Properties of Succinyl-Coenzyme A: d -Citramalate Coenzyme A Transferase and Its Role in the Autotrophic 3-Hydroxypropionate Cycle of Chloroflexus aurantiacus
| Autor: | Silke Friedmann, Georg Fuchs, Birgit E. Alber |
|---|---|
| Rok vydání: | 2006 |
| Předmět: |
Transcription
Genetic Coenzyme A Malates Glyoxylate cycle Gene Expression Microbiology Chloroflexus Substrate Specificity chemistry.chemical_compound Bacterial Proteins Hexosyltransferases Escherichia coli Transferase Lactic Acid RNA Messenger Cloning Molecular Molecular Biology chemistry.chemical_classification Binding Sites biology Chloroflexus aurantiacus Active site Succinates Lyase biology.organism_classification Enzymes and Proteins Recombinant Proteins Molecular Weight Protein Subunits RNA Bacterial Enzyme chemistry Biochemistry Genes Bacterial Multigene Family biology.protein Acyl Coenzyme A Coenzyme A-Transferases Dimerization |
| Zdroj: | Journal of Bacteriology. 188:6460-6468 |
| ISSN: | 1098-5530 0021-9193 |
| DOI: | 10.1128/jb.00659-06 |
| Popis: | The phototrophic bacterium Chloroflexus aurantiacus uses the 3-hydroxypropionate cycle for autotrophic CO 2 fixation. This cycle starts with acetyl-coenzyme A (CoA) and produces glyoxylate. Glyoxylate is an unconventional cell carbon precursor that needs special enzymes for assimilation. Glyoxylate is combined with propionyl-CoA to β-methylmalyl-CoA, which is converted to citramalate. Cell extracts catalyzed the succinyl-CoA-dependent conversion of citramalate to acetyl-CoA and pyruvate, the central cell carbon precursor. This reaction is due to the combined action of enzymes that were upregulated during autotrophic growth, a coenzyme A transferase with the use of succinyl-CoA as the CoA donor and a lyase cleaving citramalyl-CoA to acetyl-CoA and pyruvate. Genomic analysis identified a gene coding for a putative coenzyme A transferase. The gene was heterologously expressed in Escherichia coli and shown to code for succinyl-CoA: d -citramalate coenzyme A transferase. This enzyme, which catalyzes the reaction d -citramalate + succinyl-CoA → d -citramalyl-CoA + succinate, was purified and studied. It belongs to class III of the coenzyme A transferase enzyme family, with an aspartate residue in the active site. The homodimeric enzyme composed of 44-kDa subunits was specific for succinyl-CoA as a CoA donor but also accepted d -malate and itaconate instead of d -citramalate. The CoA transferase gene is part of a cluster of genes which are cotranscribed, including the gene for d -citramalyl-CoA lyase. It is proposed that the CoA transferase and the lyase catalyze the last two steps in the glyoxylate assimilation route. |
| Databáze: | OpenAIRE |
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