Carbon isotope fractionation during cis-trans isomerization of unsaturated fatty acids in Pseudomonas putida.
The molecular mechanism of the unique cis to trans isomerization of unsaturated fatty acids in the solvent-tolerant bacterium Pseudomonas putida S12 was studied. For this purpose, the carbon isotope fractionation of the cis-trans isomerase was estimated. In resting cell experiments, addition of 3-nitrotoluene for activation of the cis-trans isomerase resulted in the conversion of the cis-unsaturated fatty acids into the corresponding trans isomers. For the conversion of C16:1 cis to its corresponding trans isomer, a significant fractionation was measured. The intensity of this fractionation strongly depended on the rate of cis-trans isomerization and the added concentration of 3-nitrotoluene, respectively. The presence of a significant fractionation provides additional indication for a transition from the sp carbon linkage of the cis-double bond to an intermediate sp3 within an enzyme-substrate complex. The sp2 linkage is reconstituted after rotation to the trans configuration has occurred. As cytochrome c plays a major role in the catabolism of Cti polypeptide, these findings favour a mechanism for the enzyme in which electrophilic iron (Fe(3+)), provided by a heme domain, removes an electron of the cis double bond thereby transferring the sp2 linkage into sp3.
Heipieper
Herman J
HJ
Department of Bioremediation, Centre for Environmental Research (UFZ) Leipzig-Halle, Permoserstr. 15, 04318 Leipzig, Germany. hermann.heipieper@ufz.de
Neumann
Grit
G
Kabelitz
Nadja
N
Kastner
Matthias
M
Richnow
Hans Hermann
HH
D001665:Binding Sites; D002247:Carbon Isotopes; D045304:Cytochromes c / Q000378:metabolism; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D007536:Isomerism; D016958:Pseudomonas putida / Q000378:metabolism*; D019745:cis-trans-Isomerases / Q000378:metabolism*
D002247:Carbon Isotopes; D005231:Fatty Acids, Unsaturated; D045304:Cytochromes c; D019745:cis-trans-Isomerases