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- Title
Characterization of P seudomonas aeruginosa LpxT reveals dual positional lipid A kinase activity and co-ordinated control of outer membrane modification.
- Authors
Nowicki, Emily M.; O'Brien, John P.; Brodbelt, Jennifer S.; Trent, M. Stephen
- Abstract
Gram-negative bacteria have evolved modification machinery to promote a dynamic outer membrane in response to a continually fluctuating environment. The kinase LpxT, for example, adds a phosphate group to the lipid A moiety of some Gram-negatives including E scherichia coli and S almonella enterica. LpxT activity is inhibited under conditions that compromise membrane integrity, resulting instead in the addition of positively charged groups to lipid A that increase membrane stability and provide resistance to cationic antimicrobial peptides. We have now identified a functional lpxT orthologue in P . aeruginosa. LpxTPa has unique enzymatic characteristics, as it is able to phosphorylate P . aeruginosa lipid A at two sites of the molecule. Surprisingly, a previously uncharacterized lipid A 4′-dephospho-1-triphosphate species was detected. LpxTPa activity is inhibited by magnesium independently of lpxTPa transcription. Modulation of LpxTPa activity is influenced by transcription of the lipid A aminoarabinose transferase ArnT, known to be activated in response to limiting magnesium. These results demonstrate a divergent activity of LpxTPa, and suggest the existence of a co-ordinated regulatory mechanism that permits adaptation to a changing environment.
- Subjects
BACTERIAL lipids; BACTERIAL cell walls; PROTEIN kinases; PEPTIDE antibiotics; MOLECULAR microbiology
- Publication
Molecular Microbiology, 2014, Vol 94, Issue 3, p728
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/mmi.12796