P450-Modified Ribosomally Synthesized Peptides with Aromatic Cross-Links.

Cyclization of linear peptides is an effective strategy to convert flexible molecules into rigid compounds, which is of great significance for enhancing the peptide stability and bioactivity. Despite significant advances in the past few decades, Nature and chemists' ability to macrocyclize linear peptides is still quite limited. P450 enzymes have been reported to catalyze macrocyclization of peptides through cross-linkers between aromatic amino acids with only three examples. Herein, we developed an efficient workflow for the identification of P450-modified RiPPs in bacterial genomes, resulting in the discovery of a large number of P450-modified RiPP gene clusters. Combined with subsequent expression and structural characterization of the products, we have identified 11 novel P450-modified RiPPs with different cross-linking patterns from four distinct classes. Our results greatly expand the structural diversity of P450-modified RiPPs and provide new insights and enzymatic tools for the production of cyclic peptides.

Building Streptomyces albus as a chassis for synthesis of bacterial terpenoids.

Terpenoids comprise the most chemically and structurally diverse family of natural products. In contrast to the huge numbers of terpenoids discovered from plants and fungi, only a relatively small number of terpenoids were reported from bacteria. Recent genomic data in bacteria suggest that a large number of biosynthetic gene clusters encoding terpenoids remain uncharacterized. In order to enable the functional characterization of terpene synthase and relevant tailoring enzymes, we selected and optimized an expression system based on a Streptomyces chassis. Through genome mining, 16 distinct bacterial terpene biosynthetic gene clusters were selected and 13 of them were successfully expressed in the Streptomyces chassis, leading to characterization of 11 terpene skeletons including three new ones, representing an ∼80% success rate. In addition, after functional expression of tailoring genes, 18 novel distinct terpenoids were isolated and characterized. This work demonstrates the advantages of a Streptomyces chassis which not only enabled the successful production of bacterial terpene synthases, but also enabled functional expression of tailoring genes, especially P450, for terpenoid modification.

Resistance and phylogeny guided discovery reveals structural novelty of tetracycline antibiotics.

Tetracyclines are a class of antibiotics that exhibited potent activity against a wide range of Gram-positive and Gram-negative bacteria, yet only five members were isolated from actinobacteria, with two of them approved as clinical drugs. In this work, we developed a genome mining strategy using a TetR/MarR-transporter, a pair of common resistance enzymes in tetracycline biosynthesis, as probes to find the potential tetracycline gene clusters in the actinobacteria genome database. Further refinement using the phylogenetic analysis of chain length factors resulted in the discovery of 25 distinct tetracycline gene clusters, which finally resulted in the isolation and characterization of a novel tetracycline, hainancycline (1). Through genetic and biochemical studies, we elucidated the biosynthetic pathway of 1, which involves a complex glycosylation process. Our work discloses nature's huge capacity to generate diverse tetracyclines and expands the chemical diversity of tetracyclines.

Exercise-Induced Hypoalgesia Following Proprioceptive Neuromuscular Facilitation and Resistance Training Among Individuals With Shoulder Myofascial Pain: Randomized Controlled Trial.

BACKGROUND: Various exercises can attenuate pain perception in healthy individuals and may interact with the descending pain modulation in the central nervous system. However, the analgesic effects of exercise in patients with myofascial pain can be disrupted by the pathological changes during chronic pain conditions. Thus, the exercises targeted on the facilitation of the sensory-motor interaction may have a positive impact on the restoration of the descending pain modulation and the analgesia effects. OBJECTIVE: This paper estimates the effect of proprioceptive neuromuscular facilitation (PNF) and resistance training on exercise-induced hypoalgesia (EIH) and conditioned pain modulation (CPM) among patients with myofascial pain syndrome. METHODS: A total of 76 female patients with myofascial pain syndrome (aged 18-30 years), with the pain in the upper trapezius and a visual analog scale score of greater than 30/100 mm, were enrolled in the study. Participants were randomly assigned into 3 intervention groups, including isometric (n=18, 24%), isotonic (n=19, 25%), and PNF (n=20, 26%) exercises, as well as 1 control group (n=19, 25%) with no intervention. Pressure pain threshold and the CPM responses at the myofascial trigger point, arm, and leg sites were assessed before and after the exercise session. The effective EIH response was reflected in the improvement of pressure pain thresholds. RESULTS: There was an increase in pressure pain thresholds and CPM responses at trigger point (P<.001 and P<.001), arm (P<.001 and P<.001), and leg sites (P<.001 and P=.03) in participants who performed PNF and isotonic exercise, while the isometric exercise only increased pressure pain thresholds at leg sites (P=.03). Compared with the control group, both the isotonic (P=.02) and PNF (P<.001) groups showed greater EIH responses at the trigger points. In comparison to the control group, only the PNF exercise (P=.01) significantly improved pressure pain thresholds and CPM responses at arm and leg sites compared to the control group. CONCLUSIONS: PNF, isotonic, and isometric exercises could lead to local and global EIH effects. The improvement in CPM response following PNF and isotonic exercises suggested that the EIH mechanisms of different resistance exercises may be attributed to the enhancement of the endogenous pain modulation via the motor-sensory interaction from the additional eccentric and dynamic muscle contraction. TRIAL REGISTRATION: Chinese Clinical Trial Registry ChiCtr202111090819166165; https://tinyurl.com/2ab93p7n.

Is it time to put traditional cold therapy in rehabilitation of soft-tissue injuries out to pasture?

Cold therapy has been used regularly as an immediate treatment to induce analgesia following acute soft-tissue injuries, however, a prolonged ice application has proved to delay the start of the healing and lengthen the recovery process. Hyperbaric gaseous cryotherapy, also known as neurocryostimulation, has shown the ability to overcome most of the limitations of traditional cold therapy, and meanwhile promotes the analgesic and anti-inflammatory effects well, but the current existing studies have shown conflicting results on its effects. Traditional cold therapy still has beneficial effect especially when injuries are severe and swelling is the limiting factor for recovery after soft-tissue injuries, and therefore no need to be entirely put out to pasture in the rehabilitation practice. Strong randomized controlled trials with good methodological quality are still needed in the future to evaluate the effects of different cryotherapy modalities.

Pleosporalins H and I, two new heptaketides from the endophytic fungus Pleosporales sp. F46 by using OSMAC strategy.

Two new heptaketides, pleosporalins H and I (1 and 2), as well as seven biosynthetically related known polyketides (3-9) were isolated from the endophytic fungus, Pleosporales sp. F46 by employing the one strain-many compounds (OSMAC) approach. The planar, relative and absolute structures of these compounds were identified by extensive spectroscopic analysis including HRMS, NMR, optical rotations and ECD calculations. The cytotoxic efficiencies of all isolated compounds 1-9 were evaluated against four cancer cell lines A549, CT-26, MCF-7 and MDA-MB-231.

Induced production of steroids by co-cultivation of two endophytes from Mahonia fortunei.

A new ergosterol derivative, 23R-hydroxy-(20Z,24R)-ergosta-4,6,8(14),20(22)-tetraen-3-one (1), and a biosynthetically related known compound, (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (2), were isolated from the co-culture between endophytic fungus Pleosporales sp. F46 and endophytic bacterium Bacillus wiedmannii Com1 both inhibiting in the medicinal plant Mahonia fortunei. The structure of the new compound 1 was determined by extensive spectroscopic analysis using HRMS and NMR, together with the modified Mosher's ester method. This is the first example of isolation of a ergosterol derivative with a Δ20(22)-double bond in the side chain. Compound 1 exhibited moderate antibacterial efficacy against Staphylococcus aureus and no obvious cytotoxic activities against the cancer cell lines A549, MDA-MB-231 and Hct116. Our results not only reveal that compound 1 is a potent antibacterial lead compound, but also highlight the powder of co-cultivation for inducing the production of cryptic natural products from endophytes derived from the same host plant.

[Mechanism of Nampt gene expression regulation].

Nicotinamide phosphoribosyltransferase (NAMPT), also known as pre-B cell colony-enhancing factor (PBEF) or visfatin, is a crucial rate-limiting enzyme of NAD biosynthetic pathway. It may affect the metabolism, inflammatory response, cell proliferation, differentiation, and apoptosis, especially the aging and other physiological progresses through regulating NAD biosynthesis and nonenzyme routes in the organisms and cells. This review mainly focuses on recent progresses in the expression modulation and feedback regulation of Nampt gene.