Type-II 3-oxoacyl-CoA thiolase of the nematode Caenorhabditis elegans is located in peroxisomes, highly expressed during larval stages and induced by clofibrate

Maebuchi Motohiro

Togo Summnanuna H.

Yokota Sadaki

Ghenea Simona

Bun-ya Masanori

Kamiryo Tatsuyuki

Kawahara Akira

European Journal of Biochemistry

We examined the expression and localization of type-II 3-oxoacyl-CoA thiolase in the nematode Caenorhabditis elegans. Type-II thiolase acts on 3- oxoacyl-CoA esters with a methyl group at the α carbon, whereas conventional thiolases do not. Mammalian type-II thiolase, which is also termed sterol carrier protein x (SCPx) or SCP2/3-oxoacyl-CoA thiolase, is located in the peroxisomes and involved in phytanic acid degradation and most probably in bile acid synthesis. The nematode enzyme lacks the SCP2 domain, which carries the peroxisomal-targeting signal, but produces bile acids in a cell-free system. Northern and Western blot analyses demonstrated that C. elegans expressed type-II thiolase throughout its life cycle, especially during the larval stages, and that the expression was significantly enhanced by the addition of clofibrate at 5 mM or more to the culture medium. Whole-mount in situ hybridization and immunostaining of L4 larvae revealed that the enzyme was mainly expressed in intestinal cells, which are multifunctional like many of the cell types in C. elegans. Subcellular fractionation and indirect immunoelectron microscopy of the nematode detected the enzyme in the matrix of peroxisomes. These results indicate the fundamental homology between mammalian SCPx and the nematode enzyme regardless of whether the SCP2 part is fused, suggesting their common physiological roles.

type-II 3-oxoacyl-CoA thiolase

SCPx

peroxisomes

clofibrate

caenorhabditis elegans

Biology [ 460 ]

eng

Federation of European Biochemical Societies

Copyright (c) 1999 Federation of European Biochemical Societies

[ISSN] 0014-2956

[NCID] AA00639541

[DOI] 10.1046/j.1432-1327.1999.00655.x

[PMID] 10491098

[DOI] http://dx.doi.org/10.1046/j.1432-1327.1999.00655.x isVersionOf