Characterization of an acyl-CoA thioesterase that functions as a major regulator of peroxisomal lipid metabolism
Characterization of an acyl-CoA thioesterase that functions as a major regulator of peroxisomal lipid metabolism
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DOI：
10.1074/jbc.m106458200
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发表时间：
2002-01-11
影响因子：
4.8
通讯作者：
Alexson, SEH
中科院分区：
文献类型：
--
作者：
Hunt, MC;Solaas, K;Alexson, SEH
过氧化物酶体在超长和长链脂肪酸、二羧酸、胆汁酸中间体、前列腺素、白三烯、血栓烷、磷酸和异种羧酸的β -氧化中起作用。这些脂质主要被链缩短以羧酸形式排出体外，或被转运到线粒体进一步代谢。这些羧酸中的一些被缓慢氧化，因此可能会隔离辅酶A （CoASH）。为了防止CoASH的固存和促进短链羧酸的排泄，催化酰基辅酶a水解为游离酸和CoASH的酰基辅酶a硫酯酶可能发挥重要作用。本文克隆并鉴定了一种小鼠过氧化物酶体酰基辅酶a硫酯酶，命名为PTE-2（过氧化物酶体酰基辅酶a硫酯酶2）。PTE-2通过过氧化物酶体增殖因子wy - 14643和禁食在mRNA水平上无所不在地表达和诱导。这些处理的诱导作用依赖于过氧化物酶体增殖物激活受体。重组PTE-2对短链、中链、长链酰基辅酶a和其他底物（包括三羟基辅酶a、羟甲基戊二酰辅酶a和支链酰基辅酶a）具有宽链长度特异性，这些底物均存在于过氧化物酶体中。以原胆汁酸的CoA酯-胆酰CoA和鹅脱氧胆酰CoA为底物，活性最高。游离CoASH可抑制PTE-2活性，提示胞内游离CoASH水平可调节该酶的活性。重组PTE-2的酰基辅酶a特异性与纯化的小鼠肝脏过氧化物酶体非常相似，表明PTE-2是过氧化物酶体中主要的酰基辅酶a硫酯酶。将重组PTE-2添加到含有分离小鼠肝脏过氧化物酶体的培养液中，可以强烈抑制胆汁酸-辅酶a：氨基酸n -酰基转移酶的活性，表明这种硫酯酶可以干扰coash依赖的途径。我们认为PTE-2是过氧化物酶体脂质代谢的关键调节因子。
Peroxisomes function in beta-oxidation of very long and long-chain fatty acids, dicarboxylic fatty acids, bile acid intermediates, prostaglandins, leukotrienes, thromboxanes, pristanic acid, and xenobiotic carboxylic acids. These lipids are mainly chain-shortened for excretion as the carboxylic acids or transported to mitochondria for further metabolism. Several of these carboxylic acids are slowly oxidized and may therefore sequester coenzyme A (CoASH). To prevent CoASH sequestration and to facilitate excretion of chain-shortened carboxylic acids, acyl-CoA thioesterases, which catalyze the hydrolysis of acyl-CoAs to the free acid and CoASH, may play important roles. Here we have cloned and characterized a peroxisomal acyl-CoA thioesterase from mouse, named PTE-2 (peroxisomal acyl-CoA thioesterase 2). PTE-2 is ubiquitously expressed and induced at mRNA level by treatment with the peroxisome proliferator WY-14,643 and fasting. Induction seen by these treatments was dependent on the peroxisome proliferator-activated receptor alpha. Recombinant PTE-2 showed a broad chain length specificity with acyl-CoAs from short- and medium-, to long-chain acyl-CoAs, and other substrates including trihydroxycoprostanoyl-CoA, hydroxymethylglutaryl-CoA, and branched chain acyl-CoAs, all of which are present in peroxisomes. Highest activities were found with the CoA esters of primary bile acids choloyl-CoA and chenodeoxycholoyl-CoA as substrates. PTE-2 activity is inhibited by free CoASH, suggesting that intraperoxisomal free CoASH levels regulate the activity of this enzyme. The acyl-CoA specificity of recombinant PTE-2 closely resembles that of purified mouse liver peroxisomes, suggesting that PTE-2 is the major acyl-CoA thioesterase in peroxisomes. Addition of recombinant PTE-2 to incubations containing isolated mouse liver peroxisomes strongly inhibited bile acid-CoA:amino acid N-acyltransferase activity, suggesting that this thioesterase can interfere with CoASH-dependent pathways. We propose that PTE-2 functions as a key regulator of peroxisomal lipid metabolism.