Moorella thermoacetica

Das A, R Silaghi-Dumitrescu, LG Ljungdahl, DM Kurtz (2005) Cytochrome bd oxidase, oxidative stress, and dioxygen tolerance of the strictly anaerobic bacterium Moorella thermoacetica. J Bacteriol 187 2020-2029. 

GoBner A, Devereux R, Ohnemtiller N, et al. 1999. Thermicanus aegyptius gen. nov., sp. nov., isolated from oxic soil, a facultative microaerophile that grows com-mensally with the thermophilic acetogen Moorella thermoacetica. Appl Environ Microbiol 65 5124-33. 

Electron-Transport Pathway Linked to the Use of Oxygen in Moorella thermoacetica... 

The acetogenic bacterium Moorella thermoacetica contains a cofactor comprising iron, sulfur, copper and nickel in the enzyme carbon monoxide dehyd-rogenase/acetyl-CoA, and Drennan et al. proposed a new role for Cu in biology on the basis of their structure determination at 2.2 A resolution.81 The Cu bridges the Fe4S4 cluster and Ni centre via three p2-S atoms, and hence the reported EPR... 

Carbon monoxide dehydrogenase/acetyl coenzyme A synthase (CODH/ACS) describes two different classes of enzymes carbon monoxide dehydrogenase (CODH) isolated from Rhodospirillum rubrum or Carboxydothermus hydrogenoformans reversibly oxidizes CO to CO2 according to equation (2), and the bifunctional CODH/ACS enzyme from Moorella thermoacetica catalyzes the reversible reduction of CO2 to CO (CODH) and acetyl coenzyme assembly/disassembly (ACS) (equation 3). ... 

There is yet another biochanical reaction involving CO (apart from its role as a transmitter substance in animals) which should be addressed here CO is activated and linked to some Ni-CH moiety in a [Ni(deprotonated ohgopeptide)(CH3)] complex attached to a Ni or Cu car-bonylpolythiolate complex which affords acetyl-CoA via some Ni acetyl system by CO shift and insertion in a manner very similar to the Monsanto process for production of acetic add from CO and methanol. The latter affords methyl groups attached to the metal (Ni here, Ru in the original Monsanto process). This transformation takes place in a Clostridium, namely Moorella thermoacetica. 

Selmee M and Su XD (2002) Crystal structure of an mRNA-bindingfragment of Moorella thermoacetica elongation factor SelB. EMBO J 21 4145-4153. 

Wang, S., Huang, H., Kahnt, J., and Thauer, R.K. (2013) A reversible electron-bifurcating ferredoxin- and NAD-dependent [FeFe]-hydrogenase (HydABQ in Moorella thermoacetica. /. Bacteriol, 195 (6), 1267-1275. 

Another novel candidate with NO reductase activity is a flavodiiron protein from Moorella thermoacetica [114]. Two genes of this strictly anaerobic, aceto-genic bacterium, namely and hrb, have no known function. FprA contains flavin mononucleotide (FMN) and a non-heme diiron site while Hrb contains FMN and a rubredoxin-like [Fe(SCys)4] site. The combination of Hrb and FprA exhibits NADH NO oxidoreductase activity. 

Fig. 11.21 a) The C-cluster reported for C hydrogenoformans CODH (note that the Ni ion is four-coordinated). b) The cluster of Moorella thermoacetica [157 -... 

FIGURE 16.3 The A cluster of ACS/CODH from Moorella thermoacetica. M is ably Ni, Cu, or Zn, Ni being the active form L is an unknown noi MOtein ligand. 

FDHs present in acetogens are known to take part in a carbon fixation metabolic pathway producing acetate (the Eastern branch of the Wood-Ljungdahl pathway), in which the first step involves reduction of CO2 to formate [76]. Several FDHs are known to catalyze CO2 reduction under appropriate conditions [77-81]. Those enzymes from acetogenic and related anaerobes, such as Moorella thermoacetica and Clostridium pasteurianum, are better than other FDHs as reduction catalysts but also show similar catalytic efficiency toward formate oxidation. 

Anaerobic bacteria such as Moorella thermoacetica have the capacity to fix carlxMi dioxide with carbon monoxide and hydrogen for the production of ethanol, acetic acid, and other useful chemicals. 

Another member of the family of diiron flavoproteins is the recently characterized A-type flavoprotein FprA from the anaerobic. Gram-positive acetogenic bacterium Moorella thermoacetica [607]. Similar to ROO, recombinant FprA also exists as a homodimer of 45-kDa subunits and may function both as an oxido and... 

Figure 38. Active site structure of nitric oxide reductase, metalloflavoprotein FprA from Moorella thermoacetica (A) oxidized FprA (PDB code 1YCF), and (B) reduced FprA (PDB code lYCG).

Silaghi-Dumitrescu R, Coulter ED, Das A, Ljungdahl LG, Jameson GNL, Huynh BH, Kurtz Jr DM. 2003. A flavodiiron protein and high molecular weight mbredoxin from Moorella thermoacetica with nitric oxide reductase activity. Biochemistry 42 2806-2815. 

Silaghi-Dumitrescu R, Kurtz Jr DM., Ljtmgdahl LG, Lanzilotta WN. 2005. X-ray crystal stmctures of Moorella thermoacetica FprA novel diiron site stmcture and mechanistic insights into a scavenging nitric oxide reductase. Biochemistry 44 6492-6501. 

FIGURE 16.5 The A cluster of ACS/CODH from Moorella thermoacetica. 

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