To better understand how enzyme localization affects enzyme activity we studied the cellular
localization of the glycosyltransferase MurG, an enzyme necessary for cell wall synthesis at the spore
during sporulation in the bacterium Bacillus subtilis. During sporulation MurG was gradually enriched to
the membrane at the forespore and point mutations in a MurG helical domain disrupting its localization
to the membrane caused severe sporulation defects, but did not affect localization nor caused detectable
defects during exponential growth. We found that this localization is dependent on the phospholipid
cardiolipin, as in strains where the cardiolipin-synthesizing genes were deleted, MurG levels were
diminished at the forespore. Furthermore, in this cardiolipin-less strain, MurG localization during
sporulation was rescued by external addition of purified cardiolipin. These results support localization as
a critical factor in the regulation of proper enzyme function and catalysis.