Following tyrothricin peptide production by Brevibacillus parabrevis with electrospray mass spectrometry.

摘要: Abstract The tyrocidines and analogues are cationic cyclodecapeptides [cyclo (D-Phe1-L-Pro2-L-(Phe3/Trp3)-D-(Phe4/Trp4)-L-Asn5-L-Gln6-L-(Tyr7/Phe7/Trp7)-L-Val8-L-(Orn9/Lys9)-L-Leu10], produced together with the neutral linear pentadecapeptide gramicidins, in antibiotic tyrothricin complex by Brevibacillus parabrevis. Despite discovery 80 years ago, it was still uncertain whether these peptides secreted or sequestered intracellularly. We resolved this utilising high resolution electrospray mass spectrometry to confirm predominantly intracellular sequestration of complex. A “peptidomics” approach allowed us map production 16 6 gramicidins over days culturing. Gramicidin remained relatively constant, Val-gramicidin predominant analogue throughout day fermentation period. have four variable positions there a culturing time related shift from Phe-rich analogues, containing L-Phe3-D-Phe4 aromatic dipeptide unit, Trp-rich C L-Trp3-D-Trp4. For other residue position, Tyr7 preferentially incorporated above Trp7, minor incorporation Phe7 whole basic amino acid residue, time-sensitive Orn9 Lys9 incorporation. Modulation cyclodecapeptide profile does not correlate reported non-ribosomal peptide synthetase affinity, specifically for Trp positions, indicating additional supply-demand control B. parabrevis. These novel observations only importance purification selected complex, but also insight into microbial that extends beyond machinery.