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Characterization of Pseudomonas aeruginosa?LpxT reveals dual positional lipid A kinase activity and co-ordinated control of outer membrane modification.

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 Escherichia coli and Salmonella 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.

SUBMITTER: Nowicki EM

PROVIDER: S-EPMC4213358 | biostudies-literature | 2014 Nov

REPOSITORIES: biostudies-literature

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Characterization of Pseudomonas aeruginosa?LpxT reveals dual positional lipid A kinase activity and co-ordinated control of outer membrane modification.

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