The first 6 residues of the biosurfactant lipopeptidolactone arthrofactin have the D configuration, yet none of the 11 modules of the nonribosomal peptide synthetase assembly line have epimerization domains. We show that the two-module ArfA subunit and the first module of the ArfB subunit, which act in tandem to produce the N-acyl-D-Leu1-D-Asp2-D-Thr3-S-protein intermediate, activate the L amin...

Syringomycin, a lipopeptidolactone assembled from nine amino acid monomers by four enzymes, SyrB1, SyrB2, SyrC, and SyrE, is a cyclic nonribosomal peptide made by plant-associated Pseudomonas spp. This assembly is unusual because the terminal residue, 4-chlorothreonine, has been proposed to be added in trans since the ninth module of the megasynthetase SyrE lacks an adenylation domain required ...

A synthetic random polymer of threonine and glutamate (1:4.4) is readily phosphorylated by protein kinase P but not by five other protein-serine (threonine) kinases. A synthetic random polymer of serine and arginine (1:3) is readily phosphorylated by protein kinase A and protein kinase C but not by protein kinase P. Although the amino acid sequences surrounding the phosphorylated serine (threon...