Hypeptin

An antibiotic, named hypeptin, was isolated from the culture broth of a strain of Pseudomonas sp. The antibiotic was extracted with butanol and purified by chromatography on a Sephadex LH-20 column. The antibiotic is basic in nature. The dihydrochloride is soluble in aqueous alcohols and positive to ninhydrin and Sakaguchi's reaction. A molecular formula, C44H71N13O15.2HCl was indicated by microanalysis and secondary ion MS. The IR spectrum and acid hydrolysis indicated it to be a peptide antibiotic. The stereochemistries of the amino acids produced by hydrolysis were clarified by HPLC using a chiral column. The antibiotic is active in vitro against a wide variety of anaerobic bacteria and aerobic Gram-positive bacteria.

Hypeptin is a cyclodepsipeptide antibiotic produced by Lysobacter sp. K5869, isolated from an environmental sample by the iChip technology, dedicated to the cultivation of previously uncultured microorganisms. Hypeptin shares structural features with teixobactin and exhibits potent activity against a broad spectrum of gram-positive pathogens. Using comprehensive in vivo and in vitro analyses, we show that hypeptin blocks bacterial cell wall biosynthesis by binding to multiple undecaprenyl pyrophosphate-containing biosynthesis intermediates, forming a stoichiometric 2:1 complex. Resistance to hypeptin did not readily develop in vitro. Analysis of the hypeptin biosynthetic gene cluster (BGC) supported a model for the synthesis of the octapeptide. Within the BGC, two hydroxylases were identified and characterized, responsible for the stereoselective β-hydroxylation of four building blocks when bound to peptidyl carrier proteins. In vitro hydroxylation assays corroborate the biosynthetic hypothesis and lead to the proposal of a refined structure for hypeptin.