Dehydrogenase, carbon monoxide

The C-cluster of ACS/CODH displays two EPR signals with of 1.82 (also called Credl) and 1.86 (Cred2). It has been suggested that Credl is 2 e more oxidized than Cred2 [161,162] and that both states are involved in catalysis. 

Thus the C. hydrogmofoTTmm structure strongly suggests that, as the observed SH , OH should bridge Ni and Fe. Since the Ni ion has square planar coordina- 

The substrate/product CO2 binds to clusters in both Credl and Cred2 states. However, the binding must be different in the two cases because CO2 does not affect the g = 1.86 signal but it does modify g = 1.82 [162]. The simplest interpretation is that CO2 binds terminally to tetrahedral Ni(0) and it bridges Ni and Fe in Credl, when Ni is square planar Ni(II). 

---

Iron Sulfur Compounds. Many molecular compounds (18—20) are known in which iron is tetrahedraHy coordinated by a combination of thiolate and sulfide donors. Of the 10 or more stmcturaHy characterized classes of Fe—S compounds, the four shown in Figure 1 are known to occur in proteins. The mononuclear iron site REPLACE occurs in the one-iron bacterial electron-transfer protein mbredoxin. The [2Fe—2S] (10) and [4Fe—4S] (12) cubane stmctures are found in the 2-, 4-, and 8-iron ferredoxins, which are also electron-transfer proteins. The [3Fe—4S] voided cubane stmcture (11) has been found in some ferredoxins and in the inactive form of aconitase, the enzyme which catalyzes the stereospecific hydration—rehydration of citrate to isocitrate in the Krebs cycle. In addition, enzymes are known that contain either other types of iron sulfur clusters or iron sulfur clusters that include other metals. Examples include nitrogenase, which reduces N2 to NH at a MoFe Sg homocitrate cluster carbon monoxide dehydrogenase, which assembles acetyl-coenzyme A (acetyl-CoA) at a FeNiS site and hydrogenases, which catalyze the reversible reduction of protons to hydrogen gas. 

Sequence Comparison Between the N-Terminal Part of the Fepr Genes from Desulfovibrio desulfuricans (Dd) and Desulfovibrio vulgaris (Dv), Carbon Monoxide Dehydrogenase from Methanothrix soehngenii (Ms), Methanosarcina frisia Gdl (Mf), Clostridium thermoaceticum (Ct), Rhodospirillum rubrum (Rr), and Anaerobic Ribonucleotide Reductase from Escherichia coli (Ec) ... 

The carbon monoxide dehydrogenase of the aerobe Oligotropha carboxidovorans contains both Cu and Mo in the form of a cluster in which the Mo is bound to the thiol groups of molybdopterin cytosine nucleotide, and the Cu to cysteine residue in the form of a Cu-S-Mo(=0)OFl cluster (Dobbek et al. 2002). 

Dobbek H, V Svetlitchnyi, L Gremer, R Huber, O Meyer (2001) Crystal structure of a carbon monoxide dehydrogenase reveals a [Ni-4Fe-5S] cluster. Science 293 1281-1285. 

Drake HL. S-1 Hu, HG Wood (1980) Purification of carbon monoxide dehydrogenase, a nickel enzyme from Clostridium thermoaceticum. J Biol Chem 255 7174-7180. 

Drennan CL, J Heo, MD Sintchak, E Schreiter, PW Ludden (2001) Life on carbon monoxide x-ray structure of Rhodospirillum rubrum Ni-Fe-S carbon monoxide dehydrogenase. Proc Natl Acad Sci USA 98 11973-11978. 

Lu W-P, PE Jablonski, M Rasche, JG Ferry, SW Ragsdale (1994) Characterization of the metal centers of the Ni/Fe-S component of the carbon-monoxide dehydrogenase enzyme complex of Methanosarcina ther-mophila. J Biol Chem 269 9736-9742. 

Svetlitchnyi V, C Peschel, G Acker, O Meyer (2001) Two membrane-associated NiFeS-carbon monoxide dehydrogenases from the anaerobic carbon-monoxide-utilizing eubacterium Carboxydothermus hydrogeno-formans. J Bacterial 183 5134-5144. 

Huang S, PA Lindahl, C Wang, GN Bennett, EB Rudolph, JB Hughes (2000) 2,4,6-trinitrotolnene reduction by carbon monoxide dehydrogenase from Clostridium thermoaceticum. Appl Environ Microbiol 66 1474-1478. 

Carbon monoxide dehydrogenase active site CO oxidation / CO, reduction... 

Figure 2 Structures of the actrive sites of metalloenzymes containing metal-sulfur cluster units, (a) Fe only hydrogenase, H-cluster (Hoxfarm) (b) Sulfite reductase (c) NiFe carbon monoxide dehydrogenase, C-cluster and (d) NiFe carbon monoxide dehydrogenase, A-cluster, which functions as acetyl-CoA synthase...

Drennan, C.L., Doukov, T.I. and Ragsdale, S.W. (2004) The metalloclusters of carbon monoxide dehydrogenase/acetyl-CoA synthase a story in pictures, J. Biol. Inorg. Client.. 9, 511-515. 

Xia J, Hu Z, Popescu CV, et al. 1997. Mossbauer and EPR study of the Ni-activated a-subunit of carbon monoxide dehydrogenase from Clostridium thermoaceticum. J Am Chem Soc 119 8301-12. 

Hydrogenases are not the only nickel-containing enzyme, and researchers must therefore compare the maturation of different nickel proteins to obtain an integrated picture of nickel metabolism. Indeed, similarities between some of the hydrogenase-related nickel-processing proteins with urease and carbon monoxide dehydrogenase maturation factors have been noted, and this has facilitated interpretations of the results for... 

Kerby RL, Ludden PW, Roberts GD. 1997. In vivo nickel insertion into the carbon monoxide dehydrogenase of Khodospirillum rubrum molecular and physiological characterization of cooCTJ. J Bacteriol 179 2259-66. 

---