in the rluC- strain, susceptibility to some antibiotics increases dramatically. The most pronounced effects in comparison with the rluC+ control are observed with clindamycin (16-fold), linezolid (8-fold), and tiamulin (4-fold)
deletion of this gene and thus the absence of these three pseudouridine residues has no detectable effect on the exponential growth rate in either rich or minimal glucose medium at temperatures ranging from 24°C to 42°C
excessive pseudouridylation of 23S rRNA by the chimeric mutant RluCD reduces progression of ribosome assembly during early or middle stages. Modification of sites in 23S rRNA prevents ribosome assembly, interfering positions are located inside the ribosome, mapping. It is plausible that pseudouridines can cause RNA misfolding when present at non-native positions. Recombinant expression of RluCD protein itself inhibits ribosome assembly by binding to the precursor particles and blocking the assembly of r-proteins. The phenotypic effects are caused by the catalytic activity of the chimeric pseudouridine synthase RluCD, mechanism, overview. The excessive pseudouridines in rRNA species cause strong selection against 70S ribosome pool. Ribosome assembly defect causes degradation of unassembled rRNA and accumulation of small RNA fragments on the top of gradient
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a proteolytically derived fragment of the enzyme consisting of residues 89-319 retains catalytic activity. Crystals of this fragment, grown by precipitation with sodium acetate at pH 8.0, belong to space group P321, with unit-cell dimensions a = b = 97.1, c = 86.3 A and have two molecules in the crystallographic asymmetric unit. Crystals diffract X-rays to at least 2.3 A resolution and appear suitable for crystal structure determination
construction of a chimeric pseudouridine synthase (RluCD) containing the N-terminal S4 domain of enzyme RluC (EC 220.127.116.11) and the C-terminal catalytic domain of enzyme RluD (EC 18.104.22.168). The chimeric mutant is able to introduce excessive pseudouridines into rRNA at non-native positions. The chimeric enzyme RluCD is used as a tool to study an effect of over-modification of rRNA on the ribosome biogenesis. Excessive pseudouridylation of 23S rRNA reduces progression of ribosome assembly during early or middle stages. A modification interference approach identifies the sites in 23S rRNA whose modification prevents ribosome assembly. It is plausible that pseudouridines can cause RNA misfolding when present at non-native positions. RluCD isomerizes many uridines of rRNA in a non-specific manner. Induction of the RluCD at the exponential growth phase leads to severe inhibition of translation while transcription is only slightly affected
recombinant expression of chimeric enzyme mutants RluCD in Escherichia coli strains M15 and CD204, expression of chimeric pseudouridine synthase RluCD, under control of arabinose inducible araBAD promoter, interferes with ribosome formation in wild-type M15 strain and strain CD204 lacking RluC and RluD, while cells transformed with catalytically inactive RluCD (RluCD D139N) and empty vector (pQE60), used as a controls, represent a normal ribosomal profile in sucrose density gradient. Strain CD204 contains a mutant form of RF-2 (D131Y) that suppresses ribosome assembly defect caused by the deletion of the RluD. Strain rluD114 where yfiI (RluD) gene has been disrupted with Km cassette is used as a parent strain to construct strain CD204