Revisiting the glyoxylate cycle: alternate pathways for microbial acetate assimilation

  title={Revisiting the glyoxylate cycle: alternate pathways for microbial acetate assimilation},
  author={Scott A. Ensign},
  journal={Molecular Microbiology},
  • S. Ensign
  • Published 1 July 2006
  • Biology
  • Molecular Microbiology
The glyoxylate cycle, identified by Kornberg et al. in 1957, provides a simple and efficient strategy for converting acetyl‐CoA into anapleurotic and gluconeogenic compounds. Studies of a number of bacteria capable of growth with C2 compounds as the sole carbon source have revealed that they lack the key glyoxylate cycle enzyme isocitrate lyase, suggesting that alternative pathway(s) for acetate assimilation exist in these bacteria. Recent studies of acetate assimilation in methylotrophs and… 
The Enzymology of Sugar Metabolism in Sulfolobus solfataricus
The results presented show that a separate C5 dehydratase exists, completing the first part of a non-phosphorylative C5 pathway, and that the subsequent enzymes required for glycolaldehyde metabolism are present and active during growth on C5 sugars.
Heterotrophic metabolism on substrates other than glucose
In this chapter, the bacterial metabolism of organic compounds other than glucose is discussed, and it is described previously how glucose and mineral salts can support the growth of certain heterotrophs.
Mesaconyl-Coenzyme A Hydratase, a New Enzyme of Two Central Carbon Metabolic Pathways in Bacteria
A similar yet distinct class of enzymes containing only one hydratase domain was found in various other bacteria, such as Streptomyces species, and the role of this widely distributed new enzyme is discussed.
Comparative Genomics of Members of the Genus Defluviicoccus With Insights Into Their Ecophysiological Importance
The whole genome sequence of the type strain Defluviicoccus vanusT is described and 16S rRNA and genome sequence data suggest that the current recognition of four clades is insufficient to embrace their phylogenetic biodiversity, but do not support the view that they should be re-classified into families other than their existing location in the Rhodospirillaceae.
Carbon Metabolic Pathways in Phototrophic Bacteria and Their Broader Evolutionary Implications
Diverse CO2 assimilation pathways, acetate assimilation, carbohydrate catabolism, the tricarboxylic acid cycle and some key, and/or unconventional enzymes in central carbon metabolism of phototrophic microorganisms are reviewed.
Production of Hydrogen and 5-Aminolevulinic Acid by Photosynthetic Bacteria from Palm Oil Mill Effluent
Research directed towards development of processes to produce hydrogen from palm oil mill effluent (POME) revealed that, following the application of existing biotreatment processes, there were


Study of an alternate glyoxylate cycle for acetate assimilation by Rhodobacter sphaeroides
Results as well as identification of acetate‐upregulated proteins by two‐dimensional gel electrophoresis lead to the proposal of a new pathway for acetate assimilation.
Glyoxylate Regeneration Pathway in the Methylotroph Methylobacterium extorquens AM1
It is shown that methylmalonyl-CoA mutase, an R-specific crotonase, isobutyryl- coenzyme A dehydrogenase, and a GTPase are involved in glyoxylate regeneration.
Identification of Genes Involved in the Glyoxylate Regeneration Cycle in Methylobacterium extorquens AM1, Including Two New Genes, meaC and meaD
The glyoxylate regeneration cycle (GRC) operates in serine cycle methylotrophs to effect the net conversion of acetyl coenzyme A to glyoxylene, and phenotypic analysis has been carried out to clarify their role in this cycle.
A proposed citramalate cycle for acetate assimilation in the purple non‐sulfur bacterium Rhodospirillum rubrum
During phototrophic growth on acetate and CO2Rhodospirillum rubrum 2R contained malate synthase but lacked isocitrate lyase, and the existence in R. rubrum of a CO2-dependent cyclic pathway of acetate oxidation to glyoxylate with citramalate as an intermediate is proposed.
The formation of isocitratase by the Athiorhodaceae.
The glyoxylate cycle cannot account for net synthesis of cell constituents from acetate or acetate precursors in these latter two organisms, and isocitratase is formed by Rhodopseudomonas palustris and R. capsulatus.
Acetate metabolism in Rhodopseudomonas gelatinosa and several other Rhodospirillaceae
When Rhodopseudomonas gelatinosa was grown on acetate aerobically in the dark both enzymes of the glyoxylate bypass, isocitrate lyase and malate synthase, could be detected. However, under anaerobic
The glyoxylate cycle as a stage in the conversion of fat to carbohydrate in castor beans.
l-Malyl-Coenzyme A/β-Methylmalyl-Coenzyme A Lyase Is Involved in Acetate Assimilation of the Isocitrate Lyase-Negative Bacterium Rhodobacter capsulatus
It is proposed that L-malyl-CoA/beta-methylmalyl -CoA lyase encoded by mcl1 is involved in acetate assimilation by R. capsulatus and possibly other glyoxylate cycle-negative bacteria.
Mixotrophic growth of Thiobacillus A2 on acetate and thiosulfate as growth limiting substrates in the chemostat
The results of 14C-acetate assimilation experiments and of gas-analysis demonstrated that the extent to which acetate was assimilated depended also on the substrate ratio in the inflowing medium, under the different growth conditions surprisingly little variation was found in some tri-carboxylic acid cycle enzyme activities.