Human C3d

New RNA modifications are needed to advance our toolbox for targeted manipulation of RNA. In particular, the development of high-performance reporter groups facilitating spectroscopic analysis of RNA structure and dynamics, and of RNA-ligand interactions has attracted considerable interest. To this end, fluorine labeling in conjunction with F-19-NMR spectroscopy has emerged as a powerful strategy. Appropriate probes for RNA previously focused on single fluorine atoms attached to the 5-position of pyrimidine nucleobases or at the ribose 2 '-position. To increase NMR sensitivity, trifluoromethyl labeling approaches have been developed, with the ribose 2 '-SCF3 modification being the most prominent one. A major drawback of the 2 '-SCF3 group, however, is its strong impact on RNA base pairing stability. Interestingly, RNA containing the structurally related 2 '-OCF3 modification has not yet been reported. Therefore, we set out to overcome the synthetic challenges toward 2 '-OCF3 labeled RNA and to investigate the impact of this modification. We present the syntheses of 2 '-OCF3 adenosine and cytidine phosphoramidites and their incorporation into oligoribonucleotides by solid-phase synthesis. Importantly, it turns out that the 2 '-OCF3 group has only a slight destabilizing effect when located in double helical regions which is consistent with the preferential C3 '-endo conformation of the 2 '-OCF3 ribose as reflected in the (3)J (H1 '-H2 ') coupling constants. Furthermore, we demonstrate the exceptionally high sensitivity of the new label in F-19-NMR analysis of RNA structure equilibria and of RNA-small molecule interactions. The study is complemented by a crystal structure at 0.9 angstrom resolution of a 27 nt hairpin RNA containing a single 2 '-OCF3 group that well integrates into the minor groove. The new label carries high potential to outcompete currently applied fluorine labels for nucleic acid NMR spectroscopy because of its significantly advanced performance.

The glomerulonephritis (GN) of granulomatosis polyangiitis is described as "pauci immune" because the glomeruli show little or no evidence of immune complex deposition by immunofluorescence or electron microscopy. Here we describe a severe crescentic GN in which the patient was myeloperoxidase-antineutrophil cytoplasmic antibodies (MPO-ANCA) positive, and on renal biopsy the glomeruli were pauci immune (there were only a few electron-dense deposits). However, by immunofluorescence the glomeruli showed "full-house" staining (the glomeruli stained positive for C1q, C3, IgG, IgA, and IgM). The latter staining pattern would be consistent with that seen in patients with lupus-like GN or with severe crescentic GN as a result of bacterial infection. So, should this patient receive high-dose immunosuppressive therapy and steroid therapy to treat presumed autoimmune GN. or should the patient receive intensive antibiotic therapy to treat a presumed underlying severe infection? This dilemma was soon resolved because the patient's blood culture returned positive for Streptococcus mutans and cardiac echo showed evidence of bacterial endocarditis. This report provides further detail regarding the patient's clinical issues.