Cis–Trans Isomerase of Unsaturated Fatty Acids: An Immediate Bacterial Adaptive Mechanism to Cope with Emerging Membrane Perturbation Caused by Toxic Hydrocarbons
A rather efficient solvent adaptation mechanism enabling several gram-negative bacteria to tolerate and grow in the presence of membrane-disturbing compounds is the isomerization of cis- to trans-unsaturated membrane fatty acids. The degree of isomerization obviously depends on the toxicity and the concentration of membrane-affecting agents. Synthesis of trans-fatty acids comes about by direct isomerization of the respective cis-configuration of the double bond without shifting the position. The purpose of the conversion of the cis-configuration to trans is apparently the rapid adaptation of the membrane fluidity to rising temperature or the presence of toxic organic hydrocarbons.
The cis–trans-isomerase (Cti) is a constitutively expressed periplasmic enzyme that – to exert its action – necessitates neither ATP nor other cofactors, and consistently, is independent of de novo synthesis of lipids. A heme-binding site typical of cytochrome c-type proteins is present in the predicted Cti polypeptide indicating a reaction mechanism that renounces temporary saturation of the double bond. Due to its direct correlation with toxicity, cis–trans-isomerization is a potential biomarker for recording solvent stress or changes of other environmental conditions.
- Heipieper HJ, de Waard P, van der Meer P, Killian JA, Isken S, de Bont JAM, Eggink G, de Wolf FA (2001) Regiospecific effect of 1-octanol on cis-trans isomerization of unsaturated fatty acids in the solvent-tolerant strain Pseudomonas putida S12. Appl Microbiol Biotechnol 57:541–547CrossRefPubMedGoogle Scholar
- MacDonald PM, Sykes BD, McElhaney RN (1985) Flourine-19 nuclear magnetic resonance studies of lipid fatty acyl chain order and dynamics in Acholeplasma laidlawii b membranes: a direct comparsion of the effects of cis and trans cyclopropane ring and double-bond substituents on orientational order. Biochemistry 24:4651–4659CrossRefPubMedGoogle Scholar
- Neumann G, Kabelitz N, Zehnsdorf A, Miltner A, Lippold H, Meyer D, Schmid A, Heipieper HJ (2005) Prediction of the adaptability of Pseudomonas putida DOT-T1E to a second phase of a solvent for economically sound two-phase biotransformations. Appl Environ Microbiol 71:6606–6612CrossRefPubMedPubMedCentralGoogle Scholar
- Okuyama H, Okajima N, Sasaki S, Higashi S, Murata N (1991) The cis/trans isomerization of the double bond of a fatty acid as a strategy for adaptation to changes in ambient temperature in the psychrophilic bacterium, Vibrio sp. strain ABE-1. Biochim Biophys Acta 1084:13–20CrossRefPubMedGoogle Scholar