OBJECTIVE: To confirm the sequence of a null allele HLA-C*08:127N produced by a base insertion. METHODS: PCR sequence-specific oligonucleotide probe (SSOP) and PCR sequence-based typing (SBT) were used for HLA routine detection, which discovered abnormal sequence maps of HLA-C in one acute myeloid leukemia patient. The sequence of the above loci was confirmed by next generation sequencing (NGS) technology. RESULTS: The SSOP typing result showed that HLA-C locus was C*03:04, C*08:01, while the sequence was suspected to be inserted or deleted in exon 3 by SBT, and finally confirmed by NGS as C*03:04, C*08:127N. CONCLUSION When base insertion produces HLA null alleles, SBT analysis software cannot provide correct results, but NGS technology can more intuitively obtain accurate HLA typing results.
Humans ; Alleles ; High-Throughput Nucleotide Sequencing ; HLA-C Antigens/genetics* ; Histocompatibility Testing ; Polymerase Chain Reaction ; Leukemia, Myeloid, Acute/genetics* ; Sequence Analysis, DNA ; Mutagenesis, Insertional ; Exons

Tripterifordin and neotripterifordin are important ent-kaurane diterpenoids in the Chinese medicinal herb Tripterygium wilfordii, possessing significant anti-HIV(human immunodeficiency virus) activity. On the basis of elucidating the natural biosynthetic pathways of these compounds, heterologous production with microbial cell factories can help to alleviate the reliance on plant resources and provide abundant raw materials for sustainable production. TwKO is the first CYP450 enzyme involved in the biosynthesis of tripterifordin and neotripterifordin. This study aimed to enhance the catalytic activity of TwKO by site-directed mutagenesis to benefit the production of tripterifordin and neotripterifordin in yeast. The AlphaFold DB established based on the AlphaFold 2 was employed to obtain the protein model of TwKO. According to multiple sequence alignments and principles of natural evolution, the key residues influencing the binding of TwKO to the substrate were identified. Subsequently, functional characterization of the mutants were conducted in Saccharomyces cerevisiae. A total of 71 mutants were obtained, among which 11 and 11 mutants had the abilities of enhancing the production of 16α-hydroxy-ent-kaurenol and 16α-hydroxy-ent-kaurenoic acid, respectively. In addition, 10 mutants could increase the proportion of the oxidation product of 16α-hydroxy-ent-kaurenol. In particular, R304 was identified as a key residue affecting the catalytic specificity of TwKO, the mutation of which led to the specific prodiction of 16α-hydroxy-ent-kaurenol. This study was the first to reveal the key residue affecting the catalytic activity of TwKO and obtained the mutants with increased TwKO activity, lay a foundation for the biosynthesis of tripterifordin and neotripterifordin.
Tripterygium/chemistry* ; Mutagenesis, Site-Directed ; Diterpenes, Kaurane/chemistry* ; Plant Proteins/chemistry* ; Cytochrome P-450 Enzyme System/chemistry* ; Saccharomyces cerevisiae/metabolism*

In this study, a single base editing system was used to edit the FecB and GDF9 gene to achieve a targeted site mutation from A to G and from C to T in Ouler Tibetan sheep fibroblasts, and to test its editing efficiency. Firstly, we designed and synthesized sgRNA sequences targeting FecB and GDF9 genes of Ouler Tibetan sheep, followed by connection to epi-ABEmax and epi-BE4max plasmids to construct vectors and electrotransfer into Ouler Tibetan sheep fibroblasts. Finally, Sanger sequencing was performed to identify the target point mutation of FecB and GDF9 genes positive cells. T-A cloning was used to estimate the editing efficiency of the single base editing system. We obtained gRNA targeting FecB and GDF9 genes and constructed the vector aiming at mutating single base of FecB and GDF9 genes in Ouler Tibetan sheep. The editing efficiency for the target site of FecB gene was 39.13%, whereas the editing efficiency for the target sites (G260, G721 and G1184) of GDF9 gene were 10.52%, 26.67% and 8.00%, respectively. Achieving single base mutation in FecB and GDF9 genes may facilitate improving the reproduction traits of Ouler Tibetan sheep with multifetal lambs.
Animals ; Sheep/genetics* ; Gene Editing ; Tibet ; Mutation ; Phenotype ; Mutagenesis, Site-Directed

The aim of this study was to construct Chlorella mutants deficient in chlorophyll synthesis by atmospheric pressure room temperature plasma (ARTP) mutagenesis, and screen novel algal species with very low chlorophyll content which is suitable for protein production by fermentation. Firstly, the lethal rate curve of mixotrophic wild type cells was established by optimizing the mutagenesis treatment time. The mixotrophic cells in early exponential phase were treated by the condition of over 95% lethal rate, and 4 mutants with the visual change of colony color were isolated. Subsequently, the mutants were cultured in shaking flasks heterotrophically for evaluation of their protein production performance. P. ks 4 mutant showed the best performance in Basal medium containing 30 g/L glucose and 5 g/L NaNO₃. The protein content and productivity reached 39.25% dry weight and 1.15 g/(L·d), with an amino acid score of 101.34. The chlorophyll a content decreased 98.78%, whereas chlorophyll b was not detected, and 0.62 mg/g of lutein content made the algal biomass appear golden yellow. This work provides a novel germplasm, the mutant P. ks 4 with high yield and high quality, for alternative protein production by microalgal fermentation.
Chlorella/metabolism* ; Chlorophyll A/metabolism* ; Plant Breeding ; Mutagenesis ; Chlorophyll/metabolism* ; Biomass ; Microalgae

Epidermal growth factor receptor exon 20 insertion (EGFR ex20ins) is one of the earliest driver gene activation mutations in non-small cell lung cancer (NSCLC). However, due to the unique structure of protein variation caused by this mutation, most patients with EGFR ex20ins mutation (except A763_Y764insFQEA) have poor response to the launched first/second/third generation EGFR-tyrosine kinase inhibitors (EGFR-TKIs). With the successive approval of new specific targeted drugs for EGFR ex20ins in Food and Drug Administration (FDA) and other national regulatory agencies, the development and clinical research of targeted drugs for EGFR ex20ins in China have also developed rapidly and Mobocertinib has been approved recently in China. It is worth noting that EGFR ex20ins is a variant type with strong molecular heterogeneity. How to detect it comprehensively and accurately in clinical practice, so as to enable more patients to benefit from targeted therapy, is a very important and urgent problem to be solved. This review introduces the molecular typing of EGFR ex20ins, then discusses the importance of EGFR ex20ins detection and the differences of various detection methods, and summarizes the research and development of new drugs progress of EGFR ex20ins, in order to optimize the diagnosis and treatment path of EGFR ex20ins patients by selecting accurate, rapid and appropriate detection methods, so as to improve the clinical benefits of the patients.
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United States ; Humans ; Carcinoma, Non-Small-Cell Lung ; Mutagenesis, Insertional ; Lung Neoplasms ; ErbB Receptors ; Exons

Polygonum cuspidatum polyketide synthase 1 (PcPKS1) has the catalytic activity of chalcone synthase (CHS) and benzylidene acetone synthase (BAS), which can catalyze the production of polyketides naringenin chalcone and benzylidene acetone, and then catalyze the synthesis of flavonoids or benzylidene acetone. In this study, three amino acid sites (Thr133, Ser134, Ser33) that may affect the function of PcPKS1 were identified by analyzing the sequences of PcPKS1, the BAS from Rheum palmatum and the CHS from Arabidopsis thaliana, as well as the conformation of the catalytic site of the enzyme. Molecular modification of PcPKS1 was carried out by site-directed mutagenesis, and two mutants were successfully obtained. The in vitro enzymatic reactions were carried out, and the differences in activity were detected by high performance liquid chromatography (HPLC). Finally, mutants T133LS134A and S339V with bifunctional activity were obtained. In addition to bifunctional activities of BAS and CHS, the modified PcPKS1 had much higher BAS activity than that of the wild type PcPKS1 under the conditions of pH 7.0 and pH 9.0, respectively. It provides a theoretical basis for future use of PcPKS1 in genetic engineering to regulate the biosynthesis of flavonoids and raspberry ketones.
Amino Acid Sequence ; Fallopia japonica/metabolism* ; Polyketide Synthases/chemistry* ; Acetone ; Mutagenesis, Site-Directed ; Flavonoids/metabolism* ; Acyltransferases/metabolism*

With the development of precision diagnosis and treatment for non-small cell lung cancer (NSCLC), the epidermal growth factor receptor (EGFR) exon 20 insertion (ex20ins) mutations, as a rare subset of EGFR mutaions, have gradually attracted attention recently. The heterogeneity of EGFR ex20ins mutations is very high, different variants have different clinical benefits, and the prognosis is extremely poor. The available traditional treatment outcomes are poor in patients with EGFR ex20ins positive NSCLC and polymerase chain reaction (PCR) tests would miss aprocimately 50% of the variants. Therefore, high attention should be paid to EGFR ex20ins positive NSCLC during the clinical practice. The expert panel has formed a consensus on the standardized clinical diagnosis and treatment of EGFR ex20ins mutation NSCLC through reference to literature and clinical data, and combined with the experts' own clinical experience, the consensus recommendations including clinicopathologic characteristics, therapies, testing methods and recent relevant clinical trials for NSCLC patients with EGFR ex20ins mutation, in order to provide medication reference for clinical physicians at all levels.
Humans ; Carcinoma, Non-Small-Cell Lung/therapy* ; Consensus ; ErbB Receptors/genetics* ; Exons ; Lung Neoplasms/therapy* ; Mutagenesis, Insertional

In order to develop a simple and efficient site-directed mutagenesis solution, the Gibson assembly technique was used to clone the cyclin dependent kinase 4 gene with single or double site mutations, with the aim to simplify the overlap extension PCR. The gene fragments containing site mutations were amplified using a strategy similar to overlap extension PCR. Meanwhile, an empty plasmid was digested by double restriction endonucleases to generate a linearized vector with a short adaptor overlapping with the targeted gene fragments. The gene fragments were directly spliced with the linearized vector by Gibson assembly in an isothermal, single-reaction, creating a recombinant plasmid. After the recombinant plasmids were transformed into competent Escherichia coli DH5α, several clones were screened from each group. Through restriction analysis and DNA sequencing, it was found that the randomly selected clones were 100% target mutants. Since there was neither tedious multiple-round PCR amplification nor frequent DNA extraction operation, and there was no need to digest the original plasmid, this protocol circumvents many factors that may interfere with the conventional site-directed mutagenesis. Hence, genes with single or multiple mutations could be cloned easily and efficiently. In summary, the major defects associated with overlap extension PCR and rolling circle amplification were circumvented in this protocol, making it a good solution for site-directed mutagenesis.
Clone Cells ; Mutagenesis, Site-Directed ; Mutation ; Plasmids/genetics* ; Polymerase Chain Reaction/methods*

Epidermal growth factor receptor (EGFR) exon 20 insertion mutations are the third most prevalent activating EGFR mutation in non-small cell lung cancer (NSCLC), accounting for 5%-12% of all EGFR mutations in NSCLC cases. Patients harboring EGFR exon 20 insertion mutations exhibit similar clinical characteristics except for worse prognosis as compared to those with 'classic' EGFR mutations. EGFR exon 20 insertion mutations are considered as a heterogeneous class of alterations that cause different conformational changes in EGFR. The majority of mutations (almost 90% of cases) is positioned in the loop that immediately follows the C-terminal of the C-helix, and the most widely reported subtype of insertion mutations is D770_N771>ASVDN(A767_V769dupASV) with frequency of 21%-28%. NSCLC patients with EGFR exon 20 insertion mutations show primary drug resistance to previously approved EGFR tyrosine kinase inhibitors and are generally insensitive to conventional chemotherapy and immunotherapy. The recently approved targeted drugs Amivantamab and Mobocertinib shift the treatment paradigm for NSCLC patients harboring EGFR exon 20 insertion mutations. There are also several new compounds targeting NSCLC EGFR exon 20 insertion mutations are in development. In this article, we provide a through overview on the treatment development in EGFR exon 20 insertion mutant NSCLC.
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Antibodies, Bispecific ; Carcinoma, Non-Small-Cell Lung/genetics* ; ErbB Receptors/genetics* ; Exons ; Humans ; Lung Neoplasms/genetics* ; Mutagenesis, Insertional ; Mutation ; Protein Kinase Inhibitors/therapeutic use*

Creatinine levels in biological fluids are important indicators for the clinical evaluation of renal function. Creatinase (CRE, EC3.5.3.3) is one of the key enzymes in the enzymatic measurement of creatinine concentration, and it is also the rate-limiting enzyme in the whole enzymatic cascade system. The poor catalytic activity of CRE severely limits its clinical and industrial applications. To address this issue, a semi-rational design is applied to increase the activity of a creatinase from Alcaligenes sp. KS-85 (Al-CRE). By high-throughput screen of saturation mutagenesis libraries on the selected hotspot mutations, multiple variant enzymes with increased activity are obtained. The five-point best variant enzyme (I304L/F395V/K351V/Y63S/Q88A) were further obtained by recombine the improved mutations sites that to showed a 2.18-fold increased specific activity. Additionally, structure analysis is conducted to understand the mechanism of the activity change. This study paves the way for a better practical application of creatinase and may help further understand its catalytic mechanism.
Creatinine ; Mutagenesis, Site-Directed ; Ureohydrolases/genetics* ; Catalysis