IMMUNOCHEMICALLY DISTINCT NADP-LINKED ISOCITRATE DEHYDROGENASE ISOZYMES IN MITOCHONDRIA AND PEROXISOMES OF CANDIDA-TROPICALIS

Citation
T. Imajo et al., IMMUNOCHEMICALLY DISTINCT NADP-LINKED ISOCITRATE DEHYDROGENASE ISOZYMES IN MITOCHONDRIA AND PEROXISOMES OF CANDIDA-TROPICALIS, Archives of microbiology, 168(5), 1997, pp. 389-395
Citations number
32
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Microbiology
Journal title
ISSN journal
0302-8933
Volume
168
Issue
5
Year of publication
1997
Pages
389 - 395
Database
ISI
SICI code
0302-8933(1997)168:5<389:IDNIDI>2.0.ZU;2-X
Abstract
Although peroxisomal localization of NADP-linked isocitrate dehydrogen ase (Idp) was first demonstrated in Candida tropicalis, the mitochondr ial isozyme has not been found in this yeast. Here we report that the presence of mitochondrial Idp in the yeast was demonstrated by screeni ng for its gene with a DNA probe containing conserved sequences of Idp s from various organisms. The nucleotide sequence of the gene (CtIDP1) revealed a 1,290-bp open reading frame corresponding to a 430-amino-a cid protein with a high similarity to previously reported Idps, Overex pression of CtIDP1 in Saccharomyces cerevisiae gave a high intracellul ar Idp activity, and the purified recombinant Idp was shown to be a ho modimer with a subunit molecular mass of approximately 44 kDa, differe nt from that of peroxisomal Idp (45 kDa) previously purified from C. t ropicalis. Western blot analysis of the subcellular fractions from ace tate-grown C. tropicalis with polyclonal antibodies raised against the recombinant CtIdp1 showed that the CtIdp1 in C. tropicalis was locali zed in mitochondria but not in peroxisomes, Similar levels of CtIDP1 m RNA and its protein product were detected in cells grown on glucose, a cetate, and n-alkane, although a slight decrease was observed in n-alk ane-grown cells. From these results, CtIdp1 was demonstrated to be mit ochondrial Idp. The properties of mitochondrial Idp and peroxisomal Id p isozymes were proven to be similar, but they were immunochemically d istinct, suggesting the presence of another gene responsible for perox isomal Idp in C. tropicalis.