title: Absence of pantothenic acid in gramicidin S synthetase 2 obtained from some mutants of Bacillus brevis.
abstract: The pantothenic acid content of gramicidin S synthetase 2(GS 2) was estimated microbiologically with enzymes obtained from the wild strain and gramicidin S-lacking mutant strains of Bacillus brevis. Four mutant enzymes from BI-4, C-3, E-1, and E-2 lacked pantothenic acid. Other mutant enzymes from BII-3, BI-3, BI-9, and BI-2 contained the same amount of pantothenic acid as the wild-type enzyme. Pantothenic acid-lacking GS 2 belonged to group V of mutant enzymes, which could activate all amino acids related to gramicidin S; their complementary enzyme, gramicidin S synthetase 1(GS 1), lacked racemizing activity. To ascertain whether 4'-phosphopantetheine is involved in the formation of D-phenylalanyl-L-prolyl diketopiperazine (DKP) and gramicidin S, combinations were tested of intact GS 1 from the wild strain with various mutant GS 2 either containing or lacking pantothenic acid. Only the combinations of wild-type GS 1 with mutant GS 2 containing pantothenic acid could synthesize DKP. Combinations with pantothenic acid-lacking GS 2 also failed to elongate peptide chains. Pantothenic acid-lacking GS 2 could bind the four amino acids which constitute gramicidin S as acyladenylates and thioesters, but the binding abilities were lower than those of the wild-type enzyme and other mutant enzymes containing the pantothenic group.
mesh_terms: D000591:Amino Acid Isomerases / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D001407:Bacillus / Q000201:enzymology* / Q000235:genetics; D001681:Biological Assay; D006096:Gramicidin / Q000096:biosynthesis; D007778:Lactobacillus / Q000502:physiology; D009097:Multienzyme Complexes / Q000378:metabolism*; D009154:Mutation; D010205:Pantothenic Acid / Q000378:metabolism*; D010441:Peptide Chain Elongation, Translational; D010453:Peptide Synthases / Q000378:metabolism*; D010649:Phenylalanine / Q000378:metabolism; D010879:Piperazines / Q000096:biosynthesis
chemical_list: D000596:Amino Acids; D009097:Multienzyme Complexes; D010879:Piperazines; D006096:Gramicidin; D010205:Pantothenic Acid; C032442:phenylalanyl-prolyl diketopiperazine; D010649:Phenylalanine; D000591:Amino Acid Isomerases; C022343:phenylalanine racemase (ATP-hydrolyzing); D010453:Peptide Synthases; C020831:gramicidin-S-synthetase 2