RT Journal Article
SR Electronic
T1 Mesaconyl-Coenzyme A Hydratase, a New Enzyme of Two Central Carbon Metabolic Pathways in Bacteria
JF Journal of Bacteriology
JO J. Bacteriol.
FD American Society for Microbiology
SP 1366
OP 1374
DO 10.1128/JB.01621-07
VO 190
IS 4
A1 Zarzycki, Jan
A1 Schlichting, Ansgar
A1 Strychalsky, Nina
A1 Müller, Michael
A1 Alber, Birgit E.
A1 Fuchs, Georg
YR 2008
UL http://jb.asm.org/content/190/4/1366.abstract
AB The coenzyme A (CoA)-activated C5-dicarboxylic acids mesaconyl-CoA and β-methylmalyl-CoA play roles in two as yet not completely resolved central carbon metabolic pathways in bacteria. First, these compounds are intermediates in the 3-hydroxypropionate cycle for autotrophic CO2 fixation in Chloroflexus aurantiacus, a phototrophic green nonsulfur bacterium. Second, mesaconyl-CoA and β-methylmalyl-CoA are intermediates in the ethylmalonyl-CoA pathway for acetate assimilation in various bacteria, e.g., in Rhodobacter sphaeroides, Methylobacterium extorquens, and Streptomyces species. In both cases, mesaconyl-CoA hydratase was postulated to catalyze the interconversion of mesaconyl-CoA and β-methylmalyl-CoA. The putative genes coding for this enzyme in C. aurantiacus and R. sphaeroides were cloned and heterologously expressed in Escherichia coli, and the proteins were purified and studied. The recombinant homodimeric 80-kDa proteins catalyzed the reversible dehydration of erythro-β-methylmalyl-CoA to mesaconyl-CoA with rates of 1,300 μmol min−1 mg protein−1. Genes coding for similar enzymes with two (R)-enoyl-CoA hydratase domains are present in the genomes of Roseiflexus, Methylobacterium, Hyphomonas, Rhodospirillum, Xanthobacter, Caulobacter, Magnetospirillum, Jannaschia, Sagittula, Parvibaculum, Stappia, Oceanicola, Loktanella, Silicibacter, Roseobacter, Roseovarius, Dinoroseobacter, Sulfitobacter, Paracoccus, and Ralstonia species. A similar yet distinct class of enzymes containing only one hydratase domain was found in various other bacteria, such as Streptomyces species. The role of this widely distributed new enzyme is discussed.