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Highlights d The class IIa HDAC, HDAC7, drives TLR4-inducible glycolysis in macrophages d An interaction between HDAC7 and PKM2 drives macrophage immunometabolic responses d Deacetylation of PKM2 at K433 licenses it to drive proinflammatory IL-1b expression d Multiple class IIa HDACs can engage the PKM2 immunometabolic signaling hub

An intracellular 3-hydroxybutyrate (3HB)-oligomer hydrolase (PhaZ2 Reu ) of Ralstonia eutropha was purified from Escherichia coli harboring a plasmid containing phaZ2 Reu . The purified enzyme hydrolyzed linear and cyclic 3HB-oligomers. Although it did not degrade crystalline poly(3-hydroxybutyrate) (PHB), the purified enzyme degraded artificial amorphous PHB at a rate similar to that of the previously identified intracellular PHB (iPHB) depolymerase (PhaZ1 Reu ). The enzyme appeared to be an endo-type hydrolase, since it actively hydrolyzed cyclic 3HB-oligomers. However, it degraded various linear 3HB-oligomers and amorphous PHB in the fashion of an exo-type hydrolase, releasing one monomer unit at a time. PhaZ2 was found to bind to PHB inclusion bodies and as a soluble enzyme to cell-free supernatant fractions in R. eutropha; in contrast, PhaZ1 bound exclusively to the inclusion bodies. When R. eutropha H16 was cultivated in a nutrient-rich medium, the transient deposition of PHB was observed: the content of PHB was maximized in the log growth phase (12 h, ca. 14% PHB of dry cell weight) and decreased to a very low level in the stationary phase (ca. 1% of dry cell weight). In each phaZ1-null mutant and phaZ2-null mutant, the PHB content in the cell increased to ca. 5% in the stationary phase. A double mutant lacking both phaZ1 and phaZ2 showed increased PHB content in the log phase (ca. 20%) and also an elevated PHB level (ca. 8%) in the stationary phase. These results indicate that PhaZ2 is a novel iPHB depolymerase, which participates in the mobilization of PHB in R. eutropha along with PhaZ1.Poly(3-hydroxybutyrate) (PHB), a homopolymer of R(Ϫ)-3-hydroxybutyrate (3HB), is a storage material produced by some bacteria under certain conditions (1). In the past few decades, the application of this biopolymer to biodegradable polymers or plastics has been studied extensively (12). In these studies, the extracellular metabolism of PHB has been clarified in many bacteria and some fungi (6, 7). However, only a few studies on the intracellular degradation of PHB have been published (13,14,17,19,20). An intracellular PHB (iPHB) depolymerase system in Rhodospirillum rubrum was first reported in 1964 and consisted of a thermostable activator and a thermolabile esterase (13). This system is still not well understood in spite of a recent reinvestigation (14). The molecular cloning of an iPHB depolymerase from Ralstonia eutropha H16 has been also reported (17). This enzyme (PhaZ1 Reu ) degraded artificial amorphous PHB granules but not crystalline PHB. A mutant lacking PhaZ1 Reu showed a higher PHB content compared to the wild-type in a nutrient-rich medium, but in this mutant the mobilization of PHB was not inhibited completely, suggesting that the cloned depolymerase gene is not the only gene responsible for the biodegradation of PHB in this bacterium (5, 17). In regard to this point, recently we found another esterase (PhaZ2 Reu ) that hydrolyzes 3HB-oligomers and cloned its gene (18). We examined the properties of the ...

A novel intracellular poly(3-hydroxybutyrate) (PHB) depolymerase (PhaZd) of Wautersia eutropha (formerly

NK cells play critical roles in protection against haematological malignancies but can acquire a dysfunctional state, which limits anti-tumour immunity. However, the underlying reasons for this impaired NK cell function remain to be uncovered. We found that NK cells in aggressive B cell lymphoma underwent substantial transcriptional reprogramming associated with increased lipid metabolism, including elevated expression of the transcriptional regulator PPAR-g. Exposure to fatty acids in the lymphoma environment potently suppressed NK cell effector response and cellular metabolism. NK cells from both diffuse large B cell lymphoma patients and Eµ-myc B cell lymphoma-bearing mice displayed reduced IFN-g production. Activation of PPAR-g partially restored mitochondrial membrane potential and IFN-g production. Overall our data indicate that increased lipid metabolism, while impairing their function, is a functional adaptation of NK cells to the fatty-acid rich lymphoma environment.