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Alpha and beta subunits of pyruvate dehydrogenase E1 from the microsporidian Nosema locustae: mitochondrion-derived carbon metabolism in microsporidia.

Abstract：

:Microsporidia are highly adapted eukaryotic intracellular parasites that infect a variety of animals. Microsporidia contain no recognisable mitochondrion, but recently have been shown to have evolved from fungi and to possess heat shock protein genes derived from mitochondria. These findings make it clear that microsporidian ancestors were mitochondrial, yet it remains unknown whether they still contain the organelle, and if so what its role in microsporidian metabolism might be. Here we have characterised genes encoding the alpha and beta subunits of pyruvate dehydrogenase complex E1 (PDH, EC 1.2.4.1) from the microsporidian Nosema locustae. All other amitochondriate eukaryotes studied to date have lost the PDH complex and replaced it with pyruvate:ferredoxin oxidoreductase (PFOR). Nevertheless, molecular phylogeny shows that these Nosema enzymes are most closely related to mitochondrial PDH from other eukaryotes, demonstrating that elements of mitochondrial metabolism have been retained in microsporidia, and that PDH has not been wholly lost. However, there is still no evidence for a mitochondrion in microsporidia, and neither PDH subunit is predicted to encode an amino terminal leader sequence that could function as a mitochondrion-targeting transit peptide, raising questions as to whether these proteins function in a relic organelle or in the cytosol. Moreover, it is also unclear whether these proteins remain part of the PDH complex, or whether they have been retained for another purpose. We propose that microsporidia may utilise a unique pyruvate decarboxylation pathway involving PDH, demonstrating once again the diversity of core metabolism in amitochondriate eukaryotes.

journal_name

Mol Biochem Parasitol

journal_title

Molecular and biochemical parasitology

authors

Fast NM,Keeling PJ

doi

10.1016/s0166-6851(01)00356-5

subject

Has Abstract

pub_date

2001-10-01 00:00:00

pages

201-9

issue

eissn

0166-6851

issn

1872-9428

pii

S0166685101003565

journal_volume

117

pub_type

杂志文章

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Alpha and beta subunits of pyruvate dehydrogenase E1 from the microsporidian Nosema locustae: mitochondrion-derived carbon metabolism in microsporidia.