The goal of this study was to test the relationship between malonyl-CoA concentration and its turnover measured in isolated rat hearts perfused with NaH(13)CO(3). This turnover is a direct measurement of the flux of acetyl-CoA carboxylation in the intact heart. It also reflects the rate of malonyl-CoA decarboxylation, i.e. the only known fate of malonyl-CoA in the heart. Conditions were selecte...

BACKGROUND Malonyl-coenzyme A (CoA) is an important biosynthetic precursor in vivo. Although Escherichia coli is a useful organism for biosynthetic applications, its malonyl-CoA level is too low. RESULTS To identify strains with the best potential for enhanced malonyl-CoA production, we developed a whole-cell biosensor for rapidly reporting intracellular malonyl-CoA concentrations. The biosen...

Obesity is an important contributor to the risk of developing insulin resistance, diabetes, and heart disease. Alterations in tissue levels of malonyl-CoA have the potential to impact on the severity of a number of these disorders. This review will focus on the emerging role of malonyl-CoA as a key "metabolic effector" of both obesity and cardiac fatty acid oxidation. In addition to being a sub...

Malonyl-CoA inhibits the carnitine-dependent transport of activated fatty acids into mitochondria by inhibiting the outer carnitine palmitoyltransferase (McGarry et al., 1978). Recent studies in several laboratories have shown that malonyl-CoA is not an ordinary competitive inhibitor of the enzyme. Liver mitochondria from fasted or diabetic rats are less inhibited by malonyl-CoA than are mitoch...

The central nervous system mediates energy balance (energy intake and energy expenditure) in the body; the hypothalamus has a key role in this process. Recent evidence has demonstrated an important role for hypothalamic malonyl CoA in mediating energy balance. Malonyl CoA is generated by the carboxylation of acetyl CoA by acetyl CoA carboxylase and is then either incorporated into long-chain fa...

Hypothalamic fatty acid metabolism is involved in central nervous system controls of feeding and energy balance. Malonyl-CoA, an intermediate of fatty acid biosynthesis, is emerging as a significant player in these processes. Notably, hypothalamic malonyl-CoA has been implicated in leptin's feeding effect. Leptin treatment increases malonyl-CoA level in the hypothalamic arcuate nucleus (Arc), a...

Insulin resistance in skeletal muscle is present in humans with type 2 diabetes (non-insulin dependent diabetes mellitus) and obesity and in rodents with these disorders. Malonyl CoA is a regulator of carnitine palmitoyl transferase l (CAP I), the enzyme that controls the transfer of long chain fatty acyl CoA into mitochondria, where it is oxidized. In rat skeletal muscle, the formation of malo...

The brain plays an important role in the regulation of energy balance in higher animals. Global energy balance is monitored by sets of neurons in the hypothalamus that respond to peripheral hormonal and afferent neural signals that sense the energy status. Malonyl-CoA, an intermediate in the biosynthesis of fatty acids, appears to function in this hypothalamic energy-sensing system. The steady-...

The kinetics of carnitine palmitoyltransferase I (CPT I; EC 2.3.1.21) were examined in mitochondria from rat liver, heart and skeletal muscle as a function of pH over the range 6.8-7.6. In all three tissues raising the pH resulted in a fall in the Km for carnitine, no change in the Km for palmitoyl-CoA or Octanoyl-CoA, and a marked decrease in the inhibitory potency of malonyl-CoA. Studies with...

Rates of ketogenesis in mitochondria from fed or starved rats were identical at optimal substrate concentrations, but responded differently to inhibition by malonyl-CoA. Kinetic data suggest that the K1 for malonyl-CoA is greater in the starved animal. These results indicate that, for the regulation of ketogenesis in the starved state, the lower sensitivity of carnitine palmitoyltransferase to ...