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The structural diversity of biological macromolecules in different environments contributes complexity to enzymological processes vital for cellular functions. Fluorescence resonance energy transfer and electron microscopy are used to investigate the enzymatic reaction of T4 DNA ligase catalyzing the ligation of nicked DNA. The data show that both the ligase-AMP complex and the ligase-AMP-DNA complex can have four conformations. This finding suggests the parallel occurrence of four ligation reaction pathways, each characterized by specific conformations of the ligase-AMP complex that persist in the ligase-AMP-DNA complex. Notably, these complexes have DNA bending angles of ≈0°, 20°, 60°, or 100°. The mechanism of parallel reactions challenges the conventional notion of simple sequential reaction steps occurring among multiple conformations. The results provide insights into the dynamic conformational changes and the versatile attributes of T4 DNA ligase and suggest that the parallel multiple reaction pathways may correspond to diverse T4 DNA ligase functions. This mechanism may potentially have evolved as an adaptive strategy across evolutionary history to navigate complex environments.

The RecQ family of helicases are important for maintenance of genomic integrity. Although functions of constructive subdomains of this family of helicases have been extensively studied, the helical hairpin (HH) in the RecQ-C-terminal domain (RQC) has been underappreciated and remains poorly understood. Here by using single-molecule fluorescence resonance energy transfer, we found that HH in the human BLM transiently intercepts different numbers of nucleotides when it is unwinding a double-stranded DNA. Single-site mutations in HH that disrupt hydrogen bonds and/or salt bridges between DNA and HH change the DNA binding conformations and the unwinding features significantly. Our results, together with recent clinical tests that correlate single-site mutations in HH of human BLM with the phenotype of cancer-predisposing syndrome or Bloom's syndrome, implicate pivotal roles of HH in BLM's DNA unwinding activity. Similar mechanisms might also apply to other RecQ family helicases, calling for more attention to the RQC helical hairpin.

Objective To investigate the clinical effect of transanal tube drainage and anal decompression after endoscopic submucosal dissection (ESD) of giant colorectal polyp for postoperative recovery and the prevention of complication. Methods Prospective clinical randomized control study was done. Enrolled patients with giant colorectal polyps (diameter ≥3 cm) were divided into 100 cases in endoscopic treatment group(endoscopic group) and 92 cases in endoscopic treatment with prophylactic anal tube implantation group (endoscopic anal tube group). Postoperative recovery and complication between 2 groups were compared. Results Delay bleeding from anal of postoperative complications was present 5(5.0%) cases in endoscopic group and 2(2.2%) cases in endoscopic anal tube group. There were electrocoagulation syndrome of complications 7 (7.0%) cases in endoscopic group and 1(1.1%) case in endoscopic anal tube group. The difference in postoperative complication rate was significant statistically(P0.05) between two groups. Intestinal peristalsis returned (22.5±5.9) h after operation in endoscopic anal tube group and (39.3±10.4) h in endoscopic group with statistically significant differences (P

Effective management of laboratory biosafety plays one of the most important roles in the national biosafety system. Laboratory animals have been widely used in the life science research field, including infection animal experiments, which have to be done in the animal biosafety laboratory (ABSL). The risk assessment and control related to laboratory animals and animal experiments are the most important affairs in ABSL, and the identification and traceability of laboratory animals detected by wireless tracking technology represent a developing tendency in ABSL management. From the perspective of biosafety, this paper summarized the development of laboratory animal identification and traceability technology,and described the application prospect in ABSL management of non-contact identification technology, especially radio frequency identification technology, which can provide reference for relevant practitioners to use the identification and traceability technology of experimental animals for biosafety control.

Protein surfaces have pivotal roles in interactions between proteins and other biological molecules. However, the structural dynamics of protein surfaces have rarely been explored and are poorly understood. Here, the surface of a single‐stranded DNA (ssDNA) binding protein (SSB) with four DNA binding domains that bind ssDNA in binding site sizes of 35, 56, and 65 nucleotides per tetramer is investigated. Using oligonucleotides as probes to sense the charged surface, NaCl induces a two‐state structural transition on the SSB surface even at moderate concentrations. Chelation of sodium ions with charged amino acids alters the network of hydrogen bonds and/or salt bridges on the surface. Such changes are associated with changes in the electrostatic potential landscape and interaction mode. These findings advance the understanding of the molecular mechanism underlying the enigmatic salt‐induced transitions between different DNA binding site sizes of SSBs. This work demonstrates that monovalent salt is a key regulator of biomolecular interactions that not only play roles in non‐specific electrostatic screening effects as usually assumed but also may configure the surface of proteins to contribute to the effective regulation of biomolecular recognition and other downstream events. [ABSTRACT FROM AUTHOR]

Transmembrane protein 52B (TMEM52B), a newly identified tumor‐related gene, has been reported to regulate various tumors, yet its role in nasopharyngeal carcinoma (NPC) remains unclear. Transcriptomic analysis of NPC cell lines reveals frequent overexpression of TMEM52B, and immunohistochemical results show that TMEM52B is associated with advanced tumor stage, recurrence, and decreased survival time. Depleting TMEM52B inhibits the proliferation, migration, invasion, and oncogenesis of NPC cells in vivo. TMEM52B encodes two isoforms, TMEM52B‐P18 and TMEM52B‐P20, differing in their N‐terminals. While both isoforms exhibit similar pro‐oncogenic roles and contribute to drug resistance in NPC, TMEM52B‐P20 differentially promotes metastasis. This functional discrepancy may be attributed to their distinct subcellular localization; TMEM52B‐P18 is confined to the cytoplasm, while TMEM52B‐P20 is found both at the cell membrane and in the cytoplasm. Mechanistically, cytoplasmic TMEM52B enhances AKT phosphorylation by interacting with phosphoglycerate kinase 1 (PGK1), fostering NPC growth and metastasis. Meanwhile, membrane‐localized TMEM52B‐P20 promotes E‐cadherin ubiquitination and degradation by facilitating its interaction with the E3 ubiquitin ligase NEDD4, further driving NPC metastasis. In conclusion, the TMEM52B‐P18 and TMEM52B‐P20 isoforms promote the metastasis of NPC cells through different mechanisms. Drugs targeting these TMEM52B isoforms may offer therapeutic benefits to cancer patients with varying degrees of metastasis. [ABSTRACT FROM AUTHOR]

Objective: Finding biomarkers related to non-small cell lung cancer (NSCLC) is helpful for the diagnosis and precise treatment of lung cancer. The relationship between serum tumor M2-pyruvate kinase (TuM2-PK), carcinoembryonic antigen (CEA), and cytokeratin 19 fragment (CYFRA21-1) and NSCLC was analyzed. Methods: The serum levels of TuM2-PK, CEA, and CYFRA21-1 in 184 patients with the NSCLC group, 60 patients with the benign lung disease (BLD) group, and 90 healthy controls (HC) group were detected. The levels of TuM2-PK were measured by using an enzyme-linked immunosorbent assay. The detection methods of CEA and CYFRA21-1 were electrochemiluminescence. The receiver operating characteristic (ROC) curve was drawn to evaluate the diagnostic value of TuM2-PK, CEA, and CYFRA21-1 on NSCLC. The Kaplan–Meier survival curve was drawn to evaluate the survival status in NSCLC patients with different serum levels of TuM2-PK, CEA, and CYFRA21-1. Results: Serum levels of TuM2-PK, CEA, and CYFRA21-1 in the NSCLC group were significantly higher than those in the BLD group and the HC group (P <.01). Serum levels of TuM2-PK, CEA, and CYFRA21-1 in NSCLC patients were associated with the tumor lymph node metastasis stage (P <.05), lymph node metastasis (P <.05), and distant metastasis (P <.05). The ROC curve showed that the area under the curve of serum levels of TuM2-PK, CEA, and CYFRA21-1 was 0.814, 0.638, and 0.719, respectively, and that the combination of the above 3 was 0.918. The Kaplan–Meier survival curve showed that the 1-, 3- and 5-year survival rate in NSCLC patients with positive TuM2-PK, CEA, and CYFRA21-1 was significantly lower than that in NSCLC patients with negative TuM2-PK, CEA, and CYFRA21-1, respectively (P <.05). Conclusions: Serum TuM2-PK, CEA, and CYFRA21-1 levels have high clinical values in the diagnosis of NSCLC, and can effectively judge the prognosis of patients. [ABSTRACT FROM AUTHOR]

Objective Exploring the relationship between changes in serum Golgi apparatus transmembrane glycoprotein 73 (GP73) and chitosanase 3-like protein 1 (CHI3L1) levels and liver fibrosis and lesion severity in patients with hepatitis B (CHB). Methods Using a case-control study, 80 patients diagnosed with CHB infection and developing liver fibrosis in the Infectious Disease Department of Changsha First Hospital from June 2020 to June 2023 were selected as the liver fibrosis group, while 120 patients diagnosed with CHB infection but not developing liver fibrosis in the Infectious Disease Department of our hospital were selected as the control group. The serum GP3, CHI3L1, liver function, and fibrosis indicators of the two groups of patients were compared, and the liver fibrosis group was divided into mild according to Scheuer system standards Perform stratified analysis on patients with significant liver fibrosis. Results The serum GP3 and CHI3L1 levels in the liver fibrosis group were significantly higher than those in the control group, with statistical significance (P < 0.05); The ROC curves were plotted using serum GP3, CHI3L1, and GP3 + CHI3L1, respectively. The sensitivity for diagnosing liver fibrosis in CHB patients was 62.81%, 60.94%, and 96.33%, with specificity of 80.66%, 80.05%, and 75.30%. The AUC values under the curves were 0.792, 0.756, and 0.908, respectively; The levels of ALT, AST, HA, LN, PC III NP, C IV, and CG in the liver fibrosis group were higher than those in the control group, and the PLT measurement values were lower than those in the control group, with statistical significance (P < 0.05) ; 49 patients with moderate to severe liver fibrosis (33 in S2 phase and 16 in S3 phase) and 31 patients with mild liver fibrosis (all in S1 phase) had significantly higher serum GP3 and CHI3L1 levels than mild patients, with statistical significance (P < 0.05; The levels of DBIL, ALT, AST, HA, LN, PC III NP, C IV, and CG in patients with moderate to severe liver fibrosis were higher than those in the mild group, and the PLT measurement values were lower than those in the mild group, with statistical significance (P < 0.05). Conclusion The serum GP3 and CHI3L1 levels in CHB patients with liver fibrosis are significantly elevated, and there is a certain correlation with the degree of liver fibrosis. The combination of these two indicators is beneficial for diagnosing liver fibrosis in CHB patients. [ABSTRACT FROM AUTHOR]