Accumulation of heptaprenyl diphosphate sensitizes Bacillus subtilis to bacitracin: implications for the mechanism of resistance mediated by the BceAB transporter. Issue 1 (23rd May 2014)

• Record Type: Journal Article
• Authors: Kingston, Anthony W.; Zhao, Heng; Cook, Gregory M.; Helmann, John D.
• Is Part Of: Molecular microbiology. Volume 93:Issue 1(2014)
• Page Start: 37
• Page End: 49
• Publication Date: 2014-05-23
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12637
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Heptaprenyl diphosphate (C<sub>35</sub>‐PP) is an isoprenoid intermediate in the synthesis of both menaquinone and the sesquarterpenoids. We demonstrate that inactivation of <italic>ytpB</italic>, encoding a C<sub>35</sub>‐PP utilizing enzyme required for sesquarterpenoid synthesis, leads to an increased sensitivity to bacitracin, an antibiotic that binds undecaprenyl pyrophosphate (C<sub>55</sub>‐PP), a key intermediate in cell wall synthesis. Genetic studies indicate that bacitracin sensitivity is due to accumulation of C<sub>35</sub>‐PP, rather than the absence of sesquarterpenoids. Sensitivity is accentuated in a <italic>ytpB menA</italic> double mutant, lacking both known C<sub>35</sub>‐PP consuming enzymes, and in a <italic>ytpB</italic> strain overexpressing the HepST enzyme that synthesizes C<sub>35</sub>‐PP. Conversely, sensitivity in the <italic>ytpB</italic> background is suppressed by mutation of <italic>hepT</italic> or by supplementation with 1, 4‐dihydroxy‐2‐naphthoate, a co‐substrate with C<sub>35</sub>‐PP for MenA. Bacitracin sensitivity results from impairment of the BceAB and BcrC resistance mechanisms by C<sub>35</sub>‐PP: in a <italic>bceAB bcrC</italic> double mutant disruption of <italic>ytpB</italic> no longer increases bacitracin sensitivity. These results suggest that C<sub>35</sub>‐PP inhibits both BcrC (a C<sub>55</sub>‐PP phosphatase) and BceAB (an ABC transporter that confers bacitracin resistance). These findings lead to a model in which BceAB protects against bacitracin by transfer of the target, C<sub>55</sub>‐PP, rather than the antibiotic across the membrane.</p> </abstract>