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The plastid DNA (ptDNA) replication is initiated by primases, which synthesize RNA primers; following the synthesis of DNA fragments, primers must be removed before ligation. However, the enzymes and mechanisms underlying this process are poorly understood. Here we cloned a gene from maize that encodes a plastid-localized and Mn-dependent 5'-3' exonuclease (designated PEN1) responsible for this process. The pen1 seeds show development and filling defects that intensify across generations. PEN1 cleaves the RNA primers, allowing for the complete excision of ribonucleotides. We reconstituted the plastid RNA primer removal processes in vitro. We also determined the crystal structure of the PEN1-dsDNA binary complex and explained the structural mechanism of the 5' to 3' exonuclease activity. Mutation of Pen1 resulted in the accumulation of ptDNA breaks, thereby compromising plastid function. These studies fill a critical gap that has long existed in the understanding of ptDNA replication.
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http://dx.doi.org/10.1038/s41477-025-02027-4 | DOI Listing |
Microb Genom
September 2025
Department of Infection Biology, Faculty of Infectious and Tropical Diseases, London School of Hygiene & Tropical Medicine, London, UK.
Amplicon sequencing is a popular method for understanding the diversity of bacterial communities in samples containing multiple organisms as exemplified by 16S rRNA sequencing. Another application of amplicon sequencing includes multiplexing both primer sets and samples, allowing sequencing of multiple targets in multiple samples in the same sequencing run. Multiple tools exist to process the amplicon sequencing data produced via the short-read Illumina platform, but there are fewer options for long-read Oxford Nanopore Technologies (ONT) sequencing, or for processing data from environmental surveillance or other sources with many different organisms.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
September 2025
HHMI and The Rockefeller University, New York, NY 10065.
Replication of cellular chromosomes requires a primase to generate short RNA primers to initiate genomic replication. While bacterial and archaeal primase generate short RNA primers, the eukaryotic primase, Polα-primase, contains both RNA primase and DNA polymerase (Pol) subunits that function together to form a >20 base hybrid RNA-DNA primer. Interestingly, the DNA Pol1 subunit of Polα lacks a 3'-5' proofreading exonuclease, contrary to the high-fidelity normally associated with DNA replication.
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 PDFFront Cell Infect Microbiol
September 2025
State Key Laboratory for Animal Disease Control and Prevention, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
Strangles, a highly contagious disease caused by subspecies (), significantly impacts horse populations worldwide, with Iceland as the only exception. This disease poses serious threats to equine health and results in considerable economic losses. Consequently, the accurate, sensitive, and rapid detection of from clinical samples is essential for early warning and effective disease management.
View Article and Find Full Text PDFbioRxiv
August 2025
Howard Hughes Medical Institute, Department of Chemistry, The University of Chicago, Chicago, IL 60637, USA.
The composition of the primordial genetic material remains uncertain. Studies of duplex structure and stability, and of nonenzymatic template copying chemistry, provide insight into the viability of potentially primordial genetic polymers. Recent work suggests that 2'-deoxyribo-purine nucleotides may have been generated together with ribonucleotides on the early Earth.
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