Coordinating bacterial cell division with nutrient availability: a role for glycolysis (#15)
Cell division in bacteria is driven by a
cytoskeletal ring structure, the Z ring, composed of polymers of the
tubulin-like protein FtsZ. Z ring formation must be tightly regulated to ensure
faithful cell division, and several mechanisms have been described that
influence the positioning and timing of Z ring assembly. Another important but
as yet poorly understood aspect of cell division regulation is the need to
coordinate division with cell growth and nutrient availability. In this study
we demonstrate for the first time that cell division is intimately linked to
central carbon metabolism in the model Gram positive bacterium Bacillus subtilis. We show that a
deletion of the gene encoding pyruvate kinase (pyk), which produces pyruvate in
the final reaction of glycolysis, rescues the assembly defect of a temperature
sensitive ftsZ mutant and has significant effects on Z ring formation in
wild-type B. subtilis cells. Addition
of exogenous pyruvate restores normal division in the absence of the pyruvate
kinase enzyme, implicating pyruvate as a key metabolite in the coordination of
bacterial growth and division. Our results support a model in which pyruvate
levels are coupled to Z ring assembly via an enzyme that actually metabolizes
pyruvate, the E1 alpha subunit of pyruvate dehydrogenase. We show that this
protein localizes over the nucleoid in a pyruvate-dependent manner, and may
stimulate more efficient Z ring formation at the cell centre under
nutrient-rich conditions when cells must divide more frequently. Ultimately
this helps to ensure the survival of newborn cells.