Abstract
BackgroundChanges in nutrient availability have dramatic and well-defined impacts on both transcription and translation in bacterial cells. At the same time, the role of post-translational control in adaptation to nutrient-poor environments is poorly understood. Previous studies demonstrate the ability of the glucosyltransferase UgtP to influence cell size in response to nutrient availability. Under nutrient-rich medium, interactions with its substrate UDP-glucose promote interactions between UgtP and the tubulin-like cell division protein FtsZ in Bacillus subtilis, inhibiting maturation of the cytokinetic ring and increasing cell size. In nutrient-poor medium, reductions in UDP-glucose availability favor UgtP oligomerization, sequestering it from FtsZ and allowing division to occur at a smaller cell mass.ResultsIntriguingly, in nutrient-poor conditions UgtP levels are reduced ~ 3-fold independent of UDP-glucose. B. subtilis cells cultured under different nutrient conditions indicate that UgtP accumulation is controlled through a nutrient-dependent post-translational mechanism dependent on the Clp proteases. Notably, all three B. subtilis Clp chaperones appeared able to target UgtP for degradation during growth in nutrient-poor conditions.ConclusionsTogether these findings highlight conditional proteolysis as a mechanism for bacterial adaptation to a rapidly changing nutritional landscape.
Highlights
Changes in nutrient availability have dramatic and well-defined impacts on both transcription and translation in bacterial cells
UgtP accumulation is subject to nutrient-dependent post-translational regulation In our initial investigation, we observed that the intracellular concentration of a UgtP-6XHis fusion protein was three to four-fold lower when cells were cultured under carbon-poor conditions, but unaffected by the absence of UDP-glucose [4]
The net result is a reduction in the UgtP:FtsZ ratio from ~ 1:2 in Lysogeny Broth (LB) to as low as ~ 1:8 in minimal medium based on previous calculations of absolute FtsZ and UgtP concentrations per cell [4, 22]
Summary
Changes in nutrient availability have dramatic and well-defined impacts on both transcription and translation in bacterial cells. The role of post-translational control in adaptation to nutrient-poor environments is poorly understood. Numerous studies have explored how changes in nutrient composition and growth rate impact transcription and translation, which in large part is a response mediated via accumulation of the signaling molecule guanosine pentaphosphate ((p)ppGpp) [6,7,8,9]. Posttranslational regulation has been implicated in adaptation to changes in growth phase (e.g. carbon starvation [10, 11]), how fluctuations in nutritional content and growth rate impact post-translational regulation at the molecular level is poorly defined
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