H-protein Of Glycine Cleavage System Research Articles

The Mitochondrion-Like Organelle of Trimastix pyriformis Contains the Complete Glycine Cleavage System

All eukaryotic organisms contain mitochondria or organelles that evolved from the same endosymbiotic event like classical mitochondria. Organisms inhabiting low oxygen environments often contain mitochondrial derivates known as hydrogenosomes, mitosomes or neutrally as mitochondrion-like organelles. The detailed investigation has shown unexpected evolutionary plasticity in the biochemistry and protein composition of these organelles in various protists. We investigated the mitochondrion-like organelle in Trimastix pyriformis, a free-living member of one of the three lineages of anaerobic group Metamonada. Using 454 sequencing we have obtained 7 037 contigs from its transcriptome and on the basis of sequence homology and presence of N-terminal extensions we have selected contigs coding for proteins that putatively function in the organelle. Together with the results of a previous transcriptome survey, the list now consists of 23 proteins – mostly enzymes involved in amino acid metabolism, transporters and maturases of proteins and transporters of metabolites. We have no evidence of the production of ATP in the mitochondrion-like organelle of Trimastix but we have obtained experimental evidence for the presence of enzymes of the glycine cleavage system (GCS), which is part of amino acid metabolism. Using homologous antibody we have shown that H-protein of GCS localizes into vesicles in the cell of Trimastix. When overexpressed in yeast, H- and P-protein of GCS and cpn60 were transported into mitochondrion. In case of H-protein we have demonstrated that the first 16 amino acids are necessary for this transport. Glycine cleavage system is at the moment the only experimentally localized pathway in the mitochondrial derivate of Trimastix pyriformis.

The high-resolution X-ray crystallography of bovine H-protein of glycine cleavage system

The high-resolution X-ray crystallography of bovine H-protein of glycine cleavage system

High-Resolution X-ray Crystallography Studies of the H-Protein of Glycine Cleavage System

High-Resolution X-ray Crystallography Studies of the H-Protein of Glycine Cleavage System

20] Lipoate addition to acyltransferases of α-keto acid dehydrogenase complexes and H-protein of glycine cleavage system

Publisher Summary This chapter presents the method employed for the purification of lipoyltransferase from bovine liver mitochondria using lipoyl-AMP and apoH-protein as donor and acceptor of the lipoyl group, respectively. Two isoforms were separated by chromatography on a hydroxylapatite column. The lipoyltransferase that eluted at about 220 mM phosphate was purified to homogeneity and termed “lipoyltransferase II.” Lipoyltransferase I eluted at about 200 mM phosphate and was partly purified. The molecular masses and optimal pH values of lipoyltransferase I and II were both 40 kDa and pH 7.9, respectively. The Km values for lipoyl-AMP obtained with lipoyltransferase I and II were 13 and 16 μM and for apoH-protein were 0.29 and 0.17 μM, respectively. The Vmax values of lipoyltransferase I and II were 135 and 144 nmol/min/mg of protein, respectively. Thus, the biochemical properties of both isoforms were similar. The chapter describes the assay methods for and properties of the lipoylation reaction of lipoyl domains of mammalian acyltransferases (E2s) and H-protein, using purified lipoyltransferase I and II.