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Hikage F, Watanabe M, Sato T, Umetsu A, Tsugeno Y, Furuhashi M, Ohguro H. Simultaneous Effects of a Selective EP2 Agonist, Omidenepag, and a Rho-Associated Coiled-Coil Containing Protein Kinase Inhibitor, Ripasudil, on Human Orbital Fibroblasts. J Ocul Pharmacol Ther 2023; 39:439-448. [PMID: 37352418 DOI: 10.1089/jop.2023.0025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/25/2023] Open
Abstract
Purpose: To assess the combined effects of omidenepag (OMD), a selective EP2 agonist, and ripasudil (Rip), an inhibitor of rho-associated coiled-coil containing protein kinases, on the human orbital adipose tissue, two-dimensional (2D) or three-dimensional (3D) cultures of human orbital fibroblasts (HOFs) were employed. Methods: Cellular metabolic functions (2D), physical (3D), lipid staining (3D), and quantitative polymerase chain reaction for adipogenesis-related genes, PPARγ and AP2, and extracellular matrix (ECM) molecules, including collagen (COL)1, 4, and 6, and fibronectin (FN) (3D) were evaluated in the presence of OMD (100 nM) and/or Rip (10 μM). Results: Real-time metabolic analyses revealed that the adipogenic differentiation (DIF+) with OMD significantly shifted an energetic state toward energetic, whereas DIF+ with Rip significantly shifted that toward quiescent. In the case of both drugs upon DIF+, the metabolic effect of OMD was predominant. DIF+ induced enlargement and stiffed 3D spheroid with increased lipid staining and mRNA expression of adipogenesis-related genes, COL4 and COL6, and decreased the expression of COL1. In the presence of OMD and/or Rip to DIF+, (1) the sizes were further increased by Rip and the stiffness was significantly decreased by OMD or Rip and (2) COL4 or AP2 expression was substantially increased by OMD or Rip, respectively. Conclusion: The results presented herein indicate that the metabolic effects of OMD and Rip exerted opposing effects and the effects of OMD toward Ap2 and ECM expressions were distinct from those of Rip, but the effects of OMD toward the physical aspects and adipogenesis of the 3D cultured HOFs were similar to the effects of Rip.
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Affiliation(s)
- Fumihito Hikage
- Department of Ophthalmology, School of Medicine, Sapporo Medical University, Sapporo, Japan
| | - Megumi Watanabe
- Department of Ophthalmology, School of Medicine, Sapporo Medical University, Sapporo, Japan
| | - Tatsuya Sato
- Department of Cardiovascular, Renal and Metabolic Medicine, and School of Medicine, Sapporo Medical University, Sapporo, Japan
- Department of Cellular Physiology and Signal Transduction, School of Medicine, Sapporo Medical University, Sapporo, Japan
| | - Araya Umetsu
- Department of Ophthalmology, School of Medicine, Sapporo Medical University, Sapporo, Japan
| | - Yuri Tsugeno
- Department of Ophthalmology, School of Medicine, Sapporo Medical University, Sapporo, Japan
| | - Masato Furuhashi
- Department of Cardiovascular, Renal and Metabolic Medicine, and School of Medicine, Sapporo Medical University, Sapporo, Japan
| | - Hiroshi Ohguro
- Department of Ophthalmology, School of Medicine, Sapporo Medical University, Sapporo, Japan
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Alcala DB, Haldeman BD, Brizendine RK, Krenc AK, Baker JE, Rock RS, Cremo CR. Myosin light chain kinase steady-state kinetics: comparison of smooth muscle myosin II and nonmuscle myosin IIB as substrates. Cell Biochem Funct 2016; 34:469-474. [PMID: 27528075 DOI: 10.1002/cbf.3209] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2016] [Revised: 07/07/2016] [Accepted: 07/11/2016] [Indexed: 01/31/2023]
Abstract
Myosin light chain kinase (MLCK) phosphorylates S19 of the myosin regulatory light chain (RLC), which is required to activate myosin's ATPase activity and contraction. Smooth muscles are known to display plasticity in response to factors such as inflammation, developmental stage, or stress, which lead to differential expression of nonmuscle and smooth muscle isoforms. Here, we compare steady-state kinetics parameters for phosphorylation of different MLCK substrates: (1) nonmuscle RLC, (2) smooth muscle RLC, and heavy meromyosin subfragments of (3) nonmuscle myosin IIB, and (4) smooth muscle myosin II. We show that MLCK has a ~2-fold higher kcat for both smooth muscle myosin II substrates compared with nonmuscle myosin IIB substrates, whereas Km values were very similar. Myosin light chain kinase has a 1.6-fold and 1.5-fold higher specificity (kcat /Km ) for smooth versus nonmuscle-free RLC and heavy meromyosin, respectively, suggesting that differences in specificity are dictated by RLC sequences. Of the 10 non-identical RLC residues, we ruled out 7 as possible underlying causes of different MLCK kinetics. The remaining 3 residues were found to be surface exposed in the N-terminal half of the RLC, consistent with their importance in substrate recognition. These data are consistent with prior deletion/chimera studies and significantly add to understanding of MLCK myosin interactions. SIGNIFICANCE OF THE STUDY Phosphorylation of nonmuscle and smooth muscle myosin by myosin light chain kinase (MLCK) is required for activation of myosin's ATPase activity. In smooth muscles, nonmuscle myosin coexists with smooth muscle myosin, but the two myosins have very different chemo-mechanical properties relating to their ability to maintain force. Differences in specificity of MLCK for different myosin isoforms had not been previously investigated. We show that the MLCK prefers smooth muscle myosin by a significant factor. These data suggest that nonmuscle myosin is phosphorylated more slowly than smooth muscle myosin during a contraction cycle.
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Affiliation(s)
- Diego B Alcala
- Department of Pharmacology, University of Nevada Reno School of Medicine, Reno, Nevada, USA
| | - Brian D Haldeman
- Department of Pharmacology, University of Nevada Reno School of Medicine, Reno, Nevada, USA
| | - Richard K Brizendine
- Department of Pharmacology, University of Nevada Reno School of Medicine, Reno, Nevada, USA
| | - Agata K Krenc
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA
| | - Josh E Baker
- Department of Pharmacology, University of Nevada Reno School of Medicine, Reno, Nevada, USA
| | - Ronald S Rock
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, Illinois, USA
| | - Christine R Cremo
- Department of Pharmacology, University of Nevada Reno School of Medicine, Reno, Nevada, USA.
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3
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Stull JT, Kamm KE, Vandenboom R. Myosin light chain kinase and the role of myosin light chain phosphorylation in skeletal muscle. Arch Biochem Biophys 2011; 510:120-8. [PMID: 21284933 PMCID: PMC3101293 DOI: 10.1016/j.abb.2011.01.017] [Citation(s) in RCA: 124] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2010] [Revised: 01/24/2011] [Accepted: 01/24/2011] [Indexed: 10/18/2022]
Abstract
Skeletal muscle myosin light chain kinase (skMLCK) is a dedicated Ca(2+)/calmodulin-dependent serine-threonine protein kinase that phosphorylates the regulatory light chain (RLC) of sarcomeric myosin. It is expressed from the MYLK2 gene specifically in skeletal muscle fibers with most abundance in fast contracting muscles. Biochemically, activation occurs with Ca(2+) binding to calmodulin forming a (Ca(2+))(4)•calmodulin complex sufficient for activation with a diffusion limited, stoichiometric binding and displacement of a regulatory segment from skMLCK catalytic core. The N-terminal sequence of RLC then extends through the exposed catalytic cleft for Ser15 phosphorylation. Removal of Ca(2+) results in the slow dissociation of calmodulin and inactivation of skMLCK. Combined biochemical properties provide unique features for the physiological responsiveness of RLC phosphorylation, including (1) rapid activation of MLCK by Ca(2+)/calmodulin, (2) limiting kinase activity so phosphorylation is slower than contraction, (3) slow MLCK inactivation after relaxation and (4) much greater kinase activity relative to myosin light chain phosphatase (MLCP). SkMLCK phosphorylation of myosin RLC modulates mechanical aspects of vertebrate skeletal muscle function. In permeabilized skeletal muscle fibers, phosphorylation-mediated alterations in myosin structure increase the rate of force-generation by myosin cross bridges to increase Ca(2+)-sensitivity of the contractile apparatus. Stimulation-induced increases in RLC phosphorylation in intact muscle produces isometric and concentric force potentiation to enhance dynamic aspects of muscle work and power in unfatigued or fatigued muscle. Moreover, RLC phosphorylation-mediated enhancements may interact with neural strategies for human skeletal muscle activation to ameliorate either central or peripheral aspects of fatigue.
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Affiliation(s)
- James T Stull
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, 75390-9040, USA.
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4
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Haydon CE, Watt PW, Morrice N, Knebel A, Gaestel M, Cohen P. Identification of a phosphorylation site on skeletal muscle myosin light chain kinase that becomes phosphorylated during muscle contraction. Arch Biochem Biophys 2002; 397:224-31. [PMID: 11795875 DOI: 10.1006/abbi.2001.2625] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A protein phosphorylated efficiently in vitro by MAP kinase-activated protein kinase-2 (MAPKAP-K2) was purified from skeletal muscle extracts and identified as the calcium/calmodulin-dependent myosin light chain kinase (MLCK). The phosphorylation site was mapped to Ser(161), a residue shown previously to be autophosphorylated by MLCK. The residue equivalent to Ser(161) became phosphorylated in vivo when rat hindlimbs were stimulated electrically. However, phosphorylation was triggered within seconds, whereas activation of MAPKAP-K2 required several minutes. Moreover, contraction-induced Ser(161) phosphorylation was similar in wild-type or MAPKAP-K2-/- mice. These results indicate that contraction-induced phosphorylation is probably catalyzed by MLCK and not MAPKAP-K2. Ser(161) phosphorylation induced the binding of MLCK to 14-3-3 proteins, but did not detectably affect the kinetic properties of MLCK. The sequence surrounding Ser(161) is unusual in that residue 158 is histidine. Previously, an arginine located three residues N-terminal to the site of phosphorylation was thought to be critical for the specificity of MAPKAP-K2.
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Affiliation(s)
- Claire E Haydon
- MRC Protein Phosphorylation Unit, University of Dundee, Dundee, DD1 5EH, Scotland, UK
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5
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Price NE, Mumby MC. Effects of regulatory subunits on the kinetics of protein phosphatase 2A. Biochemistry 2000; 39:11312-8. [PMID: 10985776 DOI: 10.1021/bi0008478] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Both the scaffold (A) and the regulatory (R) subunits of protein phosphatase 2A regulate enzyme activity and specificity. Heterotrimeric enzymes containing different R-subunits differ in their specific activities for substrates. Kinetic parameters for the dephosphorylation of a phosphopeptide by different oligomeric forms of PP2A were determined to begin to elucidate the molecular basis of regulatory subunit effects on phosphatase activity. Using steady state kinetics and the pH dependence of kinetic parameters, we have explored the effect of the A- and R-subunits on the kinetic and chemical mechanism of PP2A. The regulatory subunits affected a broad range of kinetic parameters. The C-subunit and AC dimer were qualitatively similar with respect to the product inhibition patterns and the pH dependence of kinetic parameters. However, a 22-fold decrease in rate and a 4.7-fold decrease in K(m) can be attributed to the presence of the A-subunit. The presence of the R2alpha (Balpha or PR55alpha) subunit caused an additional decrease in K(m) and changed the kinetic mechanism of peptide dephosphorylation. The R2alpha-subunit also caused significant changes in the pH dependence of kinetic parameters as compared to the free C subunit or AC heterodimer. The data support an important role for the regulatory subunits in determining both the affinity of PP2A heterotrimers for peptide substrates and the mechanism by which they are dephosphorylated.
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Affiliation(s)
- N E Price
- Department of Pharmacology, University of Texas Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, Texas 75390-9041, USA
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6
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Yoshida H, Nozu F, Lankisch TO, Mitamura K, Owyang C, Tsunoda Y. A possible role for Ca(2+)/calmodulin-dependent protein kinase IV during pancreatic acinar stimulus-secretion coupling. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1497:155-67. [PMID: 10838169 DOI: 10.1016/s0167-4889(00)00051-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Ca(2+)/calmodulin-dependent protein kinases (CaMKs) are important intracellular mediators in the mediation of stimulus-secretion coupling and excitation-contraction coupling in a wide variety of cell types. We attempted to identify and characterize the functional roles of CaMK in mediating pancreatic enzyme secretion. Immunoprecipitation and immunoblotting studies using a CaMKII or CaMKIV antibody showed that rat pancreatic acini expressed both CaMKII and CaMKIV. Phosphotransferase activities of CaMKs were measured by a radioenzyme assay (REA) using autocamtide II, peptide gamma and myosin P-light chain as substrates. Although CaMKII and CaMKIV use autocamtide II as a substrate, peptide gamma is more efficiently phosphorylated by CaMKIV than by CaMKII. Intact acini were stimulated with cholecystokinin (CCK)-8, carbachol (CCh) and the high-affinity CCK-A receptor agonist, CCK-OPE, and the cell lysates were used for REA. CCK-8, CCh and CCK-OPE caused a concentration-dependent increase in CaMKs activities. When autocamtide II was used, maximal increases were 1.5-1.8-fold over basal (20.2+/-2.0 pmol/min/mg protein), with peaks occurring at 20 min after cell stimulation. In separate studies that used peptide gamma, CCK-8, CCh and CCK-OPE dose-dependently increased CaMKIV activities. Maximal increases were 1.5-2.4-fold over basal (30.7+/-3. 2 pmol/min/mg protein) with peaks occurring at 20 min after cell stimulation. Peak increases after cell stimulation induced by peptide gamma were 1.8-2.8-fold higher than those induced by autocamtide II. CCK-8, CCh and CCK-OPE also significantly increased phosphotransferase activities of myosin light chain kinase (MLCK) substrate (basal: 4.4+/-0.7 pmol/min/mg protein). However, maximal increases induced by MLCK substrate were less than 10% of those occurring in peptide gamma. Characteristics of the phosphotransferase activity were also different between autocamtide II and peptide gamma. When autocamtide II was used, elimination of medium Ca(2+) in either cell lysates or intact cells resulted in a significant decrease in the activity, whereas it had no or little effect when peptide gamma was used. This suggests that Ca(2+) influx from the extracellular space is not fully required for CaMKIV activity and Ca(2+) is not a prerequisite for phosphotransferase activity once CaMKIV is activated by either intracellular Ca(2+) release or intracellular Ca(2+) oscillations. The specific CaMKII inhibitor KN-62 (50 microM) had no effect on the CaMKIV activity and pancreatic enzyme secretion elicited by CCK-8, CCh and CCK-OPE. The specific MLCK inhibitor, ML-9 (10 microM), also did not inhibit CCK-8-stimulated pancreatic amylase secretion. In contrast, wide spectrum CaMK inhibitors, K-252a (1 microM) and KT5926 (3 microM), significantly inhibited CaMKIV activities and enzyme secretion evoked by secretagogues. Thus, CaMKIV appears to be an important intracellular mediator during stimulus-secretion coupling of rat pancreatic acinar cells.
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Affiliation(s)
- H Yoshida
- Department of Internal Medicine, MSRB I, #6510B, Box 0682, University of Michigan, Ann Arbor, MI 48109, USA
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7
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Hook SS, Kemp BE, Means AR. Peptide specificity determinants at P-7 and P-6 enhance the catalytic efficiency of Ca2+/calmodulin-dependent protein kinase I in the absence of activation loop phosphorylation. J Biol Chem 1999; 274:20215-22. [PMID: 10400638 DOI: 10.1074/jbc.274.29.20215] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Phosphorylation of Ca2+/calmodulin-dependent protein kinase I (CaM KI) at Thr-177 by recombinant rat Ca2+/calmodulin-dependent kinase kinase B (CaM KKB) modulates the kinetics of synapsin-(4-13) peptide phosphorylation by reducing the Km 44-fold and decreasing the KCaM 4-fold. There is also a slight decrease in Km for ATP and increase in enzyme Vmax. A synthetic peptide substrate from the yeast transcription factor, ADR1-(222-234)G233 is a 15-fold better substrate for the Thr-177 dephospho-form of CaM KI than synapsin-(4-13). The Thr-177 dephospho-enzyme has a Km and Vmax for ADR1-(222-234)G233 similar to the values with synapsin-(4-13) using the Thr-177 phosphorylated enzyme. Likewise, with ADR1-(222-234)G233 as substrate, phosphorylation of Thr-177 or substitution of T177A had very little effect on the kinetic values. Using chimeric peptides between synapsin-(4-13) and ADR1-(222-234)G233 we found that N-terminal basic residues at P-7 and P-6 positions were sufficient to allow efficient phosphorylation by the Thr-177 dephospho-form of CaM KI. Phosphorylation of Thr-177 expands the substrate specificity of CaM KI and is not merely an "on-off" switch for kinase activity.
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Affiliation(s)
- S S Hook
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina 27710, USA
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8
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Xu Y, He J, Tian HL, Chan CH, Liao J, Yan T, Lam TJ, Gong Z. Fast skeletal muscle-specific expression of a zebrafish myosin light chain 2 gene and characterization of its promoter by direct injection into skeletal muscle. DNA Cell Biol 1999; 18:85-95. [PMID: 10025512 DOI: 10.1089/104454999315655] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A zebrafish myosin light chain 2 cDNA clone was isolated and characterized. Sequence analysis of the clone revealed a high homology with the mammalian and avian genes encoding the fast skeletal muscle isoform, MLC2f. In situ hybridization and Northern blot hybridization analyses indicated that the zebrafish MLC2f mRNA is expressed exclusively in the fast skeletal muscle. Ontogenetically, the MLC2f mRNA appears around 16 hours postfertilization (hpf) in the first few well-formed anterior somites. At later stages, the MLC2f mRNA can also be detected in fin buds, eye muscles, and jaw muscles. To develop a useful model system for analyzing muscle gene regulation, the promoter of the zebrafish MLC2f gene was isolated and linked to the chloramphenicol acetyltransferase (CAT) reporter gene. The MLC2f/CAT chimeric constructs were analyzed by direct injection into the zebrafish skeletal muscle, and significant CAT activity was observed; in contrast, little or no CAT activity was generated from a similarly injected prolactin gene promoter/CAT gene construct. Within the 1 kb of the MLC2f promoter region, several MEF2-binding sites and E-boxes were identified, suggesting that MLC2f can be regulated by muscle transcription factors MEF2 and myogenic bHLH proteins. A 5' deletion analysis indicated that the proximal 79 nucleotides from the transcription start site, which contains a single MEF2-binding site, is sufficient to drive a high level of CAT activity in injected muscle. Internal deletion of the MEF2 element in the -79-bp construct caused an 80% decrease in CAT activity, whereas internal deletion of the same MEF2 element in a -1044-bp construct had no effect on induced CAT activity. These observations suggest that an MEF2 element is important to activate the MLC2f gene in muscle cells, and the effect of loss of the proximal MEF2 element can be compensated for by the presence of the upstream MEF2 elements. This study also demonstrated that direct injection of DNA into skeletal muscle is a valid and valuable approach to analyze muscle gene promoters in the zebrafish.
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Affiliation(s)
- Y Xu
- Department of Biological Sciences, National University of Singapore, Singapore
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9
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Krueger JK, Zhi G, Stull JT, Trewhella J. Neutron-scattering studies reveal further details of the Ca2+/calmodulin-dependent activation mechanism of myosin light chain kinase. Biochemistry 1998; 37:13997-4004. [PMID: 9760234 DOI: 10.1021/bi981311d] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Previously, we utilized small-angle X-ray scattering and neutron scattering with contrast variation to obtain the first low-resolution structure of 4Ca2+.calmodulin (CaM) complexed with a functional enzyme, an enzymatically active truncation mutant of skeletal muscle myosin light chain kinase (MLCK). These experiments showed that, upon binding to MLCK, CaM undergoes a conformational collapse identical to that observed when CaM binds to the isolated peptide corresponding to the CaM binding sequence of MLCK. CaM thereby was shown to release the inhibition of the kinase by inducing a significant movement of its CaM binding and autoinhibitory sequences away from the surface of the catalytic core [Krueger, J. K., Olah, G. A., Rokop, S. E., Zhi, G., Stull, J. T., and Trewhella, J. (1997) Biochemistry 36, 6017-6023]. We report here similar scattering experiments on the CaM.MLCK complex with the addition of substrates; a nonhydrolyzable analogue of adenosine-triphosphate, AMPPNP, and a peptide substrate for MLCK, a phosphorylation sequence from myosin regulatory light chain (pRLC). These substrates are shown to induce an overall compaction of the complex. The separation of the centers-of-mass of the CaM and MLCK components is shortened (by approximately 12 A), thus bringing CaM closer to the catalytic site compared to the complex without substrates. In addition, there appears to be a reorientation of CaM with respect to the kinase upon substrate binding that results in interactions between the N-terminal sequence of CaM and the kinase that were not observed in the complex without substrates. Finally, the kinase itself becomes more compact in the CaM.MLCK.pRLC.AMPPNP complex compared to the complex without substrates. This observed compaction of MLCK upon substrate binding is similar to that arising from the closure of the catalytic cleft in cAMP-dependent protein kinase upon binding pseudosubstrate.
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Affiliation(s)
- J K Krueger
- Chemical Science and Technology Division, Los Alamos National Laboratory, New Mexico 87545, USA
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10
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Heierhorst J, Tang X, Lei J, Probst WC, Weiss KR, Kemp BE, Benian GM. Substrate specificity and inhibitor sensitivity of Ca2+/S100-dependent twitchin kinases. EUROPEAN JOURNAL OF BIOCHEMISTRY 1996; 242:454-9. [PMID: 9022668 DOI: 10.1111/j.1432-1033.1996.454rr.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Myosin-associated giant protein kinases of the titin/witchin-like superfamily have previously been implicated in the regulation of muscle function, based on genetic and physiological studies. We find that recombinant constitutively active Caenorhabditis elegans and Aplysia twitchin kinase fragments differ in their catalytic activities and peptide-substrate specificities, as well as in their sensitivities to the naphthalene sulfonamide inhibitors 1-(5-chloronaphthalenesulfonyl)-1H-hexahydro-1,4-diazepine (ML-7) and 1-(5-iodonaphthalenesulfonyl)-1H-hexahydro-1,4-diazepine (ML-9). The constitutively active Aplysia twitchin kinase fragment has a remarkably high activity (Vmax > 100 mumol.min-1.mg-1) towards some substrate peptides. The autoinhibited forms of these twitchin kinases can be activated in a Ca(2+)-dependent manner by the dimeric form of the S100A1 protein (S100A1(2)). The twitchin kinase S100A1(2)-binding site can also bind Ca2+/calmodulin but neither kinase is activated by calmodulin. The data provide a functional basis for the ongoing crystallographic study of twitchin kinase fragments.
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Affiliation(s)
- J Heierhorst
- St Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
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11
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Gao ZH, Zhi G, Herring BP, Moomaw C, Deogny L, Slaughter CA, Stull JT. Photoaffinity labeling of a peptide substrate to myosin light chain kinase. J Biol Chem 1995; 270:10125-35. [PMID: 7730316 DOI: 10.1074/jbc.270.17.10125] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
The substrate binding properties of skeletal muscle myosin light chain kinase were investigated with a synthetic peptide containing the photoreactive amino acid p-benzoylphenylalanine (Bpa) incorporated amino-terminal of the phosphoacceptor serine (BpaKKRAARATSNVFA). When photolyzed at 350 nm, the peptide was cross-linked stoichiometrically to myosin light chain kinase in a Ca2+/calmodulin-dependent manner. Peptide incorporation into kinase inhibited light chain phosphorylation, and the loss of kinase activity was proportional to the extent of peptide incorporated. After peptide I was incorporated into myosin light chain kinase, it was partially phosphorylated in the absence of Ca2+/calmodulin. The extent of phosphorylation increased in the presence of Ca2+/calmodulin. The cross-linked photoadduct was digested, labeled peptides were purified by high performance liquid chromatography, and sites of covalent modification were determined by amino acid sequencing and analysis. The covalent modification in the catalytic core occurred on Ile-373 (66%) and in a peptide containing residues Asn-422 to Met-437 (14%), respectively. Lys-572 in the autoinhibitory region accounted for 20% of the incorporated label. The coincident covalent modification of the autoinhibitory domain suggests that it is located near the catalytic site. Based upon a model of the catalytic core, the substrate peptide is predicted to bind in the cleft between the two lobes of the kinase. The orientation of the substrate peptide on myosin light chain kinase is similar to the orientation of the substrate recognition fragment, but not the high affinity binding fragment, of inhibitor peptide of cAMP-dependent protein kinase in the catalytic subunit of the cAMP-dependent protein kinase.
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Affiliation(s)
- Z H Gao
- Department of Physiology, University of Texas Southwestern Medical Center at Dallas 75235, USA
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12
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Structural requirement of the regulatory light chain of smooth muscle myosin as a substrate for myosin light chain kinase. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(18)46909-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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13
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Zhi G, Herring B, Stull J. Structural requirements for phosphorylation of myosin regulatory light chain from smooth muscle. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)31451-5] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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14
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Abukhalaf IK, Masaracchia RA. Protein phosphatase assay using a modification of the P81 paper protein kinase assay procedure. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 1993; 26:95-104. [PMID: 8389782 DOI: 10.1016/0165-022x(93)90039-q] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
Synthetic peptides have been used to define specificity determinants and to distinguish reactivities of numerous protein kinases and phosphoprotein phosphatases. Direct analysis of peptide phosphorylation is most often determined using P81 phosphocellulose paper to separate modified peptide and unreacted [gamma-32P]ATP; however phosphopeptide dephosphorylation is usually determined by extraction and quantitation of phosphomolybdate complexes or ion exchange chromatography. We describe here the adaptation of the rapid, direct P81 paper protein kinase assay for the determination of phosphopeptide dephosphorylation. The S6-21 peptide (AKRRRLSSLRASTSKSESSQK), which is derived from the multiphosphorylated carboxyl terminal domain of the S6 ribosomal protein, was phosphorylated by a human placenta S6 kinase and dephosphorylation by purified phosphoprotein phosphatase type 1 in the presence of a variety of buffers, and inhibitors/activators was determined using the new assay. Results comparable to those obtained with the ion-exchange chromatography were obtained, and the assay was significantly less expensive, more rapid, and more accurate than methods previously used to quantitate phosphopeptide dephosphorylation.
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Affiliation(s)
- I K Abukhalaf
- Division of Biochemistry, University of North Texas, Denton 76203
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15
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16
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Knighton DR, Pearson RB, Sowadski JM, Means AR, Ten Eyck LF, Taylor SS, Kemp BE. Structural basis of the intrasteric regulation of myosin light chain kinases. Science 1992; 258:130-5. [PMID: 1439761 DOI: 10.1126/science.1439761] [Citation(s) in RCA: 105] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The smooth muscle myosin light chain kinase (smMLCK) catalytic core was modeled by using the crystallographic coordinates of the cyclic AMP-dependent protein kinase catalytic subunit (cAPK) and a bound pseudosubstrate inhibitor peptide, PKI(5-24). Despite only 30% identity in amino acid sequence, the MLCK sequence can be readily accommodated in this structure. With the exception of the short B-helix, all major elements of secondary structure in the core are very likely conserved. The active site of the modeled MLCK complements the known requirements for peptide substrate recognition. MLCK contains a pseudosubstrate sequence that overlaps the calmodulin binding domain and has been proposed to act as an intrasteric inhibitor and occupy the substrate binding site in the absence of Ca(2+)-calmodulin. The pseudosubstrate sequence can be modeled easily into the entire backbone of PKI(5-24). The results demonstrate that the intrasteric model for regulation of MLCK by intramolecular competitive inhibition is structurally plausible.
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Affiliation(s)
- D R Knighton
- Department of Chemistry, University of California San Diego, La Jolla 92093-0654
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17
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Moreland S, Ikebe M, Hunt JT, Moreland RS. Substrate based inhibitors of smooth muscle myosin light chain kinase. Biochem Biophys Res Commun 1992; 185:379-85. [PMID: 1599475 DOI: 10.1016/s0006-291x(05)80996-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Activation of myosin light chain kinase is a prerequisite for smooth muscle activation. In this study, short peptide analogs of the phosphorylation site of the myosin light chain were studied for their effects on several contractile protein systems. The peptides inhibited phosphorylation of isolated ventricular and smooth muscle myosin light chains by smooth muscle myosin light chain kinase, but they were only weak inhibitors of phosphorylation of intact myosin and actomyosin. The peptides were also unable to block force development or myosin light chain phosphorylation in glycerol permeabilized fibers of swine carotid media. Apparently, the association of the myosin light chain with myosin changes its conformation such that substrate analogs which are potent inhibitors of the phosphorylation of isolated myosin light chains by myosin light chain kinase are ineffective at blocking phosphorylation of the intact molecule.
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Affiliation(s)
- S Moreland
- Department of Pharmacology, Bristol-Myers Squibb Pharmaceutical Research Institute, Princeton, NJ 08543
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18
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Bowman B, Peterson J, Stull J. Pre-steady-state kinetics of the activation of rabbit skeletal muscle myosin light chain kinase by Ca2+/calmodulin. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42772-x] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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19
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Leachman S, Gallagher P, Herring B, McPhaul M, Stull J. Biochemical properties of chimeric skeletal and smooth muscle myosin light chain kinases. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42920-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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20
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Nakabayashi H, Sellers JR, Huang KP. Catalytic fragment of protein kinase C exhibits altered substrate specificity toward smooth muscle myosin light chain. FEBS Lett 1991; 294:144-8. [PMID: 1743284 DOI: 10.1016/0014-5793(91)81362-c] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Smooth muscle myosin light chain (LC) can be phosphorylated by myosin light chain kinase (MLCK) at Ser19 and Thr18 and by protein kinase C (PKC) at Thr9 and Ser1 or Ser2 under the in vitro assay conditions. Conversion of PKC to the spontaneously active protein kinase M (PKM) by proteolysis resulted in a change in the substrate specificity of the kinase. PKM phosphorylated both sets of sites in LC recognized by MLCK and PKC as analyzed by peptide mapping analysis. The PKM-catalyzed phosphorylation of these sites was not greatly affected by a MLCK inhibitor, ML-9, nor by the activators of MLCK, Ca2+ and calmodulin.
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Affiliation(s)
- H Nakabayashi
- Endocrinology and Reproduction Research Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, Maryland 20892
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21
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Kennelly P, Krebs E. Consensus sequences as substrate specificity determinants for protein kinases and protein phosphatases. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98436-x] [Citation(s) in RCA: 991] [Impact Index Per Article: 30.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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22
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Kamibayashi C, Estes R, Slaughter C, Mumby M. Subunit interactions control protein phosphatase 2A. Effects of limited proteolysis, N-ethylmaleimide, and heparin on the interaction of the B subunit. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)98831-9] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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23
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Basic residues are important for Ca2+/calmodulin binding and activation but not autoinhibition of rabbit skeletal muscle myosin light chain kinase. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99033-2] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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24
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Collins JH. Myosin light chains and troponin C: structural and evolutionary relationships revealed by amino acid sequence comparisons. J Muscle Res Cell Motil 1991; 12:3-25. [PMID: 2050809 DOI: 10.1007/bf01781170] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- J H Collins
- Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore 21201
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25
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26
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Pearson RB, Kemp BE. Protein kinase phosphorylation site sequences and consensus specificity motifs: tabulations. Methods Enzymol 1991; 200:62-81. [PMID: 1956339 DOI: 10.1016/0076-6879(91)00127-i] [Citation(s) in RCA: 843] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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27
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Herring BP, Fitzsimons DP, Stull JT, Gallagher PJ. Acidic residues comprise part of the myosin light chain-binding site on skeletal muscle myosin light chain kinase. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)46263-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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28
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Brzeska H, Lynch TJ, Martin B, Corigliano-Murphy A, Korn ED. Substrate specificity of Acanthamoeba myosin I heavy chain kinase as determined with synthetic peptides. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)46199-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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29
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Buechler JA, Taylor SS. Differential labeling of the catalytic subunit of cAMP-dependent protein kinase with a water-soluble carbodiimide: identification of carboxyl groups protected by MgATP and inhibitor peptides. Biochemistry 1990; 29:1937-43. [PMID: 2331473 DOI: 10.1021/bi00459a039] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The catalytic subunit of cAMP-dependent protein kinase typically phosphorylates protein substrates containing basic amino acids preceding the phosphorylation site. To identify amino acids in the catalytic subunit that might interact with these basic residues in the protein substrate, the enzyme was treated with a water-soluble carbodiimide, 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC), in the presence of [14C]glycine ethyl ester. Modification of the catalytic subunit in the absence of substrates led to the irreversible, first-order inhibition of activity. Neither MgATP nor a 6-residue inhibitor peptide alone was sufficient to protect the catalytic subunit against inactivation by the carbodiimide. However, the inhibitor peptide and MgATP together completely blocked the inhibitory effects of EDC. Several carboxyl groups in the free catalytic subunit were radiolabeled after the catalytic subunit was modified with EDC and [14C]glycine ethyl ester. After purification and sequencing, these carboxyl groups were identified as Glu 107, Glu 170, Asp 241, Asp 328, Asp 329, Glu 331, Glu 332, and Glu 333. Three of these amino acids, Glu 331, Glu 107, and Asp 241, were labeled regardless of the presence of substrates, while Glu 333 and Asp 329 were modified to a slight extent only in the free catalytic subunit. Glu 170, Asp 328, and Glu 332 were all very reactive in the apoenzyme but fully protected from modification by EDC in the presence of MgATP and an inhibitor peptide.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- J A Buechler
- Department of Chemistry, University of California, San Diego, La Jolla 92093
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30
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Singer HA, Oren JW, Benscoter HA. Myosin light chain phosphorylation in 32P-labeled rabbit aorta stimulated by phorbol 12,13-dibutyrate and phenylephrine. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)30069-9] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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31
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32
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Kennelly PJ, Starovasnik M, Krebs EG. Activation of rabbit skeletal muscle myosin light chain kinase by calmodulin--a mechanistic overview. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1989; 255:155-64. [PMID: 2618854 DOI: 10.1007/978-1-4684-5679-0_17] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- P J Kennelly
- Howard Hughes Medical Institute, University of Washington, Seattle 98195
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33
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Kemp BE, Pearson RB, House C, Robinson PJ, Means AR. Regulation of protein kinases by pseudosubstrate prototopes. Cell Signal 1989; 1:303-11. [PMID: 2561987 DOI: 10.1016/0898-6568(89)90049-1] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- B E Kemp
- St. Vincent's Institute of Medical Research, Fitzroy Vic. Australia
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34
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35
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Kennelly PJ, Edelman AM, Blumenthal DK, Krebs EG. Rabbit skeletal muscle myosin light chain kinase. The calmodulin binding domain as a potential active site-directed inhibitory domain. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45302-1] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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36
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Substrate specificity determinants for casein kinase II as deduced from studies with synthetic peptides. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)48058-1] [Citation(s) in RCA: 304] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
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37
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Structural studies of rabbit skeletal muscle myosin light chain kinase with monoclonal antibodies. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61431-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
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