Bodnar A G, Rachubinski R A
Department of Biochemistry, McMaster University, Hamilton, Ontario, Canada.
Gene. 1990 Jul 16;91(2):193-9. doi: 10.1016/0378-1119(90)90088-9.
3-Ketoacyl-coenzyme A thiolase (thiolase) catalyzes the final step of the fatty acid beta-oxidation pathway in peroxisomes. Thiolase is unique among rat liver peroxisomal enzymes in that it is synthesized as a precursor possessing a 26-amino acid (aa) N-terminal extension which is cleaved to generate the mature enzyme. To facilitate further examination of the synthesis, intracellular transport and processing of this enzyme, cDNA clones were selected from a lambda gt11 rat liver library using antiserum raised against peroxisomal thiolase. Upon sequencing several cDNA clones, it was revealed that there are at least two distinct thiolase enzymes localized to rat liver peroxisomes, one identical to the previously published rat liver peroxisomal thiolase (thiolase 1) [Hijikata et al., J. Biol. Chem. 262 (1987) 8151-8158] and a novel thiolase (thiolase 2). The THL2 cDNA possesses a single open reading frame of 1302 nucleotides (nt) encoding a protein of 434 aa (Mr 44790). The coding region of THL2 cDNA exhibits 94.6% nt sequence identity with THL1 and 95.4% identity at the level of aa sequence. Northern-blot analysis indicates that the mRNA encoding thiolase 2 is approx. 1.7 kb in size. The mRNA encoding thiolase 2 is induced approx. twofold upon treatment of rats with the peroxisome-proliferating drug, clofibrate. In contrast, the thiolase 1 mRNA is induced more than tenfold under similar conditions.
3-酮脂酰辅酶A硫解酶（硫解酶）催化过氧化物酶体中脂肪酸β-氧化途径的最后一步。硫解酶在大鼠肝脏过氧化物酶体酶中是独特的，因为它作为一种前体合成，具有一个26个氨基酸（aa）的N端延伸，该延伸被切割以产生成熟酶。为了便于进一步研究该酶的合成、细胞内运输和加工，使用针对过氧化物酶体硫解酶产生的抗血清从λgt11大鼠肝脏文库中筛选cDNA克隆。对几个cDNA克隆进行测序后发现，大鼠肝脏过氧化物酶体中至少有两种不同的硫解酶，一种与先前发表的大鼠肝脏过氧化物酶体硫解酶（硫解酶1）[Hijikata等人，《生物化学杂志》262（1987）8151-8158]相同，另一种是新型硫解酶（硫解酶2）。THL2 cDNA具有一个1302个核苷酸（nt）的单一开放阅读框，编码一个434个氨基酸（Mr 44790）的蛋白质。THL2 cDNA的编码区在核苷酸序列水平上与THL1具有94.6%的序列同一性，在氨基酸序列水平上具有95.4%的同一性。Northern印迹分析表明，编码硫解酶2的mRNA大小约为1.7 kb。在用过氧化物酶体增殖药物氯贝丁酯处理大鼠后，编码硫解酶2的mRNA诱导约两倍。相比之下，在类似条件下，硫解酶1 mRNA诱导超过十倍。
