Summary Pyruvate dehydrogenase kinases (PDK1–4) inhibit the TCA cycle by phosphorylating pyruvate complex (PDC). Here, we show that PDK family is dispensable for murine embryonic development and BCKDK serves as a compensatory mechanism inactivating PDC. First, knocked out all four Pdk genes one one. Surprisingly, total KO embryos developed were born in expected ratios but died p...

Synechococcus sp. PCC 7002 is a unicellular cyanobacterium capable of fast growth and tolerance to high light intensity salinity. These attributes along with genetic tractability make an attractive candidate for industrial scale production specialty commodity chemicals. LS (Davies et al., Front Bioeng Biotechnol, 2014, 2, 21–11) produces limonene, energy dense diesel jet fuel drop-in additive, ...

We have characterized the gene YOR347c of Saccharomyces cerevisiae and shown that it encodes a second functional pyruvate kinase isoenzyme, Pyk2p. Overexpression of the YOR347c/PYK2 gene on a multicopy vector restored growth on glucose of a yeast pyruvate kinase 1 (pyk1) mutant strain and could completely substitute for the PYK1-encoded enzymatic activity. PYK2 gene expression is subject to glu...

A reversible interconversion of two kinetically distinct forms of hepatic pyruvate kinase regulated by glucagon and insulin is demonstrated in the perfused rat liver. The regulation does not involve the total enzyme content of the liver, but rather results in a modulation of the substrate dependence. The forms of pyruvate kinase in liver homogenates are distinguished by measurements of the rati...

Group N streptococci, which have the lactose phosphoenolpyruvate (PEP)-dependent phosphotransferase system (PTS) and phospho-beta-d-galactosidase (beta-Pgal), grew rapidly on lactose and converted more than 90% of the sugar to l-lactate. In contrast, Streptococcus lactis 7962, which does not have a beta-Pgal, grew slowly on lactose and converted only 15% of the sugar to l-lactate. With glucose ...

The influence of various adrenergic agonists and antagonists on pyruvate kinase activity and lactate production from endogenous glycogen reserves was investigated in hepatocytes isolated from young and old rats. With hepatocytes prepared fromjuvenile rats (100 to 150 g) 10 PM epinephrine and 10 pM isoproterenol (a padrenergic agonist) inhibit pyruvate kinase activity and lactate production; whe...

In a previous phylogenetic study of the family of pyruvate kinase EC (2.7.1.40), a cluster with Glu117 and another with Lys117 were found (numbered according to the rabbit muscle enzyme). The sequences with Glu117 have been found to be K+-dependent, whereas those with Lys117 were K+-independent. Interestingly, only γ-proteobacteria exhibit sequences in both branches of the tree. In this context...

The enzymic activity of the mammalian pyruvate dehydrogenase complex is regulated by the phosphorylation of three serine residues (sites 1, 2 and 3) located on the E1 component of the complex. Here we report that the four isoenzymes of protein kinase responsible for the phosphorylation and inactivation of pyruvate dehydrogenase (PDK1, PDK2, PDK3 and PDK4) differ in their abilities to phosphoryl...

Insulin treatment of adipocytes increased the amount or activity of a low molecular weight, acid-stable material which, when isolated from intact adipocytes by heat extraction and subsequent Sephadex G25 chromatography, yielded a single active fraction that stimulated mitochondrial pyruvate dehydrogenase by activating the phosphatase and not by altering the kinase activity. Phosphatase activati...