Structural Basis for Leucine-induced Allosteric Activation of Glutamate Dehydrogenase

Tanaka, Takeo; Kuzuyama, Tomohisa; Nishiyama, Makoto

doi:10.1074/jbc.m111.260265

Cited by 45 publications

(48 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Glutamate then can be oxidatively deaminated by GDH to generate free ammonia and to regenerate α-ketoglutarate. GDH activity is highly controlled by allosteric regulation; mitochondrial GTP (mtGTP) inhibits GDH, whereas L-leucine activates GDH (22,23). mtGTP is an important mitochondrial energy sensor in both hepatocytes and pancreatic islet cells, reflecting the balance between tricarboxylic acid cycle and gluconeogenic fluxes implicated in glucose production, insulin secretion, and glucagon secretion (2,(24)(25)(26).…”

Section: Discussionmentioning

confidence: 99%

Argininosuccinate synthetase regulates hepatic AMPK linking protein catabolism and ureagenesis to hepatic lipid metabolism

Madiraju

Alves

Zhao

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

A key sensor of cellular energy status, AMP-activated protein kinase (AMPK), interacts allosterically with AMP to maintain an active state. When active, AMPK triggers a metabolic switch, decreasing the activity of anabolic pathways and enhancing catabolic processes such as lipid oxidation to restore the energy balance. Unlike oxidative tissues, in which AMP is generated from adenylate kinase during states of high energy demand, the ornithine cycle enzyme argininosuccinate synthetase (ASS) is a principle site of AMP generation in the liver. Here we show that ASS regulates hepatic AMPK, revealing a central role for ureagenesis flux in the regulation of metabolism via AMPK. Treatment of primary rat hepatocytes with amino acids increased gluconeogenesis and ureagenesis and, despite nutrient excess, induced both AMPK and acetyl-CoA carboxylase (ACC) phosphorylation. Antisense oligonucleotide knockdown of hepatic ASS1 expression in vivo decreased liver AMPK activation, phosphorylation of ACC, and plasma β-hydroxybutyrate concentrations. Taken together these studies demonstrate that increased amino acid flux can activate AMPK through increased AMP generated by ASS, thus providing a novel link between protein catabolism, ureagenesis, and hepatic lipid metabolism.argininosuccinate synthetase | AMPK | ureagenesis | amino acids | lipid metabolism M aintaining appropriate nitrogen balance is crucial to the fitness of an organism. The decision to deaminate amino acids to use their carbon skeleton for oxidative and/or synthetic purposes is tightly regulated. Excessive amino acid catabolism not only generates toxic nitrogenous waste but also could jeopardize the ability to generate or maintain protein levels.The liver is unique in its capacity to detoxify nitrogenous waste through the energy-requiring synthesis of urea. Accounting for nearly a third of hepatic metabolism, ureagenesis consumes three ATPs per urea produced and has an overall flux comparable to that of gluconeogenesis (1, 2). Importantly, the ligation of citrulline to aspartate via argininosuccinate synthetase (ASS) hydrolyzes one ATP into AMP per turn of the ornithine cycle, making ASS a predominant hepatocellular contributor of AMP. Hence, a metabolic signal generated through the AMP-generating ornithine cycle could be intrinsic to preserving nitrogen balance.In oxidative tissues such as muscle, AMPK helps balance energy homeostasis by detecting fluctuations in the [AMP]:[ATP] ratio. Phosphorylation of AMPK by upstream kinases such as liver kinase B1 enhance AMPK activity, and AMP binding to an allosteric site stabilizes a conformation that supports phosphorylation and protects AMPK from dephosphorylation (3). The canonical view of AMPK activation is that, following global shifts in energy balance (e.g., excessive energy demand during exercise), adenylate kinase (AK) increases AMP synthesis to salvage ATP from ADP (4). As a consequence, the AMPK-mediated phosphorylation of sterol regulatory element-binding protein 1 (SREBP-1), acetyl-CoA carboxylase 1 (ACC1), a...

show abstract

Section: Discussionmentioning

confidence: 99%

Argininosuccinate synthetase regulates hepatic AMPK linking protein catabolism and ureagenesis to hepatic lipid metabolism

Madiraju

Alves

Zhao

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

show abstract

“…Some very recent structural results on GDH from an extremely thermophilic bacteria, Thermus thermophilus, suggest that this bithionol/GW5074 binding site might be involved in leucine allosteric activation [79]. There are two forms of GDH in T. thermophilus , GdhA and GdhB, that can form various combinations of GdhA/GdhB heterohexamers.…”

Section: Biothionol and Gw5074 Complex Structuresmentioning

confidence: 99%

The structure and allosteric regulation of mammalian glutamate dehydrogenase

Allen

et al. 2012

Archives of Biochemistry and Biophysics

113

View full text Add to dashboard Cite

Glutamate dehydrogenase (GDH) is a homohexameric enzyme that catalyzes the reversible oxidative deamination of L-glutamate to 2-oxoglutarate. Only in the animal kingdom is this enzyme heavily allosterically regulated by a wide array of metabolites. The major activators are ADP and leucine, while the most important inhibitors include GTP, palmitoyl CoA, and ATP. Recently, spontaneous mutations in the GTP inhibitory site that lead to the hyperinsulinism/hyperammonemia (HHS) syndrome have shed light as to why mammalian GDH is so tightly regulated. Patients with HHS exhibit hypersecretion of insulin upon consumption of protein and concomitantly extremely high levels of ammonium in the serum. The atomic structures of four new inhibitors complexed with GDH complexes have identified three different allosteric binding sites. Using a transgenic mouse model expressing the human HHS form of GDH, at least three of these compounds were found to block the dysregulated form of GDH in pancreatic tissue. EGCG from green tea prevented the hyper-response to amino acids in whole animals and improved basal serum glucose levels. The atomic structure of the ECG-GDH complex and mutagenesis studies is directing structure-based drug design using these polyphenols as a base scaffold. In addition, all of these allosteric inhibitors are elucidating the atomic mechanisms of allostery in this complex enzyme.

show abstract

“…However, a recent study suggests an additional role for leucine, which may contribute to mTORC1 activation through stimulation of glutamine metabolism (Duran et al , 2012). Leucine can stimulate GLUD enzymatic activity, with leucine likely playing a role in subunit interface environment through interaction with Arg 151 and Asp 185 in human GLUD2 (Erecinska & Nelson, 1990; Tomita et al , 2011). Thus, leucine increases GLUD activity and enhances glutaminolysis, activating mTORC1 (Duran et al , 2012).…”

Section: Glutamate Dehydrogenasementioning

confidence: 99%

Stress eating and tuning out: Cancer cells re-wire metabolism to counter stress

Stine¹,

Dang²

2013

Critical Reviews in Biochemistry and Molecular Biology

View full text Add to dashboard Cite

Cancer cells reprogram metabolism to maintain rapid proliferation under often stressful conditions. Glycolysis and glutaminolysis are two central pathways that fuel cancer metabolism. Allosteric regulation and metabolite driven post-translational modifications of key metabolic enzymes allow cancer cells glycolysis and glutaminolysis to respond to changes in nutrient availability and the tumor microenvironment. While increased aerobic glycolysis (the Warburg effect) has been a noted part of cancer metabolism for over 80 years, recent work has shown that the elevated levels of glycolytic intermediates are critical to cancer growth and metabolism due to their ability to feed into the anabolic pathways branching off glycolysis such as the pentose phosphate pathway and serine biosynthesis pathway. The key glycolytic enzymes phosphofructokinase-1 (PFK1), pyruvate kinase (PKM2) and phosphoglycerate mutase 1 (PGAM1) are regulated by upstream and downstream metabolites to balance glycolytic flux with flux through anabolic pathways. Glutamine regulation is tightly controlled by metabolic intermediates that allosterically inhibit and activate glutamate dehydrogenase, which fuels the tricarboxylic acid cycle by converting glutamine derived glutamate to α-ketoglutarate. The elucidation of these key allosteric regulatory hubs in cancer metabolism will be essential for understanding and predicting how cancer cells will respond to drugs that target metabolism. Additionally, identification of the structures involved in allosteric regulation will inform the design of anti-metabolism drugs which bypass the off-target effects of substrate mimics. Hence, this review aims to provide an overview of allosteric control of glycolysis and glutaminolysis.

show abstract

Structural Basis for Leucine-induced Allosteric Activation of Glutamate Dehydrogenase

Cited by 45 publications

References 31 publications

Argininosuccinate synthetase regulates hepatic AMPK linking protein catabolism and ureagenesis to hepatic lipid metabolism

Argininosuccinate synthetase regulates hepatic AMPK linking protein catabolism and ureagenesis to hepatic lipid metabolism

The structure and allosteric regulation of mammalian glutamate dehydrogenase

Stress eating and tuning out: Cancer cells re-wire metabolism to counter stress

Contact Info

Product

Resources

About