| Structural highlights
Function
[A8C927_ECOLX] Specifically methylates the N(1) position of adenine 1408 in 16S rRNA. Confers resistance to various aminoglycosides, including kanamycin, neomycin, apramycin, ribostamycin and gentamicin. Methylates only fully assembled 30S subunits.[1] [2] [3]
Publication Abstract from PubMed
NpmA, a methyltransferase that confers resistance to aminoglycosides was identified in an Escherichia coli clinical isolate. It belongs to the kanamycin-apramycin methyltransferase (Kam) family and specifically methylates the 16S rRNA at the N1 position of A1408. We determined the structures of apo-NpmA and its complexes with S-adenosylmethionine (AdoMet) and S-adenosylhomocysteine (AdoHcy) at 2.4, 2.7 and 1.68 A, respectively. We generated a number of NpmA variants with alanine substitutions and studied their ability to bind the cofactor, to methylate A1408 in the 30S subunit, and to confer resistance to kanamycin in vivo. Residues D30, W107 and W197 were found to be essential. We have also analyzed the interactions between NpmA and the 30S subunit by footprinting experiments and computational docking. Helices 24, 42 and 44 were found to be the main NpmA-binding site. Both experimental and theoretical analyses suggest that NpmA flips out the target nucleotide A1408 to carry out the methylation. NpmA is plasmid-encoded and can be transferred between pathogenic bacteria; therefore it poses a threat to the successful use of aminoglycosides in clinical practice. The results presented here will assist in the development of specific NpmA inhibitors that could restore the potential of aminoglycoside antibiotics.
Structural basis for the methylation of A1408 in 16S rRNA by a panaminoglycoside resistance methyltransferase NpmA from a clinical isolate and analysis of the NpmA interactions with the 30S ribosomal subunit.,Husain N, Obranic S, Koscinski L, Seetharaman J, Babic F, Bujnicki JM, Maravic-Vlahovicek G, Sivaraman J Nucleic Acids Res. 2010 Nov 9. PMID:21062819[4]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Wachino J, Shibayama K, Kurokawa H, Kimura K, Yamane K, Suzuki S, Shibata N, Ike Y, Arakawa Y. Novel plasmid-mediated 16S rRNA m1A1408 methyltransferase, NpmA, found in a clinically isolated Escherichia coli strain resistant to structurally diverse aminoglycosides. Antimicrob Agents Chemother. 2007 Dec;51(12):4401-9. Epub 2007 Sep 17. PMID:17875999 doi:http://dx.doi.org/10.1128/AAC.00926-07
- ↑ Zelinskaya N, Rankin CR, Macmaster R, Savic M, Conn GL. Expression, purification and crystallization of adenosine 1408 aminoglycoside-resistance rRNA methyltransferases for structural studies. Protein Expr Purif. 2011 Jan;75(1):89-94. doi: 10.1016/j.pep.2010.07.005. Epub, 2010 Jul 25. PMID:20667473 doi:http://dx.doi.org/10.1016/j.pep.2010.07.005
- ↑ Husain N, Obranic S, Koscinski L, Seetharaman J, Babic F, Bujnicki JM, Maravic-Vlahovicek G, Sivaraman J. Structural basis for the methylation of A1408 in 16S rRNA by a panaminoglycoside resistance methyltransferase NpmA from a clinical isolate and analysis of the NpmA interactions with the 30S ribosomal subunit. Nucleic Acids Res. 2010 Nov 9. PMID:21062819 doi:10.1093/nar/gkq1033
- ↑ Husain N, Obranic S, Koscinski L, Seetharaman J, Babic F, Bujnicki JM, Maravic-Vlahovicek G, Sivaraman J. Structural basis for the methylation of A1408 in 16S rRNA by a panaminoglycoside resistance methyltransferase NpmA from a clinical isolate and analysis of the NpmA interactions with the 30S ribosomal subunit. Nucleic Acids Res. 2010 Nov 9. PMID:21062819 doi:10.1093/nar/gkq1033
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