Thiamine binding

Abstract: A patient who responded to thiamine therapy with reduction of lactate in the blood and cerebrospinal fluid and clinical improvement was studied Cultured lymphoblastoid cells of this patient were found to show reduced activities of pyruvate dehydrogenase complex (PDHC) and pyruvate dehydrogenase, decreased affinity of PDHC for thiamine pyrophosphate, and defective activation of PDHC by pyruvate dehydrogenase phosphatase PDHC deficiency in fibroblasts and biopsied muscle of this patient was also due to the decreased affinity of PDHC for thiamine pyrophosphate A mutation in the E1 alpha subunit containing the thiamine binding site and serine phosphorylation site regulating the activation/inactivation of PDHC was characterized by the polymerase chain reaction and DNA sequencing A single A-->G transition was identified at position 131, resulting in the substitution of Arg-44 for His-44 This mutation must be a de novo mutation because it was not found in either parent's genomic DNA In this study, we have obtained the first evidence at the molecular level for a mutation of thiamine-responsive PDHC deficiency

Abstract: Genes encoding high-affinity folate- and thiamine-binding proteins (FolT, ThiT) were identified in the Lactobacillus casei genome, expressed in Lactococcus lactis, and functionally characterized. Similar genes occur in many Firmicutes, sometimes next to folate or thiamine salvage genes. Most thiT genes are preceded by a thiamine riboswitch.

Abstract: 1-Deoxy-d-xylulose-5-phosphate synthase (DXS) catalyses the first committed step of the 2C-methyl-d-erythritol-4-phosphate (MEP) pathway, which is an alternative isoprenoids biosynthetic route that has been recently discovered In this work, a DXS1-like cDNA (GmDXS1) was isolated from soybean The full-length cDNA of GmDXS1 encoded 708 amino acid residues with a predicted molecular mass of 764 KD Sequence alignment showed that GmDXS1 had high homology to known DXS proteins from other plant species and contained the conserved N-terminal plastid transit peptide, the N-terminal thiamine binding domain and pyridine binding DRAG domain Phylogenetic analysis indicated that GmDXS1 belonged to the plant DXS1 cluster Southern blot analysis indicated that a single copy of GmDXS1 gene existed in soybean genome Tissue expression analysis revealed that GmDXS1 expressed in all photosynthetic tissues except pod walls and roots Green fluorescence analysis with the fusion protein 35S:GmDXS1:GFP suggested that GmDXS1 was localized in plastid The relatively higher photosynthetic pigment content in transgenic tobacco leaves compared to the control implied that GmDXS1 catalyzed the first potential regulatory step in photosynthetic pigment biosynthesis via the MEP pathway