2. |
- Wang, Kai Tuo, et al.
(författare)
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Purification, crystallization and preliminary X-ray crystallographic analysis of 23S RNA m(2)G2445 methyltransferase RlmL from Escherichia coli
- 2010
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Ingår i: Acta Crystallographica. Section F: Structural Biology and Crystallization Communications. - 2053-230X. ; 66:Pt 11, s. 6-1484
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Tidskriftsartikel (refereegranskat)abstract
- The RlmL (YcbY) protein in Escherichia coli is an rRNA methyltransferase that is specific for m(2)G2445 modification of 23S RNA. The rlmL gene was cloned into the expression vector pET28a and expressed in the host E. coli strain BL21 (DE3). Recombinant protein with a six-histidine tag was purified by Ni(2+)-affinity chromatography followed by gel filtration. Crystals were grown using the hanging-drop vapour-diffusion method and a detergent was used as an additive to improve diffraction quality. The final crystals diffracted to 2.2 Å resolution. The crystals belonged to space group P2(1), with unit-cell parameters a = 73.6, b = 140.8, c = 102.9 Å, β = 102.3°. The crystal has a most probable solvent content of 62.8% with two molecules in the asymmetric unit.
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3. |
- Wang, Kai-Tuo, et al.
(författare)
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Structure of the bifunctional methyltransferase YcbY (RlmKL) that adds the m7G2069 and m2G2445 modifications in Escherichia coli 23S rRNA
- 2012
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Ingår i: Nucleic Acids Research. - : Oxford University Press (OUP). - 1362-4962 .- 0305-1048. ; 40:11, s. 48-5138
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Tidskriftsartikel (refereegranskat)abstract
- The 23S rRNA nucleotide m(2)G2445 is highly conserved in bacteria, and in Escherichia coli this modification is added by the enzyme YcbY. With lengths of around 700 amino acids, YcbY orthologs are the largest rRNA methyltransferases identified in Gram-negative bacteria, and they appear to be fusions from two separate proteins found in Gram-positives. The crystal structures described here show that both the N- and C-terminal halves of E. coli YcbY have a methyltransferase active site and their folding patterns respectively resemble the Streptococcus mutans proteins Smu472 and Smu776. Mass spectrometric analyses of 23S rRNAs showed that the N-terminal region of YcbY and Smu472 are functionally equivalent and add the m(2)G2445 modification, while the C-terminal region of YcbY is responsible for the m(7)G2069 methylation on the opposite side of the same helix (H74). Smu776 does not target G2069, and this nucleotide remains unmodified in Gram-positive rRNAs. The E.coli YcbY enzyme is the first example of a methyltransferase catalyzing two mechanistically different types of RNA modification, and has been renamed as the Ribosomal large subunit methyltransferase, RlmKL. Our structural and functional data provide insights into how this bifunctional enzyme evolved.
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