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Biologically functional DNA hairpins are found in archaea, prokaryotes and eukaryotes, playing essential roles in various DNA transactions. However, during DNA replication, hairpin formation can stall the polymerase and is therefore prevented by the single-stranded DNA binding protein (SSB). Here, we address the question how hairpins maintain their functional secondary structure despite SSB's presence. As a model hairpin, we used the recombinogenic form of the attC site, essential for capturing antibiotic-resistance genes in the integrons of bacteria. We found that attC hairpins have a conserved high GC-content near their apical loop that creates a dynamic equilibrium between attC fully opened by SSB and a partially structured attC-6-SSB complex. This complex is recognized by the recombinase IntI, which extrudes the hairpin upon binding while displacing SSB. We anticipate that this intriguing regulation mechanism using a base pair distribution to balance hairpin structure formation and genetic stability is key to the dissemination of antibiotic resistance genes among bacteria and might be conserved among other functional hairpins.
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http://dx.doi.org/10.1093/nar/gkx670 | DOI Listing |
Anal Chem
September 2025
Jiaxing Key Laboratory of Molecular Recognition and Sensing, College of Biological and Chemical Engineering, Jiaxing University, Jiaxing 314001, China.
Despite the promise of electrochemical biosensors in amplified nucleic acid diagnostics, existing high-sensitivity platforms often rely on a multilayer surface assembly and cascade amplification confined to the electrode interface. These stepwise strategies suffer from inefficient enzyme activity, poor mass transport, and inconsistent probe orientation, which compromise the amplification efficiency, reproducibility, and practical applicability. To address these limitations, we report a programmable dual-phase electrochemical biosensing system that decouples amplification from signal transduction.
View Article and Find Full Text PDFAnal Chem
September 2025
State Key Laboratory of Physical Chemistry of Solid Surfaces, College of Chemistry and Chemical Engineering, College of Energy, Discipline of Intelligent Instrument and Equipment, State Key Laboratory of Vaccines for Infectious Diseases, Xiang An Biomedicine Laboratory, Xiamen University, Xiamen 361
Rolling circle amplification (RCA) has revolutionized nucleic acid detection owing to its isothermal simplicity. However, over two decades of clinical application have been hampered by off-target amplification and incompatibility with double-stranded DNA (dsDNA). Herein, a strategy, specifically cleavage of rationally designed DNA/RNA chimeric hairpin preprimer by dsDNA-targeted CRISPR/Cas12a to rlease ssRNA for initiating RCA (SCOPE-RCA), is proposed for nucleic acid identification of African swine fever virus (ASFV).
View Article and Find Full Text PDFNucleic Acids Res
September 2025
Key Laboratory of Clinical Laboratory Diagnostics (Chinese Ministry of Education), College of Laboratory Medicine, Chongqing Medical University, Chongqing 400016, P. R. China.
Local pH variations play a pivotal role in numerous critical biological processes. However, achieving the tunability and selectivity of pH detection remains a challenge. Here, we present a DNA-based strategy that enables programmable and selective pH responses, which is termed shadow-strand hybridization-actuated displacement engineering (SHADE).
View Article and Find Full Text PDFAnal Chem
September 2025
College of Natural Resources and Environment, South China Agricultural University, Guangzhou 510642, China.
A series of molecular logic gates with multiple biocomputing capabilities have been successfully fabricated by using four antibiotic residues [tetracycline (TET), chloramphenicol (CHL), kanamycin (KAN), and streptomycin (STR)] as inputs. The lateral flow strip biosensor was utilized to realize the visual and portable sensing of logic events. Four basic logic gates (OR, AND, XOR, and INHIBIT) and three cascade logic circuits (OR-INHIBIT-AND, 3AND-OR, and XOR-INHIBIT-OR-AND) were constructed.
View Article and Find Full Text PDFBiosens Bioelectron
September 2025
College of Chemistry, Jilin Province Research Center for Engineering and Technology of Spectral Analytical Instruments, Jilin University, Qianjin Street 2699, Changchun, 130012, China. Electronic address:
Papillary thyroid carcinoma (PTC) is the most prevalent form of thyroid cancer with a high incidence among endocrine malignancies. It tends to metastasize early in lymph nodes and differs markedly from other subtypes in biological behavior, clinical management, and prognosis. Therefore, accurately distinguishing PTC from other pathological subtypes is crucial for guiding diagnosis and treatment decisions.
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