A primitive pathway of porphyrin biosynthesis and enzymology in Desulfovibrio vulgaris.
Culture of Desulfovibrio vulgaris in a medium supplemented with 5-aminolevulinic acid and L-methionine-methyl-d3 resulted in the formation of porphyrins (sirohydrochlorin, coproporphyrin III, and protoporphyrin IX) in which the methyl groups at the C-2 and C-7 positions were deuterated. A previously unknown hexacarboxylic acid was also isolated, and its structure was determined to be 12, 18-didecarboxysirohydrochlorin by mass spectrometry and 1H NMR. These results indicate a primitive pathway of heme biosynthesis in D. vulgaris consisting of the following enzymatic steps: (i) methylation of the C-2 and C-7 positions of uroporphyrinogen III to form precorrin-2 (dihydrosirohydrochlorin); (ii) decarboxylation of acetate groups at the C-12 and C-18 positions of precorrin-2 to form 12,18-didecarboxyprecorrin-2; (iii) elimination of acetate groups of the C-2 and C-7 positions of 12,18-didecarboxyprecorrin-2 to form coproporphyrinogen III; and (iv) conversion of coproporphyrinogen III to protoporphyrin IX via protoporphyrinogen IX. We isolated the following three enzymatic activities involved in steps i-iii from the soluble fraction of the cells by anion-exchange chromatography: S-adenosyl-L-methionine:uroporphyrinogen III methyltransferase, precorrin-2 12,18-acetate decarboxylase, and 12, 18-didecarboxyprecorrin-2 2,7-decarboxymethylase; all enzymic products were converted into autooxidized methyl esters and analyzed by thin-layer chromatography, UV-visible (UV-VIS) absorption, and mass spectrometry. The enzymatic reactions in D. vulgaris shed new light on porphyrin biosynthesis at an early stage in the evolution of prokaryotes.
Ishida
T
T
Department of Biochemistry, Molecular Neurobiology Research Center, Shiga University of Medical Science, Seta, Ohtsu, Shiga 520-21, Japan.
Yu
L
L
Akutsu
H
H
Ozawa
K
K
Kawanishi
S
S
Seto
A
A
Inubushi
T
T
Sano
S
S
D002855:Chromatography, Thin Layer; D003305:Coproporphyrinogens / Q000378:metabolism; D003470:Culture Media; D016969:Desulfovibrio vulgaris / Q000378:metabolism*; D007783:Lactones / Q000737:chemistry; D013058:Mass Spectrometry; D008970:Molecular Weight; D011166:Porphyrins / Q000096:biosynthesis* / Q000737:chemistry; D013053:Spectrophotometry; D014577:Uroporphyrinogens / Q000378:metabolism
D003305:Coproporphyrinogens; D003470:Culture Media; D007783:Lactones; D011166:Porphyrins; D014577:Uroporphyrinogens; C028026:coproporphyrinogen III