TY - JOUR
T1 - Characterization of an arachidonic acid-selective acyl-CoA synthetase from murine T lymphocytes
AU - Taylor, Alan S.
AU - Sprecher, Howard
AU - Russell, John H.
N1 - Funding Information:
The authors thank Aubrey Morrison, Philip Needleman, Angela Wyche and Rawleigh C. Howe for their individual contributions to this work. This work was supported by grant number CA34817 awarded by the National Cancer Institute, DHHS. Some materials were supplied by the Washington University Basic Cancer Research Center which is supported in part by program project grant AI15383 awarded by DHHS. A.C.T. is partially supported by Training grant No. HL07275, DHHS. J.H.R. is the recipient of Research Career Development Award No. CA00926 awarded by the National Cancer Institute, DHHS.
PY - 1985/2/8
Y1 - 1985/2/8
N2 - Evidence is presented that the murine thymoma EL4 and cytotoxic T lymphocyte clones possess two distinct long-chain fatty acyl-CoA synthetase activities. One enzyme shows activity toward a broad spectrum of fatty acid substrates, similar to the long-chain fatty acyl-CoA synthetase from rat liver. The other enzyme is selective for arachidonic acid and related fatty acids. Fatty acid competetion studies using EL4 microsomes demonstrate that [14C]palmitoyl-CoA synthesis (Km = 13 ± 1 μM, Vmax = 7 ± 1 nmol/mg per min) is inhibited by unlabeled palmitate, oleate, linoleate or linolenate (Ki = 15-25 μM) and weakly by arachidonate (Ki > 100 μM). Similar inhibition is observed for the activation of [14C]oleate (Km = 31 ± 3 μM, Vmax = 6 ± 2 nmol/mg per min). On the other hand, [14C]arachidonyl-CoA synthetase (Km = 15 ± 3 μM, Vmax = 13 ± 2 nmol/mg per min) is inhibited by unlabeled arachidonic acid (ki = 20 μM) but not by unlabeled palmitate, oleate, linoleate and linolenate. The description of arachidonoyl-CoA synthetase in cytotoxic T lymphocyte clones represents the first example of a cell with little or no capacity to synthesize arachidonic acid metabolites, yet which possesses a selective esterification mechanism for the fatty acid. Studies on the specificity of the arachidonic acid-selective acyl-CoA synthetase utilized arachidonic acid metabolites and structurally related fatty acids and yielded two points of interest: (1) metabolism of arachidonic acid to monohydroxy fatty acids (HETEs) resulted in compounds with significantly decreased ability to be activated by the arachidonate-selective acyl-CoA synthetase; (2) arachidonate was a much better substrate than was 5,8,11-eicosatrienoic acid (Km = 41 μM), the fatty acid which accumulates during essential fatty acid deficiency. The possible role of an arachidonic acid-selective acyl-CoA synthetase in lymphocyte activation and as a homeostatic mechanism during essential fatty acid deficiency is discussed.
AB - Evidence is presented that the murine thymoma EL4 and cytotoxic T lymphocyte clones possess two distinct long-chain fatty acyl-CoA synthetase activities. One enzyme shows activity toward a broad spectrum of fatty acid substrates, similar to the long-chain fatty acyl-CoA synthetase from rat liver. The other enzyme is selective for arachidonic acid and related fatty acids. Fatty acid competetion studies using EL4 microsomes demonstrate that [14C]palmitoyl-CoA synthesis (Km = 13 ± 1 μM, Vmax = 7 ± 1 nmol/mg per min) is inhibited by unlabeled palmitate, oleate, linoleate or linolenate (Ki = 15-25 μM) and weakly by arachidonate (Ki > 100 μM). Similar inhibition is observed for the activation of [14C]oleate (Km = 31 ± 3 μM, Vmax = 6 ± 2 nmol/mg per min). On the other hand, [14C]arachidonyl-CoA synthetase (Km = 15 ± 3 μM, Vmax = 13 ± 2 nmol/mg per min) is inhibited by unlabeled arachidonic acid (ki = 20 μM) but not by unlabeled palmitate, oleate, linoleate and linolenate. The description of arachidonoyl-CoA synthetase in cytotoxic T lymphocyte clones represents the first example of a cell with little or no capacity to synthesize arachidonic acid metabolites, yet which possesses a selective esterification mechanism for the fatty acid. Studies on the specificity of the arachidonic acid-selective acyl-CoA synthetase utilized arachidonic acid metabolites and structurally related fatty acids and yielded two points of interest: (1) metabolism of arachidonic acid to monohydroxy fatty acids (HETEs) resulted in compounds with significantly decreased ability to be activated by the arachidonate-selective acyl-CoA synthetase; (2) arachidonate was a much better substrate than was 5,8,11-eicosatrienoic acid (Km = 41 μM), the fatty acid which accumulates during essential fatty acid deficiency. The possible role of an arachidonic acid-selective acyl-CoA synthetase in lymphocyte activation and as a homeostatic mechanism during essential fatty acid deficiency is discussed.
KW - Acyl-CoA synthetase
KW - Arachidonate
KW - Essential fatty acid deficiency
KW - Lymphocyte activation
UR - http://www.scopus.com/inward/record.url?scp=0021999302&partnerID=8YFLogxK
U2 - 10.1016/0005-2760(85)90195-X
DO - 10.1016/0005-2760(85)90195-X
M3 - Article
C2 - 3918571
AN - SCOPUS:0021999302
SN - 0005-2760
VL - 833
SP - 229
EP - 238
JO - Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
JF - Biochimica et Biophysica Acta (BBA)/Lipids and Lipid Metabolism
IS - 2
ER -