Biochemical characterization of the Mycobacterium tuberculosis phosphoribosyl-1-pyrophosphate synthetase

Mycobacterium tuberculosis arabinogalactan (AG) is an essential cell wall component. It provides a molecular framework serving to connect peptidoglycan to the outer mycolic acid layer. The biosynthesis of the arabinan domains of AG and lipoarabinomannan (LAM), occurs via a combination of membrane bound arabinofuranosyltransferases, all of which utilise decaprenol-1-monophosphorabinose as a substrate (DPA). The source of arabinose ultimately destined for deposition into cell wall AG or LAM, originates exclusively from phosphoribosyl-1-pyrophosphate (pRpp), a central metabolite which is also required for other essential metabolic processes, such as de novo purine and pyrimidne biosynthesis. In M. tuberculosis, a single pRpp synthetase enzyme (Mt-PrsA) is soley responsible for the generation of pRpp, by catalysing the transfer of pyrophosphate from ATP to the C1 hydroxyl position of ribose-5-phosphate. Here, we report a detailed biochemical and biophysical study of Mt-PrsA, which exhibits the most rapid enzyme kinetics reported for a pRpp synthetase

Analysis of amino acid and codon usage in Paramecium bursaria

AbstractThe ciliate Paramecium bursaria harbors the green-alga Chlorella symbionts. We reassembled the P. bursaria transcriptome to minimize falsely fused transcripts, and investigated amino acid and codon usage using the transcriptome data. Surface proteins preferentially use smaller amino acid residues like cysteine. Unusual synonymous codon and amino acid usage in highly expressed genes can reflect a balance between translational selection and other factors. A correlation of gene expression level with synonymous codon or amino acid usage is emphasized in genes down-regulated in symbiont-bearing cells compared to symbiont-free cells. Our results imply that the selection is associated with P. bursaria–Chlorella symbiosis

Insight into cordycepin biosynthesis of Cordyceps militaris : Comparison between a liquid surface culture and a submerged culture through transcriptomic analysis

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Imbalance in Carbon and Nitrogen Metabolism in Comamonas testosteroni R2 Is Caused by Negative Feedback and Rescued by L-arginine

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