Acyl-coenzyme A thioesterase 11 also known as StAR-related lipid transfer protein 14 (STARD14) is an enzyme that in humans is encoded by the ACOT11gene.[1][2][3][4] This gene encodes a protein with acyl-CoA thioesterase activity towards medium (C12) and long-chain (C18) fatty acyl-CoA substrates which relies on its StAR-related lipid transfer domain. Expression of a similar murine protein in brown adipose tissue is induced by cold exposure and repressed by warmth. Expression of the mouse protein has been associated with obesity, with higher expression found in obesity-resistant mice compared with obesity-prone mice. Alternative splicing results in two transcript variants encoding different isoforms.[4]
The ACOT11 gene is located on the 1st chromosome, with its specific localization being 1p32.3. It contains 18 exons.[4]
The protein encoded by this gene contains 258 amino acids, and forms a homodimer with another chain. Its theoretical weight is 26.67 kDa.[5] The protein contains a StAR-related transfer domain, which is a domain responsible for binding to lipids. There are 4 known ligands that bind to this homodimer: polyethylene glycol, chlorine, glycerol, and a form of TCEP.[6]
Function
The protein encoded by the ACOT11 gene is part of a family of Acyl-CoAthioesterases, which catalyze the hydrolysis of various Coenzyme A esters of various molecules to the free acid plus CoA. These enzymes have also been referred to in the literature as acyl-CoA hydrolases, acyl-CoA thioester hydrolases, and palmitoyl-CoA hydrolases. The reaction carried out by these enzymes is as follows:
CoA ester + H2O → free acid + coenzyme A
These enzymes use the same substrates as long-chain acyl-CoA synthetases, but have a unique purpose in that they generate the free acid and CoA, as opposed to long-chain acyl-CoA synthetases, which ligate fatty acids to CoA, to produce the CoA ester.[7] The role of the ACOT- family of enzymes is not well understood; however, it has been suggested that they play a crucial role in regulating the intracellular levels of CoA esters, Coenzyme A, and free fatty acids. Recent studies have shown that Acyl-CoA esters have many more functions than simply an energy source. These functions include allosteric regulation of enzymes such as acetyl-CoA carboxylase,[8]hexokinase IV,[9] and the citrate condensing enzyme. Long-chain acyl-CoAs also regulate opening of ATP-sensitive potassium channels and activation of Calcium ATPases, thereby regulating insulin secretion.[10] A number of other cellular events are also mediated via acyl-CoAs, for example signal transduction through protein kinase C, inhibition of retinoic acid-induced apoptosis, and involvement in budding and fusion of the endomembrane system.[11][12][13] Acyl-CoAs also mediate protein targeting to various membranes and regulation of G protein α subunits, because they are substrates for protein acylation.[14] In the mitochondria, acyl-CoA esters are involved in the acylation of mitochondrial NAD+ dependent dehydrogenases; because these enzymes are responsible for amino acid catabolism, this acylation renders the whole process inactive. This mechanism may provide metabolic crosstalk and act to regulate the NADH/NAD+ ratio in order to maintain optimal mitochondrial beta oxidation of fatty acids.[15] The role of CoA esters in lipid metabolism and numerous other intracellular processes are well defined, and thus it is hypothesized that ACOT- enzymes play a role in modulating the processes these metabolites are involved in.[16]
↑Hunt MC, Yamada J, Maltais LJ, Wright MW, Podesta EJ, Alexson SE (Sep 2005). "A revised nomenclature for mammalian acyl-CoA thioesterases/hydrolases". Journal of Lipid Research. 46 (9): 2029–32. doi:10.1194/jlr.E500003-JLR200. PMID16103133.
↑Hunt MC, Rautanen A, Westin MA, Svensson LT, Alexson SE (Sep 2006). "Analysis of the mouse and human acyl-CoA thioesterase (ACOT) gene clusters shows that convergent, functional evolution results in a reduced number of human peroxisomal ACOTs". FASEB Journal. 20 (11): 1855–64. doi:10.1096/fj.06-6042com. PMID16940157.
↑Mashek DG, Bornfeldt KE, Coleman RA, Berger J, Bernlohr DA, Black P, DiRusso CC, Farber SA, Guo W, Hashimoto N, Khodiyar V, Kuypers FA, Maltais LJ, Nebert DW, Renieri A, Schaffer JE, Stahl A, Watkins PA, Vasiliou V, Yamamoto TT (Oct 2004). "Revised nomenclature for the mammalian long-chain acyl-CoA synthetase gene family". Journal of Lipid Research. 45 (10): 1958–61. doi:10.1194/jlr.E400002-JLR200. PMID15292367.
↑Ogiwara H, Tanabe T, Nikawa J, Numa S (Aug 1978). "Inhibition of rat-liver acetyl-coenzyme-A carboxylase by palmitoyl-coenzyme A. Formation of equimolar enzyme-inhibitor complex". European Journal of Biochemistry / FEBS. 89 (1): 33–41. doi:10.1111/j.1432-1033.1978.tb20893.x. PMID29756.
↑Srere PA (Dec 1965). "Palmityl-coenzyme A inhibition of the citrate-condensing enzyme". Biochimica et Biophysica Acta. 106 (3): 445–55. doi:10.1016/0005-2760(65)90061-5. PMID5881327.
↑Gribble FM, Proks P, Corkey BE, Ashcroft FM (Oct 1998). "Mechanism of cloned ATP-sensitive potassium channel activation by oleoyl-CoA". The Journal of Biological Chemistry. 273 (41): 26383–7. doi:10.1074/jbc.273.41.26383. PMID9756869.
↑Nishizuka Y (Apr 1995). "Protein kinase C and lipid signaling for sustained cellular responses". FASEB Journal. 9 (7): 484–96. PMID7737456.
↑Glick BS, Rothman JE (Mar 1987). "Possible role for fatty acyl-coenzyme A in intracellular protein transport". Nature. 326 (6110): 309–12. doi:10.1038/326309a0. PMID3821906.
↑Wan YJ, Cai Y, Cowan C, Magee TR (Jun 2000). "Fatty acyl-CoAs inhibit retinoic acid-induced apoptosis in Hep3B cells". Cancer Letters. 154 (1): 19–27. doi:10.1016/s0304-3835(00)00341-4. PMID10799735.
↑Duncan JA, Gilman AG (Jun 1998). "A cytoplasmic acyl-protein thioesterase that removes palmitate from G protein alpha subunits and p21(RAS)". The Journal of Biological Chemistry. 273 (25): 15830–7. doi:10.1074/jbc.273.25.15830. PMID9624183.
↑Berthiaume L, Deichaite I, Peseckis S, Resh MD (Mar 1994). "Regulation of enzymatic activity by active site fatty acylation. A new role for long chain fatty acid acylation of proteins". The Journal of Biological Chemistry. 269 (9): 6498–505. PMID8120000.
↑Hunt MC, Alexson SE (Mar 2002). "The role Acyl-CoA thioesterases play in mediating intracellular lipid metabolism". Progress in Lipid Research. 41 (2): 99–130. doi:10.1016/s0163-7827(01)00017-0. PMID11755680.
Maruyama K, Sugano S (Jan 1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides". Gene. 138 (1–2): 171–4. doi:10.1016/0378-1119(94)90802-8. PMID8125298.
Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, Suyama A, Sugano S (Oct 1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library". Gene. 200 (1–2): 149–56. doi:10.1016/S0378-1119(97)00411-3. PMID9373149.
Ishikawa K, Nagase T, Suyama M, Miyajima N, Tanaka A, Kotani H, Nomura N, Ohara O (Jun 1998). "Prediction of the coding sequences of unidentified human genes. X. The complete sequences of 100 new cDNA clones from brain which can code for large proteins in vitro". DNA Research. 5 (3): 169–76. doi:10.1093/dnares/5.3.169. PMID9734811.