Biosynthesis of Nonribosomal Peptides Chitinimides Reveal a Special Type of Thioesterase Domains.

Non-ribosomal peptide synthetases (NRPSs) and their tailored enzymes have diverse biological functions. In this study, we investigated the biosynthesis and function of chitinimides, which belong to the non-ribosomal peptide (NRP) subfamily featuring a pyrrolidine-containing part (X part) connected to the polypeptide chain via an ester bond. A conserved gene cassette, chmHIJK, is responsible for oxyacylation of the pyrrolidine moiety in the X part.

Performance of 3D printing biomimetic conch shell and pearl shell hybrid design composites under quasi-static three-point bending load.

The failure process of biomimetic hybrid design composite composed of layers of conch shell and pearl shell was studied through quasi-static three-point bending experiments and numerical simulations. The biomimetic conch shell structure with inclined angles serves as the upper layer of the hybrid structure, while the biomimetic pearl shell structure with traditional brick and mud structure serves as the lower layer of the hybrid structure, forming a hybrid design structure. Four inclined angles were designed for the structural units of the conch shell, namely 15°, 30°, 45°, and 60°.

Leader peptide removal in lasso peptide biosynthesis based on penultimate isoleucine residue.

Lasso peptides are ribosomally synthesized peptides that undergo post-translational modifications including leader peptide removal by B (or the segregated B1 and B2) proteins and core peptide macrolactamization by C proteins to form a unique lariat topology. A conserved threonine residue at the penultimate position of leader peptide is hitherto found in lasso peptide precursors and shown to be a critical recognition element for effective enzymatic processing. We identified a lasso peptide biosynthetic gene cluster () from FA350, a Gram-negative and facultatively prey-dependent bacterium that belongs to a novel bacterial order in the class .

Controllable Exfoliation of MOF-Derived Van Der Waals Superstructure into Ultrathin 2D B/N Co-Doped Porous Carbon Nanosheets: A Superior Catalyst for Ambient Ammonia Electrosynthesis.

The electrocatalytic nitrogen reduction reaction (NRR) to synthesize NH under ambient conditions is a promising alternative route to the conventional Haber-Bosch process, but it is still a great challenge to develop electrocatalysts' high Faraday efficiency and ammonia yield. Herein, a facile and efficient exfoliation strategy to synthesize ultrathin 2D boron and nitrogen co-doped porous carbon nanosheets (B/NC NS) via a metal-organic framework (MOF)-derived van der Waals superstructure, is reported. The results of experiments and theoretical calculations show that the doping of boron and nitrogen can modulate the electronic structure of the adjacent carbon atoms; which thus, promotes the competitive adsorption of nitrogen and reduces the energy required for ammonia synthesis.

Unusual Post-Translational Modifications in the Biosynthesis of Lasso Peptides.

Lasso peptides are a subclass of ribosomally synthesized and post-translationally modified peptides (RiPPs) and feature the threaded, lariat knot-like topology. The basic post-translational modifications (PTMs) of lasso peptide contain two steps, including the leader peptide removal of the ribosome-derived linear precursor peptide by an ATP-dependent cysteine protease, and the macrolactam cyclization by an ATP-dependent macrolactam synthetase. Recently, advanced bioinformatic tools combined with genome mining have paved the way to uncover a rapidly growing number of lasso peptides as well as a series of PTMs other than the general class-defining processes.

Adsorption in Reversed Order of C Hydrocarbons on an Ultramicroporous Fluorinated Metal-Organic Framework.

Metal-organic frameworks have been widely studied in the separation of C hydrocarbons, which usually preferentially bind unsaturated hydrocarbons with the order of acetylene (C H )>ethylene (C H )>ethane (C H ). Herein, we report an ultramicroporous fluorinated metal-organic framework Zn-FBA (H FBA=4,4'-(hexafluoroisopropylidene)bis(benzoic acid)), shows a reversed adsorption order characteristic for C hydrocarbons, that the uptake for C hydrocarbons of the framework and the binding affinity between the guest molecule and the framework follows the order C H >C H >C H . Density-functional theory calculations confirm that the completely reversed adsorption order behavior is attributed to the close van der Waals interactions and multiple cooperative C-H⋅⋅⋅F hydrogen bonds between the framework and C H .

characterization of a nitro-forming oxygenase involved in 3-(-2'-aminocyclopropyl)alanine biosynthesis.

characterization experiments revealed the formations of 3-(-2'-aminocyclopropyl)alanine ((3-Acp)Ala) and 3-(-2'-nitrocyclopropyl)alanine ((3-Ncp)Ala) are originated via two homologous proteins, BelK and HrmI, which regioselectively catalyze the Nε-oxygenation of l-lysine. The two enzymes belong to the emerging heme-oxygenase-like diiron oxidase and oxygenase (HDO) superfamily and the catalytic center of BelK is validated by homology modeling and site-directed mutations. Based on the characterization, the biosynthetic pathways of (3-Acp)Ala and (3-Ncp)Ala are proposed.

Rational construction of genome-reduced Burkholderiales chassis facilitates efficient heterologous production of natural products from proteobacteria.

Heterologous expression of biosynthetic gene clusters (BGCs) avails yield improvements and mining of natural products, but it is limited by lacking of more efficient Gram-negative chassis. The proteobacterium Schlegelella brevitalea DSM 7029 exhibits potential for heterologous BGC expression, but its cells undergo early autolysis, hindering further applications. Herein, we rationally construct DC and DT series genome-reduced S.

Obesity-induced overexpression of miRNA-24 regulates cholesterol uptake and lipid metabolism by targeting SR-B1.

Scavenger Receptor B1 (SR-B1) is an 82 kDa integral membrane glycoprotein that mediates selective uptake of high-density lipoprotein cholesteryl ester (CE) in vitro and in vivo. Previously, we defined several kinds of regulatory mechanisms of SR-B1 expression and function. Here, we have dissected the function of a novel miR-24 on SR-B1 expression, HDL uptake and lipid metabolism.

[Risk factors for the kidney stones: a hospital-based case-control study in a distric hospital in Beijing].

Objective: To explore the risk and protective factors of kidney calculi in order to put forward theoretical basis for preventive and control measures.

Methods: A 1:1 matched case-control study was performed using data from a hospital in Beijing. The case group included 100 inpatients who were diagnosed kidney calculi using B ultrasonic, X-ray and intravenous pyelography during the survey while other 100 urolithiasis and endocrine disease excluded inpatients who shared the same sex, within five years gap to the case group inpatients were for the control group.