TABLE 2.

Peptidoglycan incorporation into side walls near poles of E. coli

StrainTreatmenta (protein inhibited)Avg slopeb (arbitrary units/pixel ± SD)No. of measurements
MG1655Aztreonam (PBP 3)4.1 ± 2.412
MG1655SulA (FtsZ)3.8 ± 1.712
AV23-1Aztreonam (PBP 3)3.7 ± 1.513
AV23-1SulA (FtsZ)1.2 ± 0.7c 9
  • a Aztreonam (1 to 2 μg/ml) was added to inhibit the essential septation protein PBP 3 while leaving the function of FtsZ intact. The SulA protein was produced by arabinose induction of the sulA gene on plasmid pFAD38, thereby inhibiting FtsZ.

  • b E. coli sacculi were isolated from strains labeled with d-cysteine and then incubated (chased) in its absence. Peptidoglycan incorporation was quantified by measuring the gray-level profiles of 100 midline pixels along the length of each sacculus, beginning at each pole, moving toward the center of the cell.

  • c The slopes for incorporation of peptidoglycan into E. coli treated with SulA were significantly different (according to Student's t test) between AV23-1 and MG1655 (P < 0.001) and between AV23-1 and AV23-1 treated with aztreonam (P < 0.001).