1
|
Kamada N, Ikeda A, Makino Y, Matsubara H. Intersubunit communication in glycogen phosphorylase influences substrate recognition at the catalytic sites. Amino Acids 2024; 56:14. [PMID: 38340233 PMCID: PMC10858836 DOI: 10.1007/s00726-023-03362-6] [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] [Received: 12/15/2022] [Accepted: 12/18/2023] [Indexed: 02/12/2024]
Abstract
Glycogen phosphorylase (GP) is biologically active as a dimer of identical subunits, each activated by phosphorylation of the serine-14 residue. GP exists in three interconvertible forms, namely GPa (di-phosphorylated form), GPab (mono-phosphorylated form), and GPb (non-phosphorylated form); however, information on GPab remains scarce. Given the prevailing view that the two GP subunits collaboratively determine their catalytic characteristics, it is essential to conduct GPab characterization to gain a comprehensive understanding of glycogenolysis regulation. Thus, in the present study, we prepared rabbit muscle GPab from GPb, using phosphorylase kinase as the catalyst, and identified it using a nonradioactive phosphate-affinity gel electrophoresis method. Compared with the half-half GPa/GPb mixture, the as-prepared GPab showed a unique AMP-binding affinity. To further investigate the intersubunit communication in GP, its catalytic site was probed using pyridylaminated-maltohexaose (a maltooligosaccharide-based substrate comprising the essential dextrin structure for GP; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (substrate analogs lacking part of the essential dextrin structure). By comparing the initial reaction rates toward the PA-0 derivative (Vderivative) and PA-0 (VPA-0), we demonstrated that the Vderivative/VPA-0 ratio for GPab was significantly different from that for the half-half GPa/GPb mixture. This result indicates that the interaction between the two GP subunits significantly influences substrate recognition at the catalytic sites, thereby providing GPab its unique substrate recognition profile.
Collapse
Affiliation(s)
- Nahori Kamada
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Ayato Ikeda
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
| | - Yasushi Makino
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Japan.
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan.
| | - Hiroshi Matsubara
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Sakai, Japan
- Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan
| |
Collapse
|
2
|
Nakamura M, Makino Y, Takagi C, Yamagaki T, Sato M. Probing the catalytic site of rabbit muscle glycogen phosphorylase using a series of specifically modified maltohexaose derivatives. Glycoconj J 2017; 34:563-574. [PMID: 28597243 DOI: 10.1007/s10719-017-9776-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2017] [Revised: 05/12/2017] [Accepted: 05/15/2017] [Indexed: 02/05/2023]
Abstract
Glycogen phosphorylase (GP) is an allosteric enzyme whose catalytic site comprises six subsites (SG1, SG-1, SG-2, SG-3, SG-4, and SP) that are complementary to tandem five glucose residues and one inorganic phosphate molecule, respectively. In the catalysis of GP, the nonreducing-end glucose (Glc) of the maltooligosaccharide substrate binds to SG1 and is then phosphorolyzed to yield glucose 1-phosphate. In this study, we probed the catalytic site of rabbit muscle GP using pyridylaminated-maltohexaose (Glcα1-4Glcα1-4Glcα1-4Glcα1-4Glcα1-4GlcPA, where GlcPA = 1-deoxy-1-[(2-pyridyl)amino]-D-glucitol]; abbreviated as PA-0) and a series of specifically modified PA-0 derivatives (Glc m -AltNAc-Glc n -GlcPA, where m + n = 4 and AltNAc is 3-acetoamido-3-deoxy-D-altrose). PA-0 served as an efficient substrate for GP, whereas the other PA-0 derivatives were not as good as the PA-0, indicating that substrate recognition by all the SG1 -SG-4 subsites was important for the catalysis of GP. By comparing the initial reaction rate toward the PA-0 derivatives (V derivative) with that toward PA-0 (V PA-0), we found that the value of V derivative/V PA-0 decreased significantly as the level of allosteric activation of GP increased. These results suggest that some conformational changes have taken place in the maltooligosaccharide-binding region of the GP catalytic site during allosteric regulation.
Collapse
Affiliation(s)
- Makoto Nakamura
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan
| | - Yasushi Makino
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan.
| | - Chika Takagi
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan
| | - Tohru Yamagaki
- Bioorganic Research Institute, Suntory Foundation for Life Sciences, Seika-cho, Soraku-gun, Kyoto, 619-0284, Japan
| | - Masaaki Sato
- Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Gakuen-cho 1-1, Naka-ku, Sakai, Osaka, 599-8531, Japan
| |
Collapse
|
3
|
Abstract
The fat body plays major roles in the life of insects. It is a dynamic tissue involved in multiple metabolic functions. One of these functions is to store and release energy in response to the energy demands of the insect. Insects store energy reserves in the form of glycogen and triglycerides in the adipocytes, the main fat body cell. Insect adipocytes can store a great amount of lipid reserves as cytoplasmic lipid droplets. Lipid metabolism is essential for growth and reproduction and provides energy needed during extended nonfeeding periods. This review focuses on energy storage and release and summarizes current understanding of the mechanisms underlying these processes in insects.
Collapse
|
4
|
Meyer-Fernandes JR, Arrese EL, Wells MA. Allosteric effectors and trehalose protect larval Manduca sexta fat body glycogen phosphorylase B against thermal denaturation. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2000; 30:473-478. [PMID: 10802238 DOI: 10.1016/s0965-1748(00)00016-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
In this paper we assessed the ability of modulators of the activity of glycogen phosphorylase b from the fat body of larval Manduca sexta to stabilize the enzyme against thermal denaturation. This approach has allowed us to distinguish between modulators that stabilize the enzyme, presumably through some conformational effect, from those that do not affect thermal stability. For example, 5'-AMP and 5'-IMP are both positive modulators of the enzyme and the K(m)s for AMP and IMP were similar, 0.71 and 1.09 mM, respectively. However, the V(max) for AMP (123 nmol/mg/min) was 10 times higher than the value found for IMP (12.5 nmol/mg/min) and AMP increased the thermal stability of glycogen phosphorylase b, however IMP did not increase the enzyme's thermal stability. Indeed, IMP decreased both the allosteric activation of the enzyme by AMP and the thermal protection conferred by AMP. The allosteric inhibitors ADP and ATP, which in vertebrate phosphorylase bind to the same site as AMP, both increased the thermal stability of the enzyme, however with less efficiency than AMP. Inorganic phosphate increased thermal stability, but glycogen and amylose did not. Glycerol, at 600 mM, protected the enzyme against thermal inactivation, whereas sorbitol at the same concentration did not show any effect. Among the polyols tested, trehalose was the most effective in conferring thermal stability. In fact, in the presence of 20 mM AMP and 600 mM trehalose, 90% of the enzyme activity remained after 20 min at 60 degrees C.
Collapse
Affiliation(s)
- J R Meyer-Fernandes
- Department of Biochemistry and Center for Insect Science, Biological Sciences West, University of Arizona, Tucson, USA
| | | | | |
Collapse
|
5
|
Steele JE, Ireland R. Hormonal activation of phosphorylase in cockroach fat body trophocytes: A correlation with trans-membrane calcium flux. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 1999; 42:233-244. [PMID: 10578113 DOI: 10.1002/(sici)1520-6327(199912)42:4<233::aid-arch2>3.0.co;2-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
This study is an investigation of the temporal relationship between transmembrane Ca(2+) fluxes, and glycogen phosphorylase activation in dispersed trophocytes from the fat body of the cockroach, Periplaneta americana. Phosphorylase is maximally activated within 5 min after treating the trophocytes with either of the hypertrehalosemic hormones, Pea-HTH-I and Pea-HTH-II. Activation caused by Pea-HTH-II is sustained for a longer period than that produced by Pea-HTH-I. Chelation of extracellular Ca(2+) with EGTA blocks the activation of phosphorylase by HTH. Similarly, chelation of intracellular Ca(2+) with Quin 2 greatly diminishes the phosphorylase activating effect of both HTHs. The data support the view that an increase in the intracellular Ca(2+ )concentration is required for the activation of phosphorylase and that extracellular Ca(2+) is an essential, although not necessarily sole, source of Ca(2+) for this purpose. Using (45)Ca(2+) to trace the movement of Ca(2+) following a challenge with either Pea-HTH-I or -II, it was shown that (45)Ca(2+)influx nearly doubled during the first 30 s. At this time, the trophocytes begin to expel Ca(2+) at a rate higher than that of untreated cells and this state persists for approximately 4 min. The Ca(2+) fluxes are consistent with its postulated role in the activation of phosphorylase. Arch.
Collapse
Affiliation(s)
- J E Steele
- Department of Zoology, University of Western Ontario, London, Ontario, Canada.
| | | |
Collapse
|
6
|
|
7
|
Krause U, Wegener G. Control of adenine nucleotide metabolism and glycolysis in vertebrate skeletal muscle during exercise. EXPERIENTIA 1996; 52:396-403. [PMID: 8641374 DOI: 10.1007/bf01919306] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The turnover of adenosine triphosphate (ATP) in vertebrate skeletal muscle can increase more than a hundredfold during high-intensity exercise, while the content of ATP in muscle may remain virtually unchanged. This requires that the rates of ATP hydrolysis and ATP synthesis are exactly balanced despite large fluctuations in reaction rates. ATP is regenerated initially at the expense of phosphocreatine (PCr) and then mainly through glycolysis from muscle glycogen. The increased ATP turnover in contracting muscle will cause an increase in the contents of adenosine diphosphate (ADP), adenosine monophosphate (AMP) and inorganic phosphate (P(i)), metabolites that are substrates and activators of regulatory enzymes such as glycogen phosphorylase and phosphofructokinase. An intracellular metabolic feedback mechanism is thus activated by muscle contraction. How muscle metabolism is integrated in the intact body under physiological conditions is not fully understood. Common frogs are suitable experimental animals for the study of this problem because they can readily be induced to change from rest to high-intensity exercise, in the form of swimming. The changes in metabolites and effectors in gastrocnemius muscle were followed during exercise, post-exercise recovery and repeated exercise. The results suggest that glycolytic flux in muscle is modulated by signals from outside the muscle and that fructose 2,6-bisphosphate is a key signal in this process.
Collapse
Affiliation(s)
- U Krause
- Institut für Zoologie, Johannes-Gutenberg-Universität, Mainz, Germany
| | | |
Collapse
|
8
|
Abstract
Insect flight is the most energy-demanding exercise known. It requires very effective coupling of adenosine triphosphate (ATP) hydrolysis and regeneration in the working flight muscles. 31P nuclear magnetic resonance (NMR) spectroscopy of locust flight muscle in vivo has shown that flight causes only a small decrease in the content of ATP, whereas the free concentrations of inorganic phosphate (Pi), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) were estimated to increase by about 3-, 5- and 27-fold, respectively. These metabolites are potent activators of glycogen phosphorylase and phosphofructokinase (PFK). Activation of glycolysis by AMP and Pi is reinforced synergistically by fructose 2,6-biphosphate (F2,6P2), a very potent activator of PFK. During prolonged flight locusts gradually change from using carbohydrate to lipids as their main fuel. This requires a decrease in glycolytic flux which is brought about, at least in part, by a marked decrease in the content of F2,6P2 in flight muscle (by 80% within 15 min of flight). The synthesis of F2,6P2 in flight muscle can be stimulated by the nervous system via the biogenic amine octopamine. Octopamine and F2,6P2 seem to be part of a mechanism to control the rate of carbohydrate oxidation in flight muscle and thus function in the metabolic integration of insect flight.
Collapse
Affiliation(s)
- G Wegener
- Institut für Zoologie, Johannes-Gutenberg-Universität, Mainz, Germany
| |
Collapse
|