Structure-based design of agarase AgWH50C from Agarivorans gilvus WH0801 to enhance thermostability.

AgWH50C, an exo-ß-agarase of GH50 isolated from Agarivorans gilvus WH0801, plays a key role in the enzymatic production of neoagarobiose, which has great application prospect in the cosmetics and pharmaceutical industry. In contrast, the poor thermostability becomes the main obstructive factor of glycoside hydrolase (GH) family 50 agarases, including AgWH50C. Herein, based on the AgWH50C crystal structure, we designed several mutants by a multiple cross-linked rational design protocol used thermostability predicting softwares ETSS, PoPMuSiC, and HotMuSiC. To our surprise, the mutant K621F increased its relative activity by as much as 45% and the optimal temperature increased to 38 °C compared to that of wild-type, AgWH50C (30 °C). The thermostability of K621F also exhibited a substantial improvement. Considering that the gelling temperature of the agarose is higher than 35 °C, K621F can be used to hydrolyze agarose for neoagarobiose production.

Colorimetric determination of the early biomarker hypoxia-inducible factor-1 alpha (HIF-1α) in circulating exosomes by using a gold seed-coated with aptamer-functionalized Au@Au core-shell peroxidase mimic.

An ultra-sensitive method is described here for the determination of HIF-1α (an early biomarker for myocardial infarction) in circulating exosomes in serum. Gold nanospheres were functionalized with a HIF-1α-binding aptamer via sulfydryl chemistry. The apt-AuNP-coated gold seeds were grown by seed-mediated growth, and this significantly increased the peroxidase-mimicking property the nanoparticles. A chromogenic system composed of 3,3'5,5'-tetramethylbenzidine and hydrogen peroxide was used. Absorbance at 652 nm increases linearly in the 0.3 to 200 ng L-1 HIF-1α concentration range, and the limit of detection is 0.2 ng L-1. The method was tested by analyzing rat serum from isoproterenol (ISO)-induced myocardial infarction. It allows HIF-1α to be directly determined in a 25 µL sample without preconcentration. The assay is not interfered by the polydispersity of exosomes released under either health and disease conditions. Graphical abstractGold nanospheres were functionalized with a HIF-1α-binding aptamer via sulfydryl chemistry. Nanosized gold seed particles were then modified with the functionalized gold nanospheres, and this strongly increases the peroxidase-mimicking activity of the nanomaterial. By using the tetramethylbenzidine/H2O2 chromogenic system, the absorbance at 652 nm increases linearly in the 0.3 to 200 ng L-1 HIF-1α concentration range.

Genome-wide characterization of simple sequence repeats in Pyrus bretschneideri and their application in an analysis of genetic diversity in pear.

BACKGROUND: Pear (Pyrus spp.) is an economically important temperate fruit tree worldwide. In the past decade, significant progress has been made in pear molecular genetics based on DNA research, but the number of molecular markers is still quite limited, which hardly satisfies the increasing needs of geneticists and breeders. RESULTS: In this study, a total of 156,396 simple sequence repeat (SSR) loci were identified from a genome sequence of Pyrus bretschneideri 'Dangshansuli'. A total of 101,694 pairs of SSR primers were designed from the SSR loci, and 80,415 of the SSR loci were successfully located on 17 linkage groups (LGs). A total of 534 primer pairs were synthesized and preliminarily screened in four pear cultivars, and of these, 332 primer pairs were selected as clear, stable, and polymorphic SSR markers. Eighteen polymorphic SSR markers were randomly selected from the 332 polymorphic SSR markers in order to perform a further analysis of the genetic diversity among 44 pear cultivars. The 14 European pears and their hybrid materials were clustered into one group (European pear group); 29 Asian pear cultivars were clustered into one group (Asian pear group); and the Zangli pear cultivar 'Deqinli' from Yunnan Province, China, was grouped in an independent group, which suggested that the cultivar 'Deqinli' is a distinct and valuable germplasm resource. The population structure analysis partitioned the 44 cultivars into two populations, Pop 1 and Pop 2. Pop 2 was further divided into two subpopulations. Results from the population structure analysis were generally consistent with the results from the UPGMA cluster analysis. CONCLUSIONS: The results of the present study showed that the use of next-generating sequencing to develop SSR markers is fast and effective, and the developed SSR markers can be utilized by researchers and breeders for future pear improvement.

Mechanisms of acquired resistance to HER2-Positive breast cancer therapies induced by HER3: A comprehensive review.

Receptor tyrosine kinases (RTKs) are cell surface receptors with kinase activity that play a crucial role in diverse cellular processes. Among the RTK family members, Human epidermal growth factor receptor 2 (HER2) and HER3 are particularly relevant to breast cancer. The review delves into the complexities of receptor tyrosine kinase interactions, resistance mechanisms, and the potential of anti-HER3 drugs, offering valuable insights into the clinical implications and future directions in this field of study. It assesses the potential of anti-HER3 drugs, such as pertuzumab, in overcoming resistance observed in HER2-positive breast cancer therapies. The review also explores the resistance mechanisms associated with various drugs, including trastuzumab, lapatinib, and PI3K inhibitors, providing insights into the intricate molecular processes underlying resistance development. The review concludes by emphasizing the necessity for further clinical trials to assess the efficacy of HER3 inhibitors and the potential of developing safe and effective anti-HER3 treatments to improve treatment outcomes for patients with HER2-positive breast cancer.

Hydrogen sulfide functions as a micro-modulator bound at the copper active site of Cu/Zn-SOD to regulate the catalytic activity of the enzyme.

The present study examines whether there is a mechanism beyond the current concept of post-translational modifications to regulate the function of a protein. A small gas molecule, hydrogen sulfide (H2S), was found to bind at active-site copper of Cu/Zn-SOD using a series of methods including radiolabeled binding assay, X-ray absorption near-edge structure (XANES), and crystallography. Such an H2S binding enhanced the electrostatic forces to guide the negatively charged substrate superoxide radicals to the catalytic copper ion, changed the geometry and energy of the frontier molecular orbitals of the active site, and subsequently facilitated the transfer of an electron from the superoxide radical to the catalytic copper ion and the breakage of the copper-His61 bridge. The physiological relevance of such an H2S effect was also examined in both in vitro and in vivo models where the cardioprotective effects of H2S were dependent on Cu/Zn-SOD.

Discovery of a Highly Potent and Selective Dual PROTAC Degrader of CDK12 and CDK13.

Selective degradation of the cyclin-dependent kinases 12 and 13 (CDK12/13) presents a novel therapeutic opportunity for triple-negative breast cancer (TNBC), but there is still a lack of dual CDK12/13 degraders. Here, we report the discovery of the first series of highly potent and selective dual CDK12/13 degraders by employing the proteolysis-targeting chimera (PROTAC) technology. The optimal compound 7f effectively degraded CDK12 and CDK13 with DC50 values of 2.2 and 2.1 nM, respectively, in MDA-MB-231 breast cancer cells. Global proteomic profiling demonstrated the target selectivity of 7f. In vitro, 7f suppressed expression of core DNA damage response (DDR) genes in a time- and dose-dependent manner. Further, 7f markedly inhibited proliferation of multiple TNBC cell lines including MFM223, with an IC50 value of 47 nM. Importantly, 7f displayed a significantly improved antiproliferative activity compared to the structurally similar inhibitor 4, suggesting the potential advantage of a CDK12/13 degrader for TNBC targeted therapy.

Complete genome sequence of Agarivorans gilvus WH0801(T), an agarase-producing bacterium isolated from seaweed.

Agarivorans gilvus WH0801(T), an agarase-producing bacterium, was isolated from the surface of seaweed. Here, we present the complete genome sequence, which consists of one circular chromosome of 4,416,600 bp with a GC content of 45.9%. This genetic information will provide insight into biotechnological applications of producing agar for food and industry.