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Santolaria C, Velázquez D, Albacar M, Casamayor A, Ariño J. Functional mapping of the N-terminal region of the yeast moonlighting protein Sis2/Hal3 reveals crucial residues for Ppz1 regulation. FEBS J 2022; 289:7500-7518. [PMID: 35811492 PMCID: PMC10084417 DOI: 10.1111/febs.16572] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2022] [Revised: 06/15/2022] [Accepted: 07/05/2022] [Indexed: 01/14/2023]
Abstract
The function of the Saccharomyces cerevisiae Ppz1 phosphatase is controlled by its inhibitory subunit Hal3. Hal3 is a moonlighting protein, which associates with Cab3 to form a decarboxylase involved in the CoA biosynthetic pathway. Hal3 is composed by a conserved core PD region, required for both Ppz1 regulation and CoA biosynthesis, a long N-terminal extension, and an acidic C-terminal tail. Cab3 has a similar structure, but it is not a Ppz1 inhibitor. We show here that deletion or specific mutations in a short region of the N-terminal extension of Hal3 compromise its function as a Ppz1 inhibitor in vivo and in vitro without negatively affecting its ability to interact with the phosphatase. This study defines a R-K-X(3) -VTFS- sequence whose presence explains the unexpected ability of Cab3 (but not Hal3) to regulate Ppz1 function in Candida albicans. This sequence is conserved in a subset of fungi and it could serve to estimate the relevance of Hal3 or Cab3 proteins in regulating fungal Ppz enzymes. We also show that the removal of the motif moderately affects both Ppz1 intracellular relocalization and counteraction of toxicity in cells overexpressing the phosphatase. Thus, our work contributes to our understanding of the regulation of Ppz phosphatases, which are determinants for virulence in some pathogenic fungi.
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Affiliation(s)
- Carlos Santolaria
- Institut de Biotecnologia i Biomedicina & Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | | | - Marcel Albacar
- Institut de Biotecnologia i Biomedicina & Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | - Antonio Casamayor
- Institut de Biotecnologia i Biomedicina & Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | - Joaquín Ariño
- Institut de Biotecnologia i Biomedicina & Departament de Bioquímica i Biologia Molecular, Universitat Autònoma de Barcelona, Cerdanyola del Vallès, Spain
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2
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Buneeva OA, Kopylov AT, Medvedev AE. [The key role of the regulatory 19S subunit in changes in the brain proteasome subproteome induced by the neuroprotector isatin]. Biomed Khim 2022; 68:250-262. [PMID: 36005843 DOI: 10.18097/pbmc20226804250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Isatin (indole-2,3-dione) is an endogenous regulator exhibiting various effects mediated by numerous isatin-binding proteins localized in different compartments of cells of the brain and peripheral tissues. It attenuates manifestations of experimental parkinsonism induced by administration of the MPTP neurotoxin and reduces the movement disorders characteristic of this disease. The molecular mechanisms of the neuroprotective action of isatin include its direct interaction with proteasomes, intracellular supramolecular complexes responsible for the targeted elimination of proteins. Incubation of fractions of 26S and 20S rabbit brain proteasomes, containing the whole spectrum of proteasomal subunits, as well as a number of proteasome-associated proteins, with isatin (100 μM) had a significant impact on the profile of released proteins. In the case of 26S proteasomes containing, in addition to the core part (20S proteasome), 19S regulatory subparticles, incubation with isatin resulted in a more than threefold increase in the number of dissociated proteins. In the case of 20S proteasomes (containing only the 20S core particle), incubation with isatin resulted in a significant decrease in the number of dissociated proteins compared to the control. Our results indicate an important role of the regulatory 19S subunit components in the formation of the proteasome subproteome and the sensitivity of these supramolecular complexes to isatin.
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Affiliation(s)
- O A Buneeva
- Institute of Biomedical Chemistry, Moscow, Russia
| | - A T Kopylov
- Institute of Biomedical Chemistry, Moscow, Russia
| | - A E Medvedev
- Institute of Biomedical Chemistry, Moscow, Russia
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3
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Autry JM, Svensson B, Carlson SF, Chen Z, Cornea RL, Thomas DD, Valberg SJ. Sarcoplasmic Reticulum from Horse Gluteal Muscle Is Poised for Enhanced Calcium Transport. Vet Sci 2021; 8:289. [PMID: 34941816 DOI: 10.3390/vetsci8120289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/02/2021] [Accepted: 11/17/2021] [Indexed: 11/16/2022] Open
Abstract
We have analyzed the enzymatic activity of the sarcoplasmic reticulum (SR) Ca2+-transporting ATPase (SERCA) from the horse gluteal muscle. Horses are bred for peak athletic performance yet exhibit a high incidence of exertional rhabdomyolysis, with elevated levels of cytosolic Ca2+ proposed as a correlative linkage. We recently reported an improved protocol for isolating SR vesicles from horse muscle; these horse SR vesicles contain an abundant level of SERCA and only trace-levels of sarcolipin (SLN), the inhibitory peptide subunit of SERCA in mammalian fast-twitch skeletal muscle. Here, we report that the in vitro Ca2+ transport rate of horse SR vesicles is 2.3 ± 0.7-fold greater than rabbit SR vesicles, which express close to equimolar levels of SERCA and SLN. This suggests that horse myofibers exhibit an enhanced SR Ca2+ transport rate and increased luminal Ca2+ stores in vivo. Using the densitometry of Coomassie-stained SDS-PAGE gels, we determined that horse SR vesicles express an abundant level of the luminal SR Ca2+ storage protein calsequestrin (CASQ), with a CASQ-to-SERCA ratio about double that in rabbit SR vesicles. Thus, we propose that SR Ca2+ cycling in horse myofibers is enhanced by a reduced SLN inhibition of SERCA and by an abundant expression of CASQ. Together, these results suggest that horse muscle contractility and susceptibility to exertional rhabdomyolysis are promoted by enhanced SR Ca2+ uptake and luminal Ca2+ storage.
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Taylor SS, Wu J, Bruystens JGH, Del Rio JC, Lu TW, Kornev AP, Ten Eyck LF. From structure to the dynamic regulation of a molecular switch: A journey over 3 decades. J Biol Chem 2021; 296:100746. [PMID: 33957122 PMCID: PMC8144671 DOI: 10.1016/j.jbc.2021.100746] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 04/16/2021] [Accepted: 04/30/2021] [Indexed: 12/14/2022] Open
Abstract
It is difficult to imagine where the signaling community would be today without the Protein Data Bank. This visionary resource, established in the 1970s, has been an essential partner for sharing information between academics and industry for over 3 decades. We describe here the history of our journey with the protein kinases using cAMP-dependent protein kinase as a prototype. We summarize what we have learned since the first structure, published in 1991, why our journey is still ongoing, and why it has been essential to share our structural information. For regulation of kinase activity, we focus on the cAMP-binding protein kinase regulatory subunits. By exploring full-length macromolecular complexes, we discovered not only allostery but also an essential motif originally attributed to crystal packing. Massive genomic data on disease mutations allows us to now revisit crystal packing as a treasure chest of possible protein:protein interfaces where the biological significance and disease relevance can be validated. It provides a new window into exploring dynamic intrinsically disordered regions that previously were deleted, ignored, or attributed to crystal packing. Merging of crystallography with cryo-electron microscopy, cryo-electron tomography, NMR, and millisecond molecular dynamics simulations is opening a new world for the signaling community where those structure coordinates, deposited in the Protein Data Bank, are just a starting point!
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Affiliation(s)
- Susan S Taylor
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA; Department of Chemistry and Biochemistry, University of California at San Diego, San Diego, California, USA.
| | - Jian Wu
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Jessica G H Bruystens
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Jason C Del Rio
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Tsan-Wen Lu
- Department of Biochemistry and Biophysics, University of California at San Francisco, San Francisco, California, USA
| | - Alexandr P Kornev
- Department of Pharmacology, University of California at San Diego, San Diego, California, USA
| | - Lynn F Ten Eyck
- Department of Chemistry and Biochemistry, University of California at San Diego, San Diego, California, USA; San Diego Supercomputer Center, University of California at San Diego, San Diego, California, USA
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5
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Plank M, Berti M, Loewith R. Phosphoproteomic Effects of Acute Depletion of PP2A Regulatory Subunit Cdc55. Proteomics 2020; 21:e2000166. [PMID: 32970932 DOI: 10.1002/pmic.202000166] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Revised: 09/15/2020] [Indexed: 11/08/2022]
Abstract
Protein phosphatase regulatory subunits are increasingly recognized as promising drug targets. In the absence of an existing drug, inducible degradation provides a means of predicting candidate targets. Here auxin-inducible degradation of Saccharomyces cerevisiae PP2A regulatory subunit Cdc55 in combination with quantitative phosphoproteomics is employed. A prevalence of hyperphosphorylated phosphopeptides indicates that the approach successfully identified direct PP2ACdc55 targets. PRM follow up of data-dependent acquisition results confirmed that vacuolar amino acid transporters are among the proteins most strongly affected by Cdc55 depletion.
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Affiliation(s)
- Michael Plank
- Department of Molecular Biology, University of Geneva, Geneva, CH-1211, Switzerland.,National Centre of Competence in Research-Chemical Biology, University of Geneva, Geneva, CH-1211, Switzerland
| | - Marina Berti
- Department of Molecular Biology, University of Geneva, Geneva, CH-1211, Switzerland
| | - Robbie Loewith
- Department of Molecular Biology, University of Geneva, Geneva, CH-1211, Switzerland.,National Centre of Competence in Research-Chemical Biology, University of Geneva, Geneva, CH-1211, Switzerland
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Ito Y, Hart JR, Vogt PK. Isoform-specific activities of the regulatory subunits of phosphatidylinositol 3-kinases - potentially novel therapeutic targets. Expert Opin Ther Targets 2018; 22:869-877. [PMID: 30205700 DOI: 10.1080/14728222.2018.1522302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
INTRODUCTION The main regulatory subunits of Class IA phosphatidylinositol 3-kinase (PI3K), p85α and p85β, initiate diverse cellular activities independent of binding to the catalytic subunit p110. Several of these signaling processes directly or indirectly contribute to a regulation of PI3K and could become targets for therapeutic efforts. Areas covered: This review will highlight two general areas of p85 activity: (1) direct interaction with regulatory proteins and with determinants of the cytoskeleton, and (2) a genetic analysis by deletion and domain switches identifying new functions for p85 domains. Expert Opinion: Isoform-specific activities of regulatory subunits have long been at the periphery of the PI3K field. Our understanding of these unique functions of the regulatory subunits is fragmentary and raises many important questions. At this time, there is insufficient information to translate this knowledge into the clinic, but some tempting targets have emerged that could move the field forward with the help of novel technologies in drug design and identification.
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Affiliation(s)
- Yoshihiro Ito
- a Department of Molecular Medicine , The Scripps Research Institute , La Jolla , CA , USA
| | - Jonathan R Hart
- a Department of Molecular Medicine , The Scripps Research Institute , La Jolla , CA , USA
| | - Peter K Vogt
- a Department of Molecular Medicine , The Scripps Research Institute , La Jolla , CA , USA
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Ishibashi K, Ishii K, Sugiyama G, Kamata YU, Suzuki A, Kumamaru W, Ohyama Y, Nakano H, Kiyoshima T, Sumida T, Yamada T, Mori Y. Regulation of β-Catenin Phosphorylation by PR55β in Adenoid Cystic Carcinoma. Cancer Genomics Proteomics 2018; 15:53-60. [PMID: 29275362 DOI: 10.21873/cgp.20064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2017] [Revised: 11/01/2017] [Accepted: 11/02/2017] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND/AIM Adenoid cystic carcinoma (AdCC) is a rare cancer of the salivary gland with high risk of recurrence and metastasis. Wnt signalling is critical for determining tumor grade in AdCC, as it regulates invasion and migration. β-catenin dephosphorylation plays an important role in the Wnt pathway, but its underlying molecular mechanism remains unclear. MATERIALS AND METHODS Because the regulatory subunits of protein phosphatase 2A (PP2A) drive Wnt signalling via target molecules, including β-catenin, we used qRT-PCR and immunoblot analysis to investigate the expression of these subunits in an AdCC cell line (ACCS) and a more aggressive subline (ACCS-M). RESULTS PR55β was highly expressed in ACCS-M, suggesting its functional importance. In addition, PR55β expression was associated with tumor grade, with ACCS-M exhibiting higher PR55β levels. More importantly, knockdown of PR55β in ACCS-M cells significantly reduced invasiveness and metastatic ability. Furthermore, dephosphorylation and total levels of β-catenin were dependent on PR55β in ACCS-M. Finally, we confirmed a correlation between PR55β staining intensity and histopathological type in human AdCC tissues. CONCLUSION Our study provides new insight into the interaction between PR55β and β-catenin and suggests that PR55β may be a target for the clinical treatment of AdCC.
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Affiliation(s)
- Kana Ishibashi
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Kotaro Ishii
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Goro Sugiyama
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Y U Kamata
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Azusa Suzuki
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Wataru Kumamaru
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yukiko Ohyama
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Hiroyuki Nakano
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Tamotsu Kiyoshima
- Laboratory of Oral Pathology, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Tomoki Sumida
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Tomohiro Yamada
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
| | - Yoshihide Mori
- Section of Oral and Maxillofacial Surgery, Division of Maxillofacial Diagnostic and Surgical Sciences, Faculty of Dental Science, Kyushu University, Fukuoka, Japan
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8
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Affiliation(s)
- Christine Beeton
- a Department of Molecular Physiology and Biophysics , Baylor College of Medicine , Houston , TX , USA
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9
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Satoh T, Toshimori T, Noda M, Uchiyama S, Kato K. Interaction mode between catalytic and regulatory subunits in glucosidase II involved in ER glycoprotein quality control. Protein Sci 2016; 25:2095-2101. [PMID: 27576940 DOI: 10.1002/pro.3031] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Revised: 08/28/2016] [Accepted: 08/29/2016] [Indexed: 12/18/2022]
Abstract
The glycoside hydrolase family 31 (GH31) α-glucosidases play vital roles in catabolic and regulated degradation, including the α-subunit of glucosidase II (GIIα), which catalyzes trimming of the terminal glucose residues of N-glycan in glycoprotein processing coupled with quality control in the endoplasmic reticulum (ER). Among the known GH31 enzymes, only GIIα functions with its binding partner, regulatory β-subunit (GIIβ), which harbors a lectin domain for substrate recognition. Although the structural data have been reported for GIIα and the GIIβ lectin domain, the interaction mode between GIIα and GIIβ remains unknown. Here, we determined the structure of a complex formed between GIIα and the GIIα-binding domain of GIIβ, thereby providing a structural basis underlying the functional extension of this unique GH31 enzyme.
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Affiliation(s)
- Tadashi Satoh
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan. .,JST, PRESTO, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan.
| | - Takayasu Toshimori
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan.,Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.,Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan
| | - Masanori Noda
- Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Susumu Uchiyama
- Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.,Department of Biotechnology, Graduate School of Engineering, Osaka University, 2-1 Yamadaoka, Suita, Osaka, 565-0871, Japan
| | - Koichi Kato
- Graduate School of Pharmaceutical Sciences, Nagoya City University, 3-1 Tanabe-dori, Mizuho-ku, Nagoya, 467-8603, Japan. .,Okazaki Institute for Integrative Bioscience, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan. .,Institute for Molecular Science, National Institutes of Natural Sciences, 5-1 Higashiyama, Myodaiji, Okazaki, Aichi, 444-8787, Japan.
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Abstract
This review focuses on the anxiety related to cyclic AMP/protein kinase A (PKA) signaling pathway that regulates stress responses. PKA regulates an array of diverse signals that interact with various neurotransmitter systems associated with alertness, mood, and acute and social anxiety-like states. Recent mouse studies support the involvement of the PKA pathway in common neuropsychiatric disorders characterized by heightened activation of the amygdala. The amygdala is critical for adaptive responses leading to fear learning and aberrant fear memory and its heightened activation is widely thought to underpin various anxiety disorders. Stress-induced plasticity within the amygdala is involved in the transition from normal vigilance responses to emotional reactivity, fear over-generalization, and deficits in fear inhibition resulting in pathological anxiety and conditions, such as panic and depression. Human studies of PKA signaling defects also report an increased incidence of psychiatric disorders, including anxiety, depression, bipolar disorder, learning disorders, and attention deficit hyperactivity disorder. We speculate that the PKA system is uniquely suited for selective, molecularly targeted intervention that may be proven effective in anxiolytic therapy.
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Affiliation(s)
- Margaret F. Keil
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
- *Correspondence: Margaret F. Keil, ; T. John Wu,
| | - George Briassoulis
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
- Department of Pediatric Intensive Care, University of Crete, Heraklion, Greece
| | - Constantine A. Stratakis
- Section on Endocrinology and Genetics, Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), National Institutes of Health (NIH), Bethesda, MD, USA
| | - T. John Wu
- Department of Obstetrics and Gynecology, Center for Neuroscience and Regenerative Medicine, Uniformed Services University of the Health Sciences, Bethesda, MD, USA
- *Correspondence: Margaret F. Keil, ; T. John Wu,
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Abstract
Ion channels function as multi-protein complexes made up of ion-conducting α-subunits and regulatory β-subunits. To detect, identify, and quantitate the regulatory β-subunits in functioning K(+) channel complexes, we have chemically derivatized peptide-toxins that specifically react with strategically placed cysteine residues in the channel complex. Two protein labeling approaches have been developed to derivatize the peptide-toxin, charybdotoxin, with hydrophilic and hydrophobic bismaleimides, and other molecular probes. Using these cysteine-reactive peptide-toxins, we have specifically targeted KCNQ1-KCNE1 K(+) channel complexes expressed in both Xenopus oocytes and mammalian cells. The modular design of the reagents should permit this approach to be applied to the many ion channel complexes involved in electrical excitability as well as salt and water homoeostasis.
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Petkowski JJ, Chruszcz M, Zimmerman MD, Zheng H, Skarina T, Onopriyenko O, Cymborowski MT, Koclega KD, Savchenko A, Edwards A, Minor W. Crystal structures of TM0549 and NE1324--two orthologs of E. coli AHAS isozyme III small regulatory subunit. Protein Sci 2007; 16:1360-7. [PMID: 17586771 PMCID: PMC2206681 DOI: 10.1110/ps.072793807] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 04/09/2007] [Accepted: 04/16/2007] [Indexed: 10/23/2022]
Abstract
Crystal structures of two orthologs of the regulatory subunit of acetohydroxyacid synthase III (AHAS, EC 2.2.1.6) from Thermotoga maritima (TM0549) and Nitrosomonas europea (NE1324) were determined by single-wavelength anomalous diffraction methods with the use of selenomethionine derivatives at 2.3 A and 2.5 A, respectively. TM0549 and NE1324 share the same fold, and in both proteins the polypeptide chain contains two separate domains of a similar size. Each protein contains a C-terminal domain with ferredoxin-type fold and an N-terminal ACT domain, of which the latter is characteristic for several proteins involved in amino acid metabolism. The ferredoxin domain is stabilized by a calcium ion in the crystal structure of NE1324 and by a Mg(H2O)(6)2+ ion in TM0549. Both TM0549 and NE1324 form dimeric assemblies in the crystal lattice.
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Affiliation(s)
- Janusz J Petkowski
- Department of Molecular Physiology and Biological Physics, University of Virginia, Charlottesville 22908, USA
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Zawadzki KM, Hamuro Y, Kim JS, Garrod S, Stranz DD, Taylor SS, Woods VL. Dissecting interdomain communication within cAPK regulatory subunit type IIbeta using enhanced amide hydrogen/deuterium exchange mass spectrometry (DXMS). Protein Sci 2003; 12:1980-90. [PMID: 12930997 PMCID: PMC2323995 DOI: 10.1110/ps.03166903] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
cAMP-dependent protein kinase (cAPK) is a heterotetramer containing a regulatory (R) subunit dimer bound to two catalytic (C) subunits and is involved in numerous cell signaling pathways. The C-subunit is activated allosterically when two cAMP molecules bind sequentially to the cAMP-binding domains, designated A and B (cAB-A and cAB-B, respectively). Each cAMP-binding domain contains a conserved Arg residue that is critical for high-affinity cAMP binding. Replacement of this Arg with Lys affects cAMP affinity, the structural integrity of the cAMP-binding domains, and cAPK activation. To better understand the local and long-range effects that the Arg-to-Lys mutation has on the dynamic properties of the R-subunit, the amide hydrogen/deuterium exchange in the RIIbeta subunit was probed by electrospray mass spectrometry. Mutant proteins containing the Arg-to-Lys substitution in either cAMP-binding domain were deuterated for various times and then, prior to mass spectrometry analysis, subjected to pepsin digestion to localize the deuterium incorporation. Mutation of this Arg in cAB-A (Arg230) causes an increase in amide hydrogen exchange throughout the mutated domain that is beyond the modest and localized effects of cAMP removal and is indicative of the importance of this Arg in domain organization. Mutation of Arg359 (cAB-B) leads to increased exchange in the adjacent cAB-A domain, particularly in the cAB-A domain C-helix that lies on top of the cAB-B domain and is believed to be functionally linked to the cAB-B domain. This interdomain communication appears to be a unidirectional pathway, as mutation of Arg230 in cAB-A does not effect dynamics of the cAB-B domain.
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Affiliation(s)
- Kerri M Zawadzki
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California 92093, USA
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14
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Abstract
The protein kinase A (PKA) is classified as type I or II depending on the association of the catalytic subunit with either the R(I) or R(II) regulatory subunits. Alterations in the levels of these regulatory subunits and PKA activity itself appear to affect cellular proliferation and tumorigenesis. We examined colorectal tumor specimens from 45 patients to investigate the potential role of cAMP-related signaling molecules in regulating tumorigenesis. Western blot analysis (PKA subunit protein levels) and in vitro kemptide phosphorylation assays (PKA catalytic subunit activity) were performed on human colorectal tumor tissue homogenates. R(I)beta protein levels were decreased 200% in ascending and 50% in descending colonic tumors compared to adjacent mucosa. R(II) protein levels were decreased 77% in descending colonic tumors but no change was observed in ascending colonic tumors compared to adjacent mucosa. PKA activity and the absolute amount of catalytic subunit protein in ascending and descending tumors were unchanged compared to adjacent mucosa. Differences in cAMP-related signaling molecules exist between neoplastic and normal colorectal tissues. These differences may not only serve as potential therapeutic targets for chemotherapeutic agents, but also lead to the identification of novel regulatory mechanisms involved in cellular proliferation and tumorigenesis.
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Affiliation(s)
- C C Carlson
- Department of Surgery, Medical College of Georgia, Augusta 30912, USA
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15
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Brostrom CO, Corbin JD, King CA, Krebs EG. Interaction of the subunits of adenosine 3':5'-cyclic monophosphate-dependent protein kinase of muscle. Proc Natl Acad Sci U S A 1971; 68:2444-7. [PMID: 4332811 PMCID: PMC389440 DOI: 10.1073/pnas.68.10.2444] [Citation(s) in RCA: 109] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Two cAMP-dependent protein kinases purified from rabbit skeletal muscle were shown to bind the same amount of cAMP per unit of enzyme activity at several concentrations of this nucleotide. A preparation containing both of these kinases was separated into catalytic (C) and regulatory (R) subunit fractions in the presence of cAMP, the regulatory subunit being obtained as an R.cAMP complex. Addition of increasing amounts of the R.cAMP complex to the holoenzyme (RC) increased the concentration of cAMP required for half-maximal activity of the enzyme. cAMP was liberated from the R.cAMP complex in the presence of added catalytic subunit in a reaction that was facilitated by Mg(2+), ATP, and warming. These findings are presented in support of a model for activation of the protein kinase by cAMP. The possibility that excess regulatory subunit may serve as a sink for intracellular cAMP is also discussed. It is shown that cAMP bound to the R subunit is not a substrate for the cAMP phosphodiesterase.
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