When this cardiolipin-null strain sporulated, MurG-YFP distri-bution was far less prominent at the forespore than in wild type cells, as shown by a spore/mother cell fluorescence ratio of 1.60 _ .20 (Fig. 4A and B). As a control we monitored FtsW-YFP localization in sporulating wild type cells (JDB2171) and find no difference from a cardiolipin-null background (JDB2285) (Fig. S4). Also, SpoVM localization was not affected in a DclsA background (Fig. S3B). These results show that cardiolipin is necessary and specific for MurG localization to the spore