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A facile method for the quick discovery and quantification of isonitrile compounds from microbial cultures was established based on the isonitrile-tetrazine click reaction. This method was successfully applied to the rediscovery of diisonitrile anti-botic SF2768 from an unknown strain Streptomyces tsukubensis. Finally, an in situ reduction further enabled bioorthogonal ligation of primary and secondary isonitriles for the first time.

SiO x coating is an effective strategy to prolong the cycling stability of Si-based anodes due to the robust interaction between Si and the SiO x layer. However, the SiO x layer-protected Si anode is limited by the relatively low initial Coulombic efficiency and sluggish Li+ diffusion ability induced by the SiO x layer. Herein, we present the preparation of selectively prelithiated Si@SiO x (Si@Li2SiO3) anode by using a facile strategy to resolve the above issues. As the anode for lithium ion batteries, Si@Li2SiO3 exhibits a high initial Coulombic efficiency (ICE) of 89.1%, an excellent rate performance (959 mA h g-1 at 30 A g-1), and a superior capacity retention (3215 mA h g-1). The full cell with LiFePO4 cathode and Si@Li2SiO3 anodes is successfully assembled, disclosing a high ICE of 91.1% and excellent long cycling stability. The superior electrochemical performance of Si@Li2SiO3 can be attributed to the coating layer, which can strengthen the integrity of the electrode, decrease irreversible reactions, and provide efficient Li+ diffusion channels.

Muraymycins belong to a family of nucleoside antibiotics that have a distinctive disaccharide core consisting of 5-amino-5-deoxyribofuranose (ADR) attached to 6'- N-alkyl-5'- C-glycyluridine (GlyU). Here, we functionally assign and characterize six enzymes from the muraymycin biosynthetic pathway involved in the core assembly that starts from uridine monophosphate (UMP). The biosynthesis is initiated by Mur16, a nonheme Fe(II)- and α-ketoglutarate-dependent dioxygenase, followed by four transferase enzymes: Mur17, a pyridoxal-5'-phosphate (PLP)-dependent transaldolase; Mur20, an aminotransferase; Mur26, a pyrimidine phosphorylase; and Mur18, a nucleotidylyltransferase. The pathway culminates in glycosidic bond formation in a reaction catalyzed by an additional transferase enzyme, Mur19, a ribosyltransferase. Analysis of the biochemical properties revealed several noteworthy discoveries including that (i) Mur16 and downstream enzymes can also process 2'-deoxy-UMP to generate a 2-deoxy-ADR, which is consistent with the structure of some muraymycin congeners; (ii) Mur20 prefers l-Tyr as the amino donor source; (iii) Mur18 activity absolutely depends on the amine functionality of the ADR precursor consistent with the nucleotidyltransfer reaction occurring after the Mur20-catalyzed aminotransfer reaction; and (iv) the bona fide sugar acceptor for Mur19 is (5' S,6' S)-GlyU, suggesting that ribosyltransfer occurs prior to N-alkylation of GlyU. Finally, a one-pot, six-enzyme reaction was utilized to generate the ADR-GlyU disaccharide core starting from UMP.

Diketopiperazines (DKPs) are a large group of natural products with diverse structures and biological activities. Bicyclomycin is a broad-spectrum DKP antibiotic with unique structure and function: it contains a highly oxidized bicyclic [4.2.2] ring and is the only known selective inhibitor of the bacterial transcription termination factor, Rho. Here, we identify the biosynthetic gene cluster for bicyclomycin containing six iron-dependent oxidases. We demonstrate that the DKP core is made by a tRNA-dependent cyclodipeptide synthase, and hydroxylations on two unactivated sp3 carbons are performed by two mononuclear iron, α-ketoglutarate-dependent hydroxylases. Using bioinformatics, we also identify a homologous gene cluster prevalent in a human pathogen Pseudomonas aeruginosa. By observing bicyclomycin production from heterologously expression of the pseudomonas bcm gene cluster, we establish P. aeruginosa as a new producer of bicyclomycin. Our work uncovers the biosynthetic pathway for bicyclomycin and sheds light on the intriguing oxidation chemistry that converts a simple DKP into a powerful antibiotic.

B,N-Co-doped graphene supported sulfur (S@BNG) composite is synthesized by using melamine diborate as precursor. XPS spectra illustrates that BNG with a high percentage and dispersive B, N (B = 13.47%, N = 9.17%) and abundant pyridinic-N and N–B/N═B bond, show strong interaction with Li2Sx proved by adsorption simulation experiments. As cathode for Li–S half cell, S@BNG with a sulfur content of 75% displays a reversible capacity of 765 mA h g–1 at 1 C even after 500 cycles (a low fading rate of 0.027% per cycle). Even at a high sulfur loading of 4.73 mg cm–2, S@BNG still shows a high and stable areal capacity of 3.5 mA h cm–2 after 48 cycles. When S@BNG composite as cathode combines with high performance lithiated Ge anode (discharge capacity of 1138 mA h g–1 over 1000 cycles at 1 C in half cell), the assembled Ge–S full battery exhibits a superior capacity of 530 mA h g–1 over 500 cycles at the rate of 1 C.