Identification and preliminary characterization of acsF, a Putative Ni-insertase used in the biosynthesis of acetyl-CoA synthase from Clostridium thermoaceticum
Journal Article
·
· Journal of Inorganic Biochemistry
OSTI ID:826202
- Texas A&M University
OAK-B135 The acsABCDE genes in the Clostridium thermoaceticum genome are used for autotrophic acetyl-CoA synthesis using the Wood/Ljungdahl pathway. A 2.8 kb region between acsC and acsD was cloned and sequenced. Two open reading frames, orf7 ({approx} 1.9 kb) and acsF ({approx} 0.7 kb) were identified. orf7 appears to encode an Fe-S protein, in that it contains 5 conserved cysteine residues, 3 of which are present in a motif (CXXXXXCXXC) 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, acsF is probably involved in this pathway. Sequence alignment of AcsF and 11 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 (ACSCt). However, this could not be established, as expression of acsF did not effect activation of recombinant AcsAB expressed in E. coli. Also, E. coli cells defective in hypB retained the ability to synthesize active recombinant AcsAB. Rather, the concentration of extracellular Ni2+ ions was critical to activation.
- Research Organization:
- Texas A& M University, College Station, TX (US)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER); Office of Energy Research; basic biological sciences (US)
- DOE Contract Number:
- FG03-01ER15177
- OSTI ID:
- 826202
- Report Number(s):
- DOE/ER/15177-2
- Journal Information:
- Journal of Inorganic Biochemistry, Journal Name: Journal of Inorganic Biochemistry Journal Issue: 1-2 Vol. 93
- Country of Publication:
- United States
- Language:
- English
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