The corrinoid from Methanobacterium thermoautotrophicum (Marburg strain). Spectroscopic structure analysis and identification as Cobeta-cyano-5'-hydroxybenzimidazolyl-cobamide (factor III)

Abstract

The corrinoids from Methanobacterium thermoautotrophicum were extracted as the Co-cyano derivative, which was isolated in crystalline form. A consistent set of spectroscopic data was acquired (ultraviolet/visible, circular dichroic, infrared, fast-atom-bombardment mass, 'H-NMR and ' 3C-NMR spectra), which allowed the structural analysis of this complete corrinoid. It was assigned the structure of the Coo-cyano-5'-hydroxybenzimidazolylcobamide and was identified with Friedrich and Bernhauer's 'factor 111' by comparison with an authentic sample.Methanogenic bacteria contain considerable amounts of cobalt corrinoids, structurally related to vitamin B12 [I -81. The function of these in bacterial metabolism in part still is unclear (see e.g. [9]). In Methanobacterium thermoautotrophicum, they participate in the assembly of the coenzyme-Abound acetyl group (bacterial 'acetate' synthesis) from Hz and COz and from other C1 components [lo, 111, possibly via an acetyl-corrinoid intermediate [12, 131. In Methanosarcina barkeri, corrinoid-containing proteins act as methyltransferases in CH4 formation from CH30H [14] and probably from CH,COOH [15]. They also play a second, less-defined role in the synthesis of CH4 [2, 16, 171.A thorough structural analysis of the corrinoid from M . thermoautotrophicum appeared in place, since recently a strongly stimulating effect of vitamin B12 was found on the synthesis of methane in Methanobacterium bryantii [16] and in M . thermoautotrophicum [17], presumed to be associated with the redox properties of the corrinoids [16, 171. Secondly, a cobamide-containing membrane protein complex was also isolated from M . thermoautotrophicum by Schulz and Fuchs [I 81, who suggested that this protein complex plays an 'important and novel role in the growth of methanogenic bacteria from C 0 2 and H2'.The corrinoids from two methanogens, M . bryantii [8] and M . barkeri [4, 5, 191, have already been analyzed in their Cocyano form and identified as Coo-cyano-5'-hydroxybenzimidazolyl-cobamide ('factor 111' [20]). This was achieved by ultraviolet/visible spectral analysis [8], by spectrophotometric comparison with authentic material [4] and by a correlation of the ultraviolet/vissible spectroscopic of the complete corrinoid, complemented by an HPLC and 'H-NMR spectroscopic analysis of hydrolytic degradation products that were identified as the mixture of isomeric cyano-aquocobinamides, as 5-hydroxybenzimidazole and 1-a-D-ribofu- ranosyl-5-hydroxybenzimidazole [5, 191).Factor 111 was first isolated and separated from other complete corrinoids from sewage sludge by Friedrich and Bernhauer [20]. Its structure then was assigned by ultraviolet/ visible spectral analysis, by degradation and identification of the fragments cobinamide and 5-hydroxybenzimidazole [21], as well as by locating the position of the phenolic hydroxysubstituent of the benzimidazole-nucleotide [22]. However, it appears that, to date, a consistent structural analysis of intact factor 111 by spectroscopic means is still lacking.We report...

Purification, characterization, and molecular cloning of S-adenosyl-L-methionine: uroporphyrinogen III methyltransferase from Methanobacterium ivanovii

“…B12 factor III) (24,33,34,42,46) and Coa-t[-(7-adenyl)]cobamide (pseudovitamin B12) (24,43). Occurrence of cobinamide (factor B) has also been reported in Methanosarcina barkeri (29).…”

“…The encoded polypeptide showed more than 40% strict homology with P. denitrificans SUMT. The M. ivanovii SUMT structural gene is likely to be, as is P. denitrificans cobA, involved in corrinoid synthesis.Methanogenic bacteria synthesize particular types of corrinoids, mainly 5-hydroxybenzimidazolylcobamide (vitamin B12 factor III) (24,33,34,42,46) and Coa-t[-(7-adenyl)]cobamide (pseudovitamin B12) (24,43). Occurrence of cobina-…”

Purification and properties of N5‐methyltetrahydromethanopterin: coenzyme M methyltransferase from Methanobacterium thermoautotrophicum

“…5-Hydroxybenzimidazolyl cobamide was used as standard (Krautler et al, 1987) for which an absorption coefficient difference A&368--412 of 23.15 mM-' 3 cm-' was determined. The corrinoid content of enzyme samples was also assayed indirectly via analysis of the cobalt content by atomic absorption spectroscopy using the graphite tube technique and the Zeeman-effect background correction.…”

5′‐Methylbenzimidazolyl‐cobamides are the corrinoids from some sulfate‐reducing and sulfur‐metabolizing bacteria

“…In addition, growing cultures of M . thermoautotrophicum also can take up exogeneously supplied vitamin B12 and transform it into their own corrinoids (such as 4 [16]) presumably by an exchange of the base as an a-nucleoside [13]. Remarkably, the growth rate of this organism appeared little affected in the presence of 5,6-dimethyl-benzimidazole, when 5',6'-dimethylbenzimidazolyl-cobamides were biosynthesised by it instead of the 5'-hydroxybenzimidazolylcobamides [13].…”