TAILIEUCHUNG - Báo cáo khoa học: Substrate specificity of the pseudouridine synthase RluD in Escherichia coli

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 inEscherichia coli. | ỊFEBS Journal Substrate specificity of the pseudouridine synthase RluD in Escherichia coli Margus Leppik Lauri Peil Kalle Kipper Aivar Liiv and Jaanus Remme Institute of Molecular and Cell Biology Tartu University Tartu Estonia Keywords 23S rRNA helix 69 pseudouridine ribosome assembly RluD Correspondence J. Remme Riia 23 51010 Tartu Estonia Fax 372 42 0286 Tel 372 73 75031 E-mail jremme@ Received 24 May 2007 revised 6 September 2007 accepted 10 September 2007 doi 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. We have analyzed substrate specificity of RluD in vivo. Mutational analyses have revealed a RluD isomerizes uridine in vivo only at positions 1911 1915 and 1917 regardless of the presence of uridine at other positions in the loop of helix 69 of 23S rRNA variants b substitution of one U by C has no effect on the conversion of others . formation of pseudouridines at positions 1911 1915 and 1917 are independent of each other c A1916 is the only position in the loop of helix 69 where mutations affect the RluD specific pseudouridine formation. Pseudouridines were determined in the ribosomal particles from a ribosomal large subunit defective strain RNA helicase DeaD- . An absence of pseudouridines in the assembly precursor particles suggests that RluD directed isomerization of uridines occurs as a late step during the assembly of the large ribosomal subunit. Pseudouridines Y are the most common modifications in stable RNAs. Pseudouridine was discovered as a fifth nucleotide in yeast tRNA 50 years ago 1 . Pseudouridines are synthesized from uridine by pseudouridine synthases a reaction that does not need additional cofactors or external energy sources. Pseudouridine synthases are .

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