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Background The KsgA methyltransferase has been conserved throughout evolution, methylating two adenosines in the small subunit rRNA in all three domains of life as well as in eukaryotic organelles that contain ribosomes. Understanding of KsgA’s important role in ribosome biogenesis has been recently expanded in Escherichia coli; these studies help explain why KsgA is so highly conserved and also suggest KsgA’s potential as an antimicrobial drug target.
Results We have analyzed KsgA’s contribution to ribosome biogenesis and cell growth in Staphylococcus aureus. We found that deletion of ksgA in S. aureus led to a cold-sensitive growth phenotype, although KsgA was not as critical for ribosome biogenesis as it was shown to be in E. coli. Additionally, the ksgA knockout strain showed an increased sensitivity to aminoglycoside antibiotics. Overexpression of a catalytically inactive KsgA mutant was deleterious in the knockout strain but not the wild-type strain; this negative phenotype disappeared at low temperature.
Conclusions This work extends the study of KsgA, allowing comparison of this aspect of ribosome biogenesis between a Gram-negative and a Gram-positive organism. Our results in S. aureus are in contrast to results previously described in E. coli, where the catalytically inactive protein showed a negative phenotype in the presence or absence of endogenous KsgA.
© 2012 O'Farrell and Rife; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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VCU Physiology and Biophysics Publications
Growth curves of RN and ΔksgA strains. Data represent experiments performed in triplicate; error bars indicate standard deviation.
1471-2180-12-244-s2.pdf (72 kB)
Growth curves of pCN constructs. Data represent experiments performed in triplicate; error bars indicate standard deviation.
1471-2180-12-244-s3.pdf (29 kB)
Primers used in knockout construction, KsgA cloning, and mutagenesis.
1471-2180-12-244-s4.pdf (31 kB)
Antibiotic resistance of RN4220, ΔksgA, and ΔksgA + pCN51-KsgA strains.
1471-2180-12-244-s5.pdf (24 kB)
Experiments were performed in triplicate; error bars indicate standard deviation.