Allostery is a fundamental mechanism of protein activation, yet the precise dynamic changes that underlie functional regulation of allosteric enzymes, such as glycogen phosphorylase (GlyP), remain poorly understood. Despite being the first allosteric enzyme described, its structural regulation is still a challenging problem: the key regulatory loops of the GlyP active site (250' and 280s) are weakly stable and often missing density or have large b-factors in structural models. This led to the longstanding hypothesis that GlyP regulation is achieved through gating of the active site by (dis)order transitions, as first proposed by Barford and Johnson. However, testing this requires a quantitative measurement of weakly stable local structure which, to date, has been technically challenging in such a large protein. Hydrogen-deuterium-exchange mass spectrometry (HDX-MS) is a powerful tool for studying protein dynamics, and millisecond HDX-MS has the ability to measure site-localized stability differences in weakly stable structures, making it particularly valuable for investigating allosteric regulation in GlyP. Here, we used millisecond HDX-MS to measure the local structural perturbations of glycogen phosphorylase b (GlyPb), the phosphorylated active form (GlyPa), and the inhibited glucose-6 phosphate complex (GlyPb:G6P) at near-amino acid resolution. Our results support the Barford and Johnson hypothesis for GlyP regulation by providing insight into the dynamic changes of the key regulatory loops.
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http://dx.doi.org/10.1021/acs.biochem.2c00671 | DOI Listing |
Sci Rep
December 2024
University of Jammu, Jammu and Kashmir, 180006, India.
Nesfatin-1 is a crucial regulator of energy homeostasis in mammals and fishes, however, its metabolic role remains completely unexplored in amphibians, reptiles, and birds. Therefore, present study elucidates role of nesfatin-1 in glucose homeostasis in wall lizard wherein fasting stimulated hepatic nucb2/nesfatin-1, glycogen phosphorylase (glyp), phosphoenolpyruvate carboxykinase (pepck), and fructose 1,6-bisphosphatase (fbp), while feeding upregulated pancreatic nucb2/nesfatin-1 and insulin, suggesting towards tissue-specific dual role of nesfatin-1 in glucoregulation. The glycogenolytic/gluconeogenic role of nesfatin-1 was further confirmed by an increase in media glucose levels along with heightened hepatic pepck and fbp expression and concomitant decline in liver glycogen content in nesfatin-1-treated liver of wall lizard.
View Article and Find Full Text PDFAnal Sci
December 2024
School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura, Hachioji, Tokyo, 192-0982, Japan.
A biosensor for biochemical oxygen demand (BOD) was developed based on intracellular 5'-adenosine triphosphate (ATP) measurements in Saccharomyces cerevisiae. Intracellular ATP was measured using an engineered protein named ATeam, comprising a bacterial FF-ATP synthase ε subunit sandwiched between cyan fluorescent protein and mVenus, a modified yellow fluorescent protein. Because the binding of ATP to ATeam induces changes in the fluorescence spectra owing to Fӧrster resonance energy transfer, S.
View Article and Find Full Text PDFOrphanet J Rare Dis
December 2024
Assistant Professor of Cellular and Molecular Medicine, Shiraz Transplant Research Center, Shiraz University of Medical Sciences, Khalili St., Research Tower, Seventh Floor, Shiraz, Iran.
Glycogen storage disorders (GSD) GSD-IX are characterized by deficiencies in muscular and/or hepatic phosphorylase enzymes. GSD type IX za is an X-linked disorder, while IXb and IXc are autosomal recessive disorders resulting from pathogenic variants in the genes encoding the Phosphorylase b Kinase regulatory subunit alpha (PHKA), beta (PHKB), and gamma (PHKG), respectively. Despite progress in understanding these diseases, there are still unclear questions regarding their clinical manifestations, genetic variations, and the relationship between genotype and phenotype.
View Article and Find Full Text PDFFront Nutr
November 2024
Centre for Quality of Health and Living, Faculty of Health and Environmental Sciences, Central University of Technology, Bloemfontein, South Africa.
Background: African walnut () oil (AWO) has been reported for its nutritional and medicinal properties and has been employed for the management of metabolic diseases including hyperglycemia-mediated ailments.
Objective: In the present study, AWO was investigated for its ability to stimulate glucose uptake and its effect on energy metabolism, steroidogenesis, and tissue morphology in isolated testes of Wistar rats.
Methods: Isolated testes were incubated with AWO (30-240 μg/mL) in the presence of 11.
Antioxidants (Basel)
November 2024
Aging Stress Response Research Project Team, National Center for Geriatrics and Gerontology, Aichi 474-8511, Japan.
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