-sur-Alzette, Luxembourg
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Manoharan GB, Okutachi S, Abankwa D. Potential of phenothiazines to synergistically block calmodulin and reactivate PP2A in cancer cells. PLoS One 2022; 17:e0268635. [PMID: 35617282 PMCID: PMC9135253 DOI: 10.1371/journal.pone.0268635] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 05/04/2022] [Indexed: 11/19/2022] Open
Abstract
Phenothiazines (PTZ) were developed as inhibitors of monoamine neurotransmitter receptors, notably dopamine receptors. Because of this activity they have been used for decades as antipsychotic drugs. In addition, they possess significant anti-cancer properties and several attempts for their repurposing were made. However, their incompletely understood polypharmacology is challenging. Here we examined the potential of the PTZ fluphenazine (Flu) and its mustard derivative (Flu-M) to synergistically act on two cancer associated targets, calmodulin (CaM) and the tumor suppressor protein phosphatase 2A (PP2A). Both proteins are known to modulate the Ras- and MAPK-pathway, cell viability and features of cancer cell stemness. Consistently, we show that the combination of a CaM inhibitor and the PP2A activator DT-061 synergistically inhibited the 3D-spheroid formation of MDA-MB-231 (K-Ras-G13D), NCI-H358 (K-Ras-G12C) and A375 (B-raf-V600E) cancer cells, and increased apoptosis in MDA-MB-231. We reasoned that these activities remain combined in PTZ, which were the starting point for PP2A activator development, while several PTZ are known CaM inhibitors. We show that both Flu and Flu-M retained CaM inhibitory activity in vitro and in cells, with a higher potency of the mustard derivative in cells. In line with the CaM dependence of Ras plasma membrane organization, the mustard derivative potently reduced the functional membrane organization of oncogenic Ras, while DT-061 had a negligible effect. Like DT-061, both PTZ potently decreased c-MYC levels, a hallmark of PP2A activation. Benchmarking against the KRAS-G12C specific inhibitor AMG-510 in MIA PaCa-2 cells revealed a higher potency of Flu-M than combinations of DT-061 and a CaM inhibitor on MAPK-output and a strong effect on cell proliferation. While our study is limited, our results suggest that improved PTZ derivatives that retain both, their CaM inhibitory and PP2A activating properties, but have lost their neurological side-effects, may be interesting to pursue further as anti-cancer agents.
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Affiliation(s)
- Ganesh Babu Manoharan
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Sunday Okutachi
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Daniel Abankwa
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
- * E-mail:
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Okutachi S, Manoharan GB, Kiriazis A, Laurini C, Catillon M, McCormick F, Yli-Kauhaluoma J, Abankwa D. A Covalent Calmodulin Inhibitor as a Tool to Study Cellular Mechanisms of K-Ras-Driven Stemness. Front Cell Dev Biol 2021; 9:665673. [PMID: 34307350 PMCID: PMC8296985 DOI: 10.3389/fcell.2021.665673] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2021] [Accepted: 06/04/2021] [Indexed: 11/23/2022] Open
Abstract
Recently, the highly mutated oncoprotein K-Ras4B (hereafter K-Ras) was shown to drive cancer cell stemness in conjunction with calmodulin (CaM). We previously showed that the covalent CaM inhibitor ophiobolin A (OphA) can potently inhibit K-Ras stemness activity. However, OphA, a fungus-derived natural product, exhibits an unspecific, broad toxicity across all phyla. Here we identified a less toxic, functional analog of OphA that can efficiently inactivate CaM by covalent inhibition. We analyzed a small series of benzazulenones, which bear some structural similarity to OphA and can be synthesized in only six steps. We identified the formyl aminobenzazulenone 1, here named Calmirasone1, as a novel and potent covalent CaM inhibitor. Calmirasone1 has a 4-fold increased affinity for CaM as compared to OphA and was active against K-Ras in cells within minutes, as compared to hours required by OphA. Calmirasone1 displayed a 2.5–4.5-fold higher selectivity for KRAS over BRAF mutant 3D spheroid growth than OphA, suggesting improved relative on-target activity. Importantly, Calmirasone1 has a 40–260-fold lower unspecific toxic effect on HRAS mutant cells, while it reaches almost 50% of the activity of novel K-RasG12C specific inhibitors in 3D spheroid assays. Our results suggest that Calmirasone1 can serve as a new tool compound to further investigate the cancer cell biology of the K-Ras and CaM associated stemness activities.
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Affiliation(s)
- Sunday Okutachi
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Ganesh Babu Manoharan
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Alexandros Kiriazis
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Christina Laurini
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Marie Catillon
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Frank McCormick
- Helen Diller Family Comprehensive Cancer Center, University of California, San Francisco, San Francisco, CA, United States.,Frederick National Laboratory for Cancer Research, Cancer Research Technology Program, Leidos Biomedical Research, Inc., National Cancer Institute RAS Initiative, Frederick, MD, United States
| | - Jari Yli-Kauhaluoma
- Drug Research Program, Division of Pharmaceutical Chemistry and Technology, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
| | - Daniel Abankwa
- Cancer Cell Biology and Drug Discovery Group, Department of Life Sciences and Medicine, University of Luxembourg, Esch-sur-Alzette, Luxembourg
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Abstract
Intracellular Ca2+ is normally maintained at submicromolar levels but increases during many forms of cellular stimulation. This increased Ca2+ binds to receptor proteins such as calmodulin (CaM) and alters the cell's metabolism and physiology. Calcium-CaM binds to target proteins and alters their function in such a way as to transduce the Ca2+ signal. Calcium-free or apocalmodulin (ApoCaM) binds to other proteins and has other specific effects. Apocalmodulin has roles in the cell that apparently do not require the ability to bind Ca2+ at all, and these roles appear to be essential for life. Apocalmodulin differs from Ca2+-CaM in its tertiary structure. It binds target proteins differently, utilizing different binding motifs such as the IQ motif and noncontiguous binding sites. Other kinds of binding potentially await discovery. The ApoCaM-binding proteins are a diverse group of at least 15 proteins including enzymes, actin-binding proteins, as well as cytoskeletal and other membrane proteins, including receptors and ion channels. Much of the cellular CaM is bound in a Ca2+-independent manner to membrane structures within the cell, and the proportion bound changes with cell growth and density, suggesting it may be a storage form. Apocalmodulin remains tightly bound to other proteins as subunits and probably hastens the response of these proteins to Ca2+. The overall picture that emerges is that CaM cycles between its Ca2+-bound and Ca2+-free states and in each state binds to different proteins and performs essential functions. Although much of the research focus has been on the roles of Ca2+-CaM, the roles of ApoCaM are equally vital but less well understood.
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Affiliation(s)
- L A Jurado
- Department of Biochemistry, University of Tennessee, Memphis, Tennessee, USA
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Kong Au T, Chow Leung P. Identification of the binding and inhibition sites in the calmodulin molecule for ophiobolin A by site-directed mutagenesis. PLANT PHYSIOLOGY 1998; 118:965-73. [PMID: 9808741 PMCID: PMC34807 DOI: 10.1104/pp.118.3.965] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Ophiobolin A, a fungal toxin that affects maize and rice, has previously been shown to inhibit calmodulin by reacting with the lysine (Lys) residues in the calmodulin. In the present study we mutated Lys-75, Lys-77, and Lys-148 in the calmodulin molecule by site-directed mutagenesis, either by deleting them or by changing them to glutamine or arginine. We found that each of these three Lys residues could bind one molecule of ophiobolin A. Normally, only Lys-75 and Lys-148 bind ophiobolin A. Lys-77 seemed to be blocked by the binding of ophiobolin A to Lys-75. Lys-75 is the primary binding site and is responsible for all of the inhibition of ophiobolin A. When Lys-75 was removed, Lys-77 could then react with ophiobolin A to produce inhibition. Lys-148 was shown to be a binding site but not an inhibition site. The Lys-75 mutants were partially resistant to ophiobolin A. When both Lys 75 and Lys-77 or all three Lys residues were mutated, the resulting calmodulins were very resistant to ophiobolin A. Furthermore, Lys residues added in positions 86 and/or 143 (which are highly conserved in plant calmodulins) did not react with ophiobolin A. None of the mutations seemed to affect the properties of calmodulin. These results show that ophiobolin A reacts quite specifically with calmodulin.
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Affiliation(s)
- T Kong Au
- Department of Zoology, The University of Hong Kong, Pokfulam Road, Hong Kong
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Leclerc L'Hostis E, Leclerc L, Haiech J, Poyart C, Marden MC. Heme-CO binding to tryptophan-containing calmodulin mutants. BIOCHIMICA ET BIOPHYSICA ACTA 1996; 1313:209-16. [PMID: 8898856 DOI: 10.1016/0167-4889(96)00091-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The binding of heme-CO to genetically engineered calmodulin containing a single tryptophan residue has been studied. A tryptophan residue was integrated at one of five positions: 26 or 62 of the N-terminal, 81 in the central helix, or 99 or 135 of the C-terminal. As for the wild type, the mutant calmodulins bind four molecules of heme-CO with an average affinity of 1 microM. (i) Homotropic effect. The quenching of the tryptophan fluorescence by energy transfer to the hemes indicates that there is no preference between the N- or C-terminal pockets for heme binding. The quenching is less than expected for a binomial distribution of four sites. This could indicate a lower energy transfer rate due to a specific orientation factor. The weak quenching as a function of the number of hemes bound may also reveal a cooperativity in the heme binding; the data can be simulated assuming two pairs of sites, where each pocket shows a cooperative binding for two hemes. (ii) Heterotropic effect. As observed for the wild type, addition of melittin does not displace the hemes from the mutant calmodulins; the affinity of heme-CO for the calmodulin.melittin complex is higher than that for calmodulin alone. The affinity of heme-CO for native calmodulin is also higher in the presence of trifluoperazine.
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Affiliation(s)
- E Leclerc L'Hostis
- Institut National de la Santé et de la Recherche Médicale, Unité 299, Hôpital de Bicêtre, Le Kremlin-Bicêtre, France
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Vandonselaar M, Hickie RA, Quail JW, Delbaere LT. Trifluoperazine-induced conformational change in Ca(2+)-calmodulin. NATURE STRUCTURAL BIOLOGY 1994; 1:795-801. [PMID: 7634090 DOI: 10.1038/nsb1194-795] [Citation(s) in RCA: 156] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Here we show that, as a consequence of binding the drug trifluoperazine, a major conformational movement occurs in Ca(2+)-calmodulin (CaM). The tertiary structure changes from an elongated dumb-bell, with exposed hydrophobic surfaces, to a compact globular form which can no longer interact with its target enzymes. It is likely that inactivation of Ca(2+)-CaM by trifluoperazine is due to this major tertiary-structural alteration in Ca(2+)-CaM, which is initiated and stabilized by drug binding. This conformational change is similar to that which occurs on the binding of Ca(2+)-CaM to target peptides. Two hydrophobic binding pockets, created by amino acid residues adjacent to Ca(2+)-coordinating residues, form the key recognition sites on Ca(2+)-CaM for both inhibitors and target enzymes.
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Affiliation(s)
- M Vandonselaar
- Department of Biochemistry, University of Saskatchewan, Saskatoon, Canada
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Cornelius AS, Reilly MP, Suzuki M, Asakura T, Horiuchi K. The mechanism of chlorpromazine-induced red blood cell swelling. GENERAL PHARMACOLOGY 1994; 25:205-10. [PMID: 8026707 DOI: 10.1016/0306-3623(94)90034-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
1. Chlorpromazine (CPZ)-induced red blood cell (RBC) swelling was investigated by determination of electrolyte, mean cell volume (MCV) and water content changes in CPZ-treated cells. 2. CPZ-induced RBC swelling is dose-, hematocrit- and pH-dependent, and is associated with a net increase in RBC monovalent cation and Cl- contents. 3. The partition coefficient (Kp) for the CPZ-RBC membrane interaction is pH dependent (Kp = 2500 at pH 7.8; Kp = 840 at pH 6.8). 4. Despite the pH dependence of Kp values an equal number of CPZ molecules is required to induce a 12% increase in MCV at pH 7.8 and 6.8.
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Affiliation(s)
- A S Cornelius
- Children's Hospital of Philadelphia, Department of Pediatrics, University of Pennsylvania School of Medicine 19104
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10
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Sharma Y, Gopalakrishna A, Balasubramanian D, Fairwell T, Krishna G. Studies on the interaction of the dye, stains-all, with individual calcium-binding domains of calmodulin. FEBS Lett 1993; 326:59-64. [PMID: 8325390 DOI: 10.1016/0014-5793(93)81761-n] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
We show that the calcium-mimic dye, Stains-all, is a convenient probe to study the structural features of the individual calcium-binding sites of calmodulin (CaM) and related calcium-binding proteins (CaBP). These peptides bind the dye in their calcium-binding sites, and induce a circular dichroism (CD) band in the bound dye in the 620 nm (J band) region, which is abolished upon the addition of calcium. Replacement of Asp by Asn in the + x position of the weaker calcium-binding site (site I of CaM) abolishes the dye binding, while the same change in the higher affinity site IV attenuates the binding of the dye and does not abolish it. Replacement of Tyr in site IV with Trp does not distort the geometry, although it increases the dye binding affinity.
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Affiliation(s)
- Y Sharma
- Centre for Cellular and Molecular Biology, Hyderabad, India
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11
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A calcium-sensitive fluorescent analog of calmodulin based on a novel calmodulin-binding fluorophore. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)30508-2] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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13
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Chin D, Brew K. Effects of modifying individual amino or carboxyl groups on the affinity of calmodulin for calcineurin. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84837-8] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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Zot HG, Puett D. An Enzymatically Active Cross-linked Complex of Calmodulin and Rabbit Skeletal Muscle Myosin Light Chain Kinase. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84866-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Ovádi J. Effects of drugs on calmodulin-mediated enzymatic actions. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 1989; 33:353-95. [PMID: 2687941 DOI: 10.1007/978-3-0348-9146-2_11] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
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17
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Wei Q, Jackson AE, Pervaiz S, Carraway KL, Lee EY, Puett D, Brew K. Effects of interaction with calcineurin on the reactivities of calmodulin lysines. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)77669-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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19
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Leung PC, Graves LM, Tipton CL. Characterization of the interaction of ophiobolin A and calmodulin. THE INTERNATIONAL JOURNAL OF BIOCHEMISTRY 1988; 20:1351-9. [PMID: 3243375 DOI: 10.1016/s0020-711x(98)90003-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
1. The fungal toxin ophiobolin A reacts with the epsilon-amino group of lysine to give a conjugated enamine produce with lambda max at 272 nm and a molar extinction of 19,200 per M/cm. 2. Bovine brain calmodulin reacts with ophiobolin A to give a lambda max at 272 nm. 3. One mol of calmodulin reacts with two moles of ophiobolin A. Reaction of 1 mol of ophiobolin A inactivates 1 mol of calmodulin. 4. Ophiobolin A-treated calmodulin is resistant to tryptic cleavage at lysine 77. 5. Ophiobolin A also inhibits Dictyostelium calmodulin which has glutamine instead of lysine at residue 77.
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Affiliation(s)
- P C Leung
- Department of Molecular Biology, Research Institute of Scripps Clinic, La Jolla, CA 92037
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Strynadka NC, James MN. Two trifluoperazine-binding sites on calmodulin predicted from comparative molecular modeling with troponin-C. Proteins 1988; 3:1-17. [PMID: 3375233 DOI: 10.1002/prot.340030102] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Among the known regulatory proteins that are conformationally sensitive to the binding of calcium ions, calmodulin and troponin-C have the greatest primary sequence homology. This observation has led to the conclusion that the most accurate predicted molecular model of calmodulin would be based on the X-ray crystallographic coordinates of the highly refined structure of turkey skeletal troponin-C. This paper describes the structure of calmodulin built from such a premise. The resulting molecular model was subjected to conjugate gradient energy minimization to remove unacceptable intramolecular non-bonded contacts. In the analysis of the resulting structure, many features of calmodulin, including the detailed conformation of the Ca2+-binding loops, the amino- and carboxy-terminal hydrophobic patches of the Ca2+-bound form, and the several clusters of acidic residues can be reconciled with much of the previously published solution data. Calmodulin is missing the N-terminal helix characteristic of troponin-C. The deletion of three residues from the central helical linker (denoted D/E in troponin-C) shortens the molecule and changes the orientation of the two domains of calmodulin by 60 degrees relative to those in troponin-C. The molecular model has been used to derive two possible binding sites for the antipsychotic drug trifluoperazine, a potent competitive inhibitor of calmodulin activity.
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Affiliation(s)
- N C Strynadka
- Medical Research Council of Canada Group in Protein Structure and Function, Department of Biochemistry, University of Alberta, Edmonton
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21
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Jackson AE, Harris TM, Puett D. Characterization of specific fluorenylmethyloxycarbonyl-containing calmodulin adducts by spectroscopy and phosphodiesterase stimulation. Protein J 1987. [DOI: 10.1007/bf00276736] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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