5.4.99.24 malfunction an rluC- mutant shows some cold sensitivity 5.4.99.24 malfunction 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 5.4.99.24 malfunction disruption of yceC does not affect the growth 5.4.99.24 malfunction 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) 5.4.99.24 malfunction 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