5.4.99.23: 23S rRNA pseudouridine1911/1915/1917 synthase
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For detailed information about 23S rRNA pseudouridine1911/1915/1917 synthase, go to the full flat file.
Reaction
Synonyms
pseudouridine synthase RluD, pseudouridine synthases RluD, ribosomal large subunit pseudouridine synthase D, RluD, RluD pseudouridine synthase, sfhB, YfiI, YfiL
ECTree
5.4.99.23 23S rRNA pseudouridine1911/1915/1917 synthaseAdvanced search results
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General Information on EC 5.4.99.23 - 23S rRNA pseudouridine1911/1915/1917 synthase
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GENERAL INFORMATION 
ORGANISM
UNIPROT
COMMENTARY 
LITERATURE
evolution
the structure of RluD (a RluA family member) emphasizes that the RluA, RsuA, TruB, and TruA families of pseudouridine synthases arose by divergent evolution from a common ancestor
malfunction
physiological function
malfunction
-
a mutation that suppresses the growth defect of an rluD mutant localizes to prfB, which encodes peptide chain release factor RF2
malfunction
a truncation mutant of the gene for RluD (responsible for synthesis of 23S rRNA pseudouridines 1911, 1915, and 1917) blocks pseudouridine formation and inhibits growth. RluD mutants D139T and D139N are completely inactive in vivo and in vitro. In vivo, the growth defect can be completely restored by transformation of an RluD-inactive strain with plasmids carrying genes for RluD D139T or RluD D139N. Pseudouridine sequencing of the 23S rRNA from these transformed strains demonstrates the lack of these pseudouridines. Pseudoreversion is not responsible because transformation with empty vector under identical conditions does not alter the growth rate
malfunction
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loss of the RluD protein and its product pseudouridine residues (pseudouridine1911, pseudouridine 1915 and pseudouridine 1917) in a deletion strain lacking the rluD gene. This strain exhibits defects in ribosome assembly, biogenesis, and function. Specifically, there is a deficit of 70S ribosomes, an increase in 50S and 30S subunits, and the appearance of new 62S (derived from the breakdown of unstable 70S ribosomes) and 39S particles (immature precursors of the 50S subunits). The defect in ribosome assembly and resulting growth phenotype of the mutant could be restored by expression of wild-type RluD and synthesis of C1911, C1915, and C1917 residues, but not by catalytically inactive mutant RluD proteins, incapable of pseudouridine formation
malfunction
the absence of RluD results in severe growth inhibition. Both the absence of pseudouridine and the growth defect can be reversed by insertion of a plasmid carrying the rluD gene into the mutant cell, clearly linking both effects to the absence of RluD. Growth inhibition may be due to the lack of one or more of the 23S RNA pseudouridines made by this synthase since pseudouridines 1915 and 1917 are universally conserved and are located in proximity to the decoding center of the ribosome where they could be involved in modulating codon recognition
malfunction
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deletion of the rluD gene in Salmonella enterica has negligible effects on growth, ribosomal subunit association, or stop codon readthrough
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
physiological function
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at least one of the three pseudouridine bases appears to have a function in termination of translation
physiological function
-
pseudouridine synthase RluD converts uridines at positions 1911, 1915, and 1917 of 23S rRNA to pseudouridines. These nucleotides are located in the functionally important helix-loop 69 of 23S rRNA. RluD is the only pseudouridine synthase that is required for normal growth in Escherichia coli. RluD directed isomerization of uridines occurs as a late step during the assembly of the (50S) large ribosomal subunit
physiological function
RluD is a ribosomal assembly factor that may be involved in the late stages of maturation of the large ribosomal subunit
