Purification, Molecular Cloning, and Genomic Organization of Human Brain Long-Chain Acyl-CoA Hydrolase

Abstract

An acyl-CoA hydrolase, referred to as hBACH, was purified from human brain cytosol. The enzyme had a molecular mass of 100 kDa and 43-kDa subunits, and was highly active with long-chain acyl-CoAs, e.g. a maximal velocity of 295 micromol/min/mg and K(m) of 6.4 microM for palmitoyl-CoA. Acyl-CoAs with carbon chain lengths of C(8-18) were also good substrates. In human brain cytosol, 85% of palmitoyl-CoA hydrolase activity was titrated by an anti-BACH antibody, which accounted for over 75% of the enzyme activity found in the brain tissue. The cDNA isolated for hBACH, when expressed in Escherichia coli, directed the expression of palmitoyl-CoA hydrolase activity and a 44-kDa protein immunoreactive to the anti-BACH antibody, which in turn neutralized the hydrolase activity. The hBACH cDNA encoded a 338-amino acid sequence which was 95% identical to that of a rat homolog. The hBACH gene spanned about 130 kb and comprised 9 exons, and was mapped to 1p36.2 on the cytogenetic ideogram. These findings indicate that the long-chain acyl-CoA hydrolase present in the brain is well conserved between man and the rat, suggesting a conserved role for this enzyme in the mammalian brain, and enabling genetic studies on the functional analysis of acyl-CoA hydrolase.

Structural basis for recruitment of tandem hotdog domains in acyl-CoA thioesterase 7 and its role in inflammation

“…long-chain acyl-CoA substrates with fatty acid chains of [8][9][10][11][12][13][14][15][16] carbon atoms (C 8 -C 16 ) (7,13). Acot7 contains a pair of fused thioesterase domains that share Ϸ30% sequence identity, with each thioesterase domain predicted to have the hotdog fold structure with an ␣-helix sausage wrapped by a ␤-sheet bun (14)(15)(16).…”

Alternative exon usage selectively determines both tissue distribution and subcellular localization of the acyl-CoA thioesterase 7 gene products

“…It has been shown that Acot7 isoenzymes account for approximately 80-90% of the acyl-CoA thioesterase activity in brain (13,16). However, mRNA is mainly detected in testis, with lower levels in brain and even lower levels in the other tissues, although protein is highest in brain, followed by testis, lung and lower in the other tissues.…”

“…Previous work has shown that the major isoform of the Acot7 gene expressed in brain and testis is the cytosolic Acot7_v1 (previously known as CTE-II or BACHa) (10,13). In order to characterize the mouse gene encoding the Acot7_v1, searches were carried out in mouse EST databases for different 5' ends of Acot7.…”

“…These enzymes were shown to have a broad substrate specificity, and could hydrolyze acyl-CoAs from C 6 -C 22 -CoA (5,8,12,13). There is a very high sequence similarity between the rat, mouse and human ACOT7 sequences, suggesting an important evolutionary conservation of these genes.…”

“…Brain and testis contain by far the highest ACOT activities, and since 75-90% of the activity in brain is due to ACOT7 (13), ACOT7 was also originally designated brain acyl-CoA hydrolase (BACH) (23). In human brain, ACOT7 is expressed in neurons, e.g pyramidal cells in the cerebral cortex and Purkinje cells in the cerebellum (14).…”