DNA replication stress threatens ordinary DNA synthesis. The evolutionarily conserved DNA replication stress response pathway involves sensor kinase Mec1/ATR, adaptor protein Mrc1/Claspin, and effector kinase Rad53/Chk1, which spurs a host of changes to stabilize replication forks and maintain genome integrity. DNA replication forks consist of largely distinct sets of proteins at leading and lagging strands that function autonomously in DNA synthesis in vitro. In this article, we discuss eSPAN and BrdU-IP-ssSeq, strand-specific sequencing technologies that permit analysis of protein localization and DNA synthesis at individual strands in budding yeast. Using these approaches, we show that under replication stress Rad53 stalls DNA synthesis on both leading and lagging strands. On lagging strands, it stimulates PCNA unloading, and on leading strands, it attenuates the replication function of Mrc1-Tof1. We propose that in doing so, Rad53 couples leading and lagging strand DNA synthesis during replication stress, thereby preventing the emergence of harmful ssDNA.
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http://dx.doi.org/10.1002/bies.202200061 | DOI Listing |
Nat Struct Mol Biol
January 2025
Laboratory of Molecular Biophysics, The Rockefeller University, New York, NY, USA.
Following transcript release during intrinsic termination, Escherichia coli RNA polymerase (RNAP) often remains associated with DNA in a post-termination complex (PTC). RNAPs in PTCs are removed from the DNA by the SWI2/SNF2 adenosine triphosphatase (ATPase) RapA. Here we determined PTC structures on negatively supercoiled DNA and with RapA engaged to dislodge the PTC.
View Article and Find Full Text PDFNature
January 2025
Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA, USA.
Diversity-generating retroelements (DGRs) create massive protein sequence variation (up to 10) in ecologically diverse microorganisms. A recent survey identified around 31,000 DGRs from more than 1,500 bacterial and archaeal genera, constituting more than 90 environment types. DGRs are especially enriched in the human gut microbiome and nano-sized microorganisms that seem to comprise most microbial life and maintain DGRs despite reduced genomes.
View Article and Find Full Text PDFNature
January 2025
Stanford Cancer Institute, School of Medicine, Stanford University, Stanford, CA, USA.
Breast cancer is a highly heterogeneous disease whose prognosis and treatment as defined by the expression of three receptors-oestrogen receptor (ER), progesterone receptor and human epidermal growth factor receptor 2 (HER2; encoded by ERBB2)-is insufficient to capture the full spectrum of clinical outcomes and therapeutic vulnerabilities. Previously, we demonstrated that transcriptional and genomic profiles define eleven integrative subtypes with distinct clinical outcomes, including four ER subtypes with increased risk of relapse decades after diagnosis. Here, to determine whether these subtypes reflect distinct evolutionary histories, interactions with the immune system and pathway dependencies, we established a meta-cohort of 1,828 breast tumours spanning pre-invasive, primary invasive and metastatic disease with whole-genome and transcriptome sequencing.
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January 2025
Centre for Genomic Regulation (CRG), The Barcelona Institute of Science and Technology, Barcelona, Spain.
Missense variants that change the amino acid sequences of proteins cause one-third of human genetic diseases. Tens of millions of missense variants exist in the current human population, and the vast majority of these have unknown functional consequences. Here we present a large-scale experimental analysis of human missense variants across many different proteins.
View Article and Find Full Text PDFSci Rep
January 2025
Botany and Microbiology Department, Faculty of Science, Al-Azhar University (Girl Branch), Cairo, Egypt.
Biosynthesized nanoparticles have a variety of applications, and microorganisms are considered one of the most ideal sources for the synthesis of green nanoparticles. Icerya aegyptiaca (Douglas) is a pest that has many generations per year and can affect 123 plant species from 49 families by absorbing sap from bark, forming honeydew, causing sooty mold, and attracting invasive ant species, leading to significant agricultural losses. The purpose of this work was to synthesize titanium dioxide nanoparticles (TiO-NPs) from marine actinobacteria and evaluate their insecticidal effects on Icerya aegyptiaca (Hemiptera: Monophlebidae), in addition to explaining their effects on protein electrophoresis analysis of SDS‒PAGE proteins from control and treated insects after 24, 72 and 120 h of exposure.
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