The Products of the spoVA Operon Are Involved in Dipicolinic Acid Uptake into Developing Spores of Bacillus subtilis

Bacillus subtilis cells with mutations in the spoVA operon do not complete sporulation. However, a spoVA strain with mutations that remove all three of the spore's functional nutrient germinant receptors (termed the ger3 mutations) or the cortex lytic enzyme SleB (but not CwlJ) did complete sporulation. ger3 spoVA and sleB spoVA spores lack dipicolinic acid (DPA) and have lower core wet densities and levels of wet heat resistance than wild-type or ger3 spores. These properties of ger3 spoVA and sleB spoVA spores are identical to those of ger3 spoVF and sleB spoVF spores that lack DPA due to deletion of the spoVF operon coding for DPA synthetase. Sporulation in the presence of exogenous DPA restored DPA levels in ger3 spoVF spores to 53% of the wild-type spore levels, but there was no incorporation of exogenous DPA into ger3 spoVA spores. These data indicate that one or more products of the spoVA operon are involved in DPA transport into the developing forespore during sporulation.