Scytodecamide from the Cultured Scytonema sp. UIC 10036 Expands the Chemical and Genetic Diversity of Cyanobactins

Cyanobactins are a large family of cyanobacterial ribosomally synthesized and post-translationally modified peptides (RiPPs) often associated with biological activities, such as cytotoxicity, antiviral, and antimalarial activities. They are traditionally described as cyclic molecules containing heterocyclized amino acids. However, this definition has been recently challenged by the discovery of short, linear cyanobactins containing three to five amino acids as well as cyanobactins containing no heterocyclized residues. Herein we report the discovery of scytodecamide ( 1 ) from the freshwater cyanobacterium Scytonema sp. UIC 10036. Structural elucidation based on mass spectrometry, 1D and 2D NMR spectroscopy, and Marfey's method revealed 1 to be a linear decapeptide with an N-terminal N-methylation and a C-terminal amidation. The genome of Scytonema sp. UIC 10036 was sequenced, and bioinformatic analysis revealed a cyanobactin-like biosynthetic gene cluster consistent with the structure of 1 . The discovery of 1 as a novel linear peptide containing an N-terminal N-methylation and a C-terminal amidation expands the chemical and genetic diversity of the cyanobactin family of compounds.     

Use of Lactobacillus paracasei isolated from whey for silver nanocomposite synthesis: Antiradical and antimicrobial properties against selected pathogens

The present research emphasizes the use of safe, inexpensive, and available whey using Lactobacillus paracasei as a source in silver nanocomposite synthesis as an alternative bioactive agent for dairy and biomedical applications. Through the multiinstrumental approach used in this study based on spectroscopic and microscopic methods as well as spectrometric techniques, the characterization and evaluation of silver composites and their antimicrobial and antiradical properties were enabled. Synthesized silver nanocomposites have been found in form of nanocrystals, naturally coated by an organic surface with high antimicrobial and antiradical properties. Furthermore, this work also presents an innovative approach regarding the organic surface (naturally secreted by the bacteria isolated from whey) of the core of nanoparticles, which has already been explored and therefore is starting to supplement the scientific approach concerning biologically synthesized nanoparticles. This work also presents a general frame on the resistance subject by performing the trial interaction of commercially available antibiotics (kanamycin and ampicillin) with new bioactive compounds that can create novel knowledge on complementing their action. Moreover, synthesized silver nanocomposites have shown great antioxidant and antimicrobial effects against various foodborne pathogens from dairy products and drug resistance pathogens found in the medical area to rank on the top of mortality rate.     

Bioengineering of Anti-Inflammatory Natural Products

Inflammatory processes occur as a generic response of the immune system and can be triggered by various factors, such as infection with pathogenic microorganisms or damaged tissue. Due to the complexity of the inflammation process and its role in common diseases like asthma, cancer, skin disorders or Alzheimer's disease, anti-inflammatory drugs are of high pharmaceutical interest. Nature is a rich source for compounds with anti-inflammatory properties. Several studies have focused on the structural optimization of natural products to improve their pharmacological properties. As derivatization through total synthesis is often laborious with low yields and limited stereoselectivity, the use of biosynthetic, enzyme-driven reactions is an attractive alternative for synthesizing and modifying complex bioactive molecules. In this minireview, we present an outline of the biotechnological methods used to derivatize anti-inflammatory natural products, including precursor-directed biosynthesis, mutasynthesis, combinatorial biosynthesis, as well as whole-cell and in vitro biotransformation.     

Unleashing the Power of Biocatalysts

Biocatalysis is a continuously expanding subfield in chemical biology. Herein, I describe two categories of biocatalysts, the LEGO-brick-like and game-console-like type, both of which can streamline the synthetic routes to therapeutics. A multi-disciplinary approach to expand the biocatalytic toolkit will open up opportunities to develop new therapeutics.     

Natural Voltage-Gated Sodium Channel Ligands: Biosynthesis and Biology

Natural product biosynthetic pathways are composed of enzymes that use powerful chemistry to assemble complex molecules. Small molecule neurotoxins are examples of natural products with intricate scaffolds which often have high affinities for their biological targets. The focus of this Minireview is small molecule neurotoxins targeting voltage-gated sodium channels (VGSCs) and the state of knowledge on their associated biosynthetic pathways. There are three small molecule neurotoxin receptor sites on VGSCs associated with three different classes of molecules: guanidinium toxins, alkaloid toxins, and ladder polyethers. Each of these types of toxins have unique structural features which are assembled by biosynthetic enzymes and the extent of information known about these enzymes varies among each class. The biosynthetic enzymes involved in the formation of these toxins have the potential to become useful tools in the efficient synthesis of VGSC probes.     

Mammalian-Like Inflammatory and Pro-Resolving Oxylipins in Marine Algae

Oxylipins constitute a family of oxidized fatty acids, that are well known as tissue hormones in mammals. They contribute to inflammation and its resolution. The major classes of these lipid mediators are inflammatory prostaglandins (PGs) and leukotrienes (LTs) as well as pro-resolving resolvins (Rvs). Understanding their biosynthetic pathways and modes of action is important for anti-inflammatory interventions. Besides mammals, marine algae also biosynthesize mammalian-like oxylipins and thus offer new opportunities for oxylipin research. They provide prolific sources for these compounds and offer unique opportunities to study alternative biosynthetic pathways to the well-known lipid mediators. Herein, we discuss recent findings on the biosynthesis of oxylipins in mammals and algae including an alternative pathway to prostaglandin E₂, a novel pathway to a precursor of leukotriene B₄, and the production of resolvins in algae. We evaluate the pharmacological potential of the algal metabolites with implications in health and disease.     

Functional Characterization of 3-Aminobenzoic Acid Adenylation Enzyme PctU and UDP-N-Acetyl-d-Glucosamine: 3-Aminobenzoyl-ACP Glycosyltransferase PctL in Pactamycin Biosynthesis

Pactamycin is an antibiotic produced by Streptomyces pactum with antitumor and antimalarial properties. Pactamycin has a unique aminocyclitol core that is decorated with 3-aminoacetophenone, 6-methylsaliciate, and an N,N-dimethylcarbamoyl group. Herein, we show that the adenylation enzyme PctU activates 3-aminobenzoic acid (3ABA) with adenosine triphosphate and ligates it to the holo form of the discrete acyl carrier protein PctK to yield 3ABA-PctK. Then, 3ABA-PctK is N-glycosylated with uridine diphosphate-N-acetyl-d -glucosamine (UDP-GlcNAc) by the glycosyltransferase PctL to yield GlcNAc-3ABA-PctK. Because 3ABA is known to be a precursor of the 3-aminoacetophenone moiety, PctU appears to be a gatekeeper that selects the appropriate 3-aminobenzoate starter unit. Overall, we propose that acyl carrier protein-bound glycosylated 3ABA derivatives are biosynthetic intermediates of pactamycin biosynthesis.     

Fe2O3/TNTs纳米复合材料的生物合成及其光催化性能研究

采用Shewanellaoneidensis MR-1合成Fe₂O₃/TNTs纳米复合材料,通过高分辨透射电子显微镜、扫描电子显微镜、X射线衍射仪、X射线光电子能谱仪、紫外-可见分光光度计等对Fe₂O₃/TNTs的结构和性能进行表征。结果表明,Fe₂O₃成功负载在TiO₂纳米管上;在紫外光照射下,Fe₂O₃/TNTs在60min内对苯胺蓝的脱色率可达到97.5%,表现出较好的光催化活性。Shewanellaoneidensis MR-1协同Fe₂O₃/TNTs纳米复合材料对苯胺蓝脱色率较So.neidensis MR-1提高了1.63%。