Enzymology of the pathway for ATP production by arginine breakdown

Abstract

In cells, the breakdown of arginine to ornithine and ammonium ion plus carbon dioxide is coupled to the generation of metabolic energy in the form of ATP. The arginine breakdown pathway is minimally composed of arginine deiminase, ornithine transcarbamoylase, carbamate kinase, and an arginine/ornithine antiporter; ammonia and carbon dioxide most likely diffuse passively across the membrane. The genes for the enzymes and transporter have been cloned and expressed, and the proteins have been purified from Lactococcus lactis IL1403 and incorporated into lipid vesicles for sustained production of ATP. Here, we study the kinetic parameters and biochemical properties of the individual enzymes and the antiporter, and we determine how the physicochemical conditions, effector composition, and effector concentration affect the enzymes. We report the KM and VMAX values for catalysis and the native oligomeric state of all proteins, and we measured the effect of pathway intermediates, pH, temperature, freeze–thaw cycles, and salts on the activity of the cytosolic enzymes. We also present data on the protein‐to‐lipid ratio and lipid composition dependence of the antiporter.

Neuroinflammation, Sleep, and Circadian Rhythms

“…There are three forms of NOS including neuronal NOS (nNOS), endothelial NOS (eNOS) and inducible NOS (iNOS) that are produced by neurons, endothelial cells, and microglia in the brain ( Costa et al., 2016 ). Arginine is produced from citrulline in arginine and proline metabolism and consumes ATP in the process ( Pols et al., 2021 ). Citrulline is produced by several mechanisms including from the byproduct of arginine and NOS and glutamine and glutamate ( Swamy et al., 2010 ).…”

Pegylated arginine deiminase drives arginine turnover and systemic autophagy to dictate energy metabolism

“…arcA encodes a high-affinity arginine deiminase 23 that differs from the arginases in its enzymatic products, citrulline and ammonia. 22 We delivered arcA or eGFP (an ectopic expression control vector) via tail-vein injection of AAV8 encoding arcA or eGFP under hepatocyte-specific thyroxine binding globulin promoter control in 5-week-old db/db mice. Five weeks following gene delivery, we verified arcA expression ( Figure S1 A) and subjected all mice to a battery of metabolic assays and tissue collection ( Figure 1 A).…”

“…Here, we demonstrate a target process, arginine catabolism, and commandeer a naturally occurring bacterial virulence factor to leverage this process. Specifically, we show that the high-affinity arginine deiminase, 22 arcA, enhances host arginine catabolism to activate key hepatocyte fasting-like signals and systemic autophagic flux to ameliorate multiple metabolic complications in obese mice. We then nominate ADI-PEG 20 to drive these processes exogenously.…”

“…arcA is a bacterial virulence factor that is evolutionarily primed for this duty, because its high binding affinity for ARG2 (K m = 34.5 μM) permits bacterial niche establishment by competing arginine away from host inflammatory nitric oxide synthases and toward bacterial ATP production. 22 The favorable enzymatic properties of arcA and the ready availability of a pharmacotherapy that mimics these properties led us to examine efficacy and mechanisms of therapeutic arginine catabolism against obesity and its complications.…”

Biodiversity of wild Lactococcus lactis and their geo-spatial relationship with the environment

“…On the other hand, adaptive evolution has been extensively used in stress physiological studies of LABs, specially undergo a variety of environmental stresses, such as heat, salt and acid stress. Systems biology methods including omics analysis also have allowed us to understand how LAB respond to environmental changes, and other variables should be considered for the study of LABs communities e.g., temporal and spatial change of community composition due to biotic/abiotic factors (Larsen et al 2008, Wenzel et al 2018, Jensen et al 2019, Van der Meulen et al 2019, Pols et al 2020.…”