Holliday junction-resolving enzymes have been identified in a broad variety of organisms and tissues. In this study, six new Holliday junction-cleaving enzymes (Hjcs) were obtained from hyperthermophilic crenarchaeal and euryarchaeal species, including Pyrococcus horikoshii, Pyrococcus abyssi, Methanococcus jannaschii, Methanobacterium thermautotrophicum, Archaeoglobus fulgidus, and Aeropyrum pernix. The genes were cloned and overexpressed in Escherichia coli, and the respective proteins were purified from crude extracts to homogeneity. For an initial characterization of the enzymatic activities, synthetic heat-stable fixed and mobile cruciform DNA substrates were used at 75 degrees C. The Hjcs from Pyrococcus furiosus, Sulfolobus solfataricus, and the archaeal virus SIRV2 were included in the study for comparison. Despite their sequence homology, the enzymes showed marked differences in their reactions with individual cruciform DNAs. While the fixed cruciform structure was cleaved by all enzymes at only one major position, the mobile cruciform structure displayed different cleavage patterns for individual Hjcs, each with several cleavage positions. Furthermore, a strong bias for cleavage of one direction across the junction was observed with the fixed cruciform DNA for all enzymes. In contrast, the mobile cruciform DNA displayed different preferences, depending on the enzyme used.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1007/s00792-002-0265-8 | DOI Listing |
iScience
December 2024
Guangzhou Municipal Key Laboratory of Metabolic Diseases and Reproductive Health, The Affiliated Guangdong Second Provincial General Hospital of Jinan University, Guangzhou, China.
AT-rich sequence can cause structure variants such as translocations and its instability can be accelerated by replication stresses. When human 16p11.2 or 22q11.
View Article and Find Full Text PDFNucleic Acids Res
December 2024
Department of Biology, Tufts University, Suite 4700, 200 Boston Ave, Medford, MA 02155, USA.
Long AT repeat tracts form non-B DNA structures that stall DNA replication and cause chromosomal breakage. AT repeats are abundant in human common fragile sites (CFSs), genomic regions that undergo breakage under replication stress. Using an in vivo yeast model system containing AT-rich repetitive elements from human CFS FRA16D, we find that DNA polymerase zeta (Pol ζ) is required to prevent breakage and subsequent deletions at hairpin and cruciform forming (AT/TA)n sequences, with little to no role at an (A/T)28 repeat or a control non-structure forming sequence.
View Article and Find Full Text PDFSoft Matter
December 2024
Department of Applied Chemistry, School of Chemistry and Chemical Engineering, Yantai University, Yantai 264006, China.
RSC Adv
November 2024
Institute of Physics, Faculty of Mathematics and Physics, Charles University Ke Karlovu 5, 121 16 Prague 2 Czech Republic +420 95155 1471.
Recently published observations have highlighted the presence of cruciform structures within the genome, suggesting their potential significance in the rapid recognition of the target sequence for transcription factor binding. In this study, we investigate the organization and stability of the (coding) strand within the Serum Response Element of the gene promoter ( SRE), specifically focusing on segments spanning 12 to 36 nucleotides, centered around the CArG-box. Through a thorough examination of UV absorption patterns with varying temperatures, we identified the emergence of a remarkably stable structure, which we conclusively characterized as a hairpin using complementary H NMR experiments.
View Article and Find Full Text PDFGenomics Inform
November 2024
Department of Biotechnology, Koneru Lakshmaiah Education Foundation, Vaddeswaram, Guntur, Andhra Pradesh, 522302, India.
The untranslated regions (UTRs) of genes significantly impact various biological processes, including transcription, posttranscriptional control, mRNA stability, localization, and translation efficiency. In functional areas of genomes, non-B DNA structures such as cruciform, curved, triplex, G-quadruplex, and Z-DNA structures are common and have an impact on cellular physiology. Although the role of these structures in cis-regulatory regions such as promoters is well established in eukaryotic genomes, their prevalence within UTRs across different eukaryotic classes has not been extensively documented.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!