FIG. 2.
Effect of a nonpolar spoIIIJ mutation on the expression of spoIIIG-lacZ and immunoblot analysis of σG accumulation in the spoIIIJ mutant. (A) Expression of a spoIIIG-lacZ fusion was monitored at the indicated times after the onset of sporulation in the spoIIIJ mutant, JOB44 (circles) or in the wild-type strain, MB24 (squares). Endogeneous levels of β-galactosidase activity were determined in the wild-type strain MB24 (triangles). Enzyme activity was measured in Miller units. T0 indicates the end of the exponential phase of growth, defined as the onset of sporulation. (B and C) Immunoblot analysis of σG accumulation in DSM in the wild-type strain MB24 (B) or in the spoIIIJ::km mutant JOB44 (C). Samples from sporulating cultures were collected at the onset of sporulation in DSM (lanes 0) and at hourly intervals thereafter, as indicated. Proteins (30 μg) in each sample were subjected to immunoblot analysis with an anti-σG rabbit polyclonal antibody (see Materials and Methods). Lanes 7, 30 μg of an extract prepared from a culture of a spoIIIG deletion mutant (AH45 [Table 1]) at h 4 of sporulation. The arrowhead indicates the position of σG; other bands represent nonspecific cross-reactive material. The positions of molecular weight (MW) markers are shown on the left.