CbiZ, an amidohydrolase enzyme required for salvaging the coenzyme B12 precursor cobinamide in archaea
AUTOR(ES)
Woodson, Jesse D.
FONTE
National Academy of Sciences
RESUMO
The existence of a pathway for salvaging the coenzyme B12 precursor dicyanocobinamide (Cbi) from the environment was established by genetic and biochemical means. The pathway requires the function of a previously unidentified amidohydrolase enzyme that converts adenosylcobinamide to adenosylcobyric acid, a bona fide intermediate of the de novo coenzyme B12 biosynthetic route. The cbiZ gene of the methanogenic archaeon Methanosarcina mazei strain Göl was cloned, was overproduced in Escherichia coli, and the recombinant protein was isolated to homogeneity. HPLC, UV-visible spectroscopy, MS, and bioassay data established adenosylcobyric as the corrinoid product of the CbiZ-catalyzed reaction. Inactivation of the cbiZ gene in the extremely halophilic archaeon Halobacterium sp. strain NRC-1 blocked the ability of this archaeon to salvage Cbi. cbiZ function restored Cbi salvaging in a strain of the bacterium Salmonella enterica, whose Cbi-salvaging pathway was blocked. The salvaging of Cbi through the CbiZ enzyme appears to be an archaeal strategy because all of the genomes of B12-producing archaea have a cbiZ ortholog. Reasons for the evolution of two distinct pathways for Cbi salvaging in prokaryotes are discussed.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=373507Documentos Relacionados
- A New Pathway for Salvaging the Coenzyme B12 Precursor Cobinamide in Archaea Requires Cobinamide-Phosphate Synthase (CbiB) Enzyme Activity
- Biosynthesis of the corrin macrocycle of coenzyme B12 in Pseudomonas denitrificans.
- Identification of Cobamide Coenzyme in Nodules of Symbionts & Isolation of the B12 Coenzyme From Rhizobium meliloti12
- Coenzyme B12 riboswitches are widespread genetic control elements in prokaryotes
- B12 Coenzyme-dependent Ribonucleotide Reductase in Rhizobium Species and the Effects of Cobalt Deficiency on the Activity of the Enzyme1