(p)ppGpp analysis of Pseudomonas sp. strain DF41 and its SR derivatives after serine hydroxamate induction. Cells were labeled with 32P, and nucleotides were extracted and separated by thin-layer chromatography. (A) Lane 1, Pseudomonas aeruginosa strain PAO1; lane 2, Pseudomonas sp. DF41; lane 3, DF41 relA mutant; lane 4, DF41 relA spoT mutant; lane 5, DF41 relA(pUCPrelA) mutant; lane 6, DF41 relA spoT(pUCPrelA) mutant. (B) Lane 1, DF41; lane 2, DF41-469 (gacS mutant); lane 3, DF41-469(pUCP23-gacS); lane 4, DF41-469(pUCPrelA); lane 5, PAO1.