RESUMEN
We report a novel family of natural lipoglycopeptides produced by Streptomyces sp. INA-Ac-5812. Two major components of the mixture, named gausemycinsâ A and B, were isolated, and their structures were elucidated. The compounds are cyclic peptides with a unique peptide core and several remarkable structural features, including unusual positions of d-amino acids, lack of the Ca2+ -binding Asp-X-Asp-Gly (DXDG) motif, tyrosine glycosylation with arabinose, presence of 2-amino-4-hydroxy-4-phenylbutyric acid (Ahpb) and chlorinated kynurenine (ClKyn), and N-acylation of the ornithine side chain. Gausemycins have pronounced activity against Gram-positive bacteria. Mechanistic studies highlight significant differences compared to known glyco- and lipopeptides. Gausemycins exhibit only slight Ca2+ -dependence of activity and induce no pore formation at low concentrations. Moreover, there is no detectable accumulation of cell wall biosynthesis precursors under treatment with gausemycins.
Asunto(s)
Lipoglucopéptidos/aislamiento & purificación , Streptomyces/química , Lipoglucopéptidos/química , Conformación MolecularRESUMEN
A novel actinobacterium, strain K3-2T, was isolated in pure culture from a thawing ancient ice wedge at Mammoth Mountain (Eastern Siberia, Russia). Colonies of strain K3-2T were yellowish orange; cells had the fine structure typical of Gram-positive bacteria, were non-motile short rods and were non-spore-forming. Strain K3-2T was mesophilic (optimum growth at 28 °Ð¡), but capable of growing at 4 °Ð¡. The cell-wall peptidoglycan of strain K3-2T contained lysine (the diagnostic diamino acid), glutamic acid, alanine, ornithine, glycine and serine. The polar lipids were phosphatidylglycerol, lysophosphatidylserine, three unidentified phospholipids and glycolipids. The major fatty acids were anteiso-C15â:â0 and C16â:â0. The only menaquinone detected was MK-8(H4). 16S rRNA gene analysis indicated that strain K3-2T belongs to the genus Serinibacter. The closest taxonomically described relatives were Serinibacter salmoneus Kis4-28T and Serinibacter tropicus PS-14-7T, with 97.20 and 97.20â% 16 s rRNA gene sequence similarity, respectively. The average nucleotide identity value of the whole genome sequence between strain K3-2T and S. salmoneus Kis4-28T was 78.9â%. DNA-DNA relatedness values between strain K3-2T and S. salmoneus DSM 21801T (=Kis4-28T) and S. tropicus VKPM Ac 2044T (=PS-14-7T) were 41 and 47â%. Thus, strain K3-2T represents a novel species of the genus Serinibacter for which the name Serinibacter arcticus sp. nov. is proposed. The type strain is K3-2T (DSM 103859T=VKM ÐÑ-2719T).
Asunto(s)
Actinobacteria/clasificación , Hielo , Filogenia , Actinobacteria/aislamiento & purificación , Técnicas de Tipificación Bacteriana , Composición de Base , Pared Celular/química , ADN Bacteriano/genética , Ácidos Grasos/química , Glucolípidos/química , Hibridación de Ácido Nucleico , Peptidoglicano/química , Fosfolípidos/química , Pigmentación , ARN Ribosómico 16S/genética , Análisis de Secuencia de ADN , Siberia , Vitamina K 2/análogos & derivados , Vitamina K 2/químicaRESUMEN
Phaeospirillum fulvum MGU-K5 is an anoxygenic, purple, photoheterotrophic, nonsulfur alphaproteobacterium. Unlike most purple nonsulfur bacteria, MGU-K5 is unable to grow aerobically under chemoorganotrophic conditions. Here, we present the draft genome sequence of P. fulvum to provide insights into its physiology.