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Haem biosynthesis in anaerobic organisms

ITQB researchers discover alternative pathway
Haem biosynthesis in anaerobic organisms

A haem group

Oeiras, 23.04.09

Haem cofactors are essential for the function of key proteins involved in a large array of metabolic processes. However, the enzymes involved in their biosynthesis remain uncharacterized in anaerobic organisms. To fill this gap the Molecular Genetics of Microbial Resistance Laboratory (and co-workers) recently characterized several of these proteins and the data provided insights for an alternative haem biosynthetic pathway present in some anaerobic bacteria and archaea. The results are published in the March issue of the Biochemical Journal.

The authors suggest that the production of the haem group in primitive anaerobic enviroments probably required a different set of enzymes and that only later, as molecular oxygen became more abundant, the pathway involving several oxidative steps in the synthesis of haems became the more common route.

Biochem. J. (2009) Immediate Publication, doi:10.1042/BJ20090151

Functional characterization of the early steps of tetrapyrrole biosynthesis and modification in Desulfovibrio vulgaris Hildenborough

Susana A. L. Lobo, Amanda Brindley, Martin J. Warren and Lígia M. Saraiva

The article reports the comprehensive analysis of the haem biosynthetic pathway in the environmentally important anaerobic organism D. vulgaris Hildenborough.

In summary, the research described in this paper outlines how the basic tetrapyrrole framework is synthesized up to the first branch point, which is proposed to be sirohydrochlorin. The identification of bifunctional CobA/HemD is consistent with uroporphyrinogen III not being a branch point in the bifurcated pathway and represents a useful marker for an alternative haem biosynthetic route, which has been previously hypothesized to occur in some Desulfovibrio species and archaea.



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