Identification and preliminary characterization of AcsF, a putative Ni-insertase used in the biosynthesis of acetyl-CoA synthase from Clostridium thermoaceticum
| Autor: | Paul A. Lindahl, Huay-Keng Loke |
|---|---|
| Rok vydání: | 2003 |
| Předmět: |
ATPase
Molecular Sequence Data Acetate-CoA Ligase Sequence alignment Biochemistry Inorganic Chemistry chemistry.chemical_compound Adenosine Triphosphate Bacterial Proteins Biosynthesis Acetyl Coenzyme A Nickel Amino Acid Sequence Cloning Molecular Clostridium ATP synthase biology Hydrolysis Acetyl-CoA Rhodospirillum rubrum biology.organism_classification Open reading frame chemistry Genes Bacterial biology.protein Sequence Alignment Carbon monoxide dehydrogenase |
| Zdroj: | Journal of Inorganic Biochemistry. 93:33-40 |
| ISSN: | 0162-0134 |
| Popis: | The acs ABCDE genes in the Clostridium thermoaceticum genome are used for autotrophic acetyl-CoA synthesis using the Wood–Ljungdahl pathway. A 2.8-kb region between acs C and acs D was cloned and sequenced. Two open reading frames, orf 7 (∼1.9 kb) and acs F (∼0.7 kb) were identified. orf 7 appears to encode an Fe–S protein, in that it contains five conserved cysteine residues, three of which are present in a motif (CGGXXXCGXC) commonly used to coordinate Fe–S clusters. However, Orf7 is probably not involved in autotrophic acetyl-CoA synthesis, as homologous genes are present in organisms that do not utilize this pathway and are absent in many that do. In contrast, acs F is probably involved in this pathway. Sequence alignment of AcsF and eleven homologs reveals a number of conserved regions, including a P-loop that binds nucleoside triphosphates and catalyzes their hydrolysis. One homolog is CooC, an ATPase/GTPase that inserts Ni into a precursor form of the C-cluster of the carbon monoxide dehydrogenase (CODH) from Rhodospirillum rubrum . Purified AcsF lacked Ni and Fe, and slowly catalyzed the hydrolysis of ATP. Such similarities to CooC suggest that AcsF may function to insert Ni into a Ni-deficient form of the bifunctional acetyl-CoA synthase/CODH from C. thermoaceticum (ACS Ct ). However, this could not be established, as expression of acs F did not effect activation of recombinant AcsAB expressed in E. coli . Also, E. coli cells defective in hyp B retained the ability to synthesize active recombinant AcsAB. Rather, the concentration of extracellular Ni 2+ ions was critical to activation. |
| Databáze: | OpenAIRE |
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