Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.30.2 (endonuclease)
 18,621 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have isolated five genomic clones for human butyrylcholinesterase (BChE), using cDNA probes encoding the catalytic subunit of the hydrophilic tetramer [McTiernan et al. (1987) Proc. Natl. Acad. Sci. U.S.A. 84, 6682-6686]. The BChE gene is at least 73 kb long and contains four exons. Exon 1 contains untranslated sequences and two potential translation initiation sites at codons -69 and -47. Exon 2 (1525 bp) contains 83% of the coding sequence for the mature protein, including the N-terminal and the active-site serine, and a third possible translation initiation site (likely functional), at codon -28. Exon 3 is 167 nucleotides long. Exon 4 (604 bp) codes for the C-terminus of the protein and the 3' untranslated region where two polyadenylation signals were identified. Intron 1 is 6.5 kb long, and the minimal sizes of introns 2 and 3 are estimated to be 32 kb each. Southern blot analysis of total human genomic DNA is in complete agreement with the gene structure established by restriction endonuclease mapping of the genomic clones: this strongly suggests that the BChE gene is present in a single copy.
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PMID:Structure of the gene for human butyrylcholinesterase. Evidence for a single copy. 232 35

The trypanosomatid protozoan Trypanosoma cruzi contains long autonomous (L1Tc) and short nonautonomous (NARTc) non-long terminal repeat retrotransposons. NARTc (0.25 kb) probably derived from L1Tc (4.9 kb) by 3'-deletion. It has been proposed that their apparent random distribution in the genome is related to the L1Tc-encoded apurinic/apyrimidinic endonuclease (APE) activity, which repairs modified residues. To address this question we used the T. cruzi (CL-Brener strain) genome data to analyze the distribution of all the L1Tc/NARTc elements present in contigs larger than 10 kb. This data set, which represents 0.91x sequence coverage of the haploid nuclear genome ( approximately 55 Mb), contains 419 elements, including 112 full-length L1Tc elements (14 of which are potentially functional) and 84 full-length NARTc. Approximately half of the full-length elements are flanked by a target site duplication, most of them (87%) are 12 bp long. Statistical analyses of sequences flanking the full-length elements show the same highly conserved pattern upstream of both the L1Tc and NARTc retrotransposons. The two most conserved residues are a guanine and an adenine, which flank the site where first-strand cleavage is performed by the element-encoded endonuclease activity. This analysis clearly indicates that the L1Tc and NARTc elements display relative site specificity for insertion, which suggests that the APE activity is not responsible for first-strand cleavage of the target site.
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PMID:The Trypanosoma cruzi L1Tc and NARTc non-LTR retrotransposons show relative site specificity for insertion. 1626 42

The nucleotide excision repair mechanism (NER) of Escherichia coli is responsible for the recognition and elimination of more than twenty different DNA lesions. Herein, we evaluated the in vivo role of NER in the repair of DNA adducts generated by psoralens (mono- or bi-functional) and UV-A light (PUVA) in E. coli. Cultures of wild-type E. coli K12 and mutants for uvrA, uvrB, uvrC or uvrAC genes were treated with PUVA and cell survival was determined. In parallel, kinetics of DNA repair was also evaluated by the comparison of DNA sedimentation profiles in all the strains after PUVA treatment. The uvrB mutant was more sensitive to PUVA treatment than all the other uvr mutant strains. Wild-type strain, and uvrA and uvrC mutants were able to repair PUVA-induced lesions, as seen by DNA sedimentation profiles, while the uvrB mutant was unable to repair the lesions. In addition, a quadruple fpg nth xth nfo mutant was unable to nick PUVA-treated DNA when the crude cell-free extract was used to perform plasmid nicking. These data suggest that DNA repair of PUVA-induced lesions may require base excision repair functions, despite proficient UvrABC activity. These results point to a specific role for UvrB protein in the repair of psoralen adducts, which appear to be independent of UvrA or UvrC proteins, as described for the classical UvrABC endonuclease mechanism.
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PMID:Differential survival of Escherichia coli uvrA, uvrB, and uvrC mutants to psoralen plus UV-A (PUVA): Evidence for uncoupled action of nucleotide excision repair to process DNA adducts. 2000 8

The CRISPR-Cas13b system is a recently identified Class 2, RNA-targeting CRISPR-Cas system. The system has been repurposed to achieve robust mRNA knockdown and precise RNA-editing in mammalian cells. While the CRISPR-Cas13b system has become a powerful tool for nucleic acids manipulation, the mechanisms of the system are still not fully understood. Cas13b endonucleases from different bacterial species show poor overall sequence homologies, suggesting that structural (and probably functional) diversities may exist. It is therefore important to study CRISPR-Cas13b cases from different bacterial species. Here we report the expression, purification, and initial characterization of a Cas13b endonuclease that is associated with the 8th putative CRISPR locus from Porphyromonas gingivalis genome (Pgi8Cas13b). The full-length Pgi8Cas13b protein (1119 residues) was successfully expressed in E. Coli cells, and purified by affinity and ion-exchange chromatography methods. The purified protein is biologically active, being able to bind its cognate crRNA with high specificity and affinity. Preparation of biologically active Pgi8Cas13b protein provides the basis for further in vitro biochemical and biophysical studies of the Pgi8Cas13b CRISPR system.
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PMID:Bacterial expression, purification, and initial characterization of a full-length Cas13b protein from Porphyromonas gingivalis. 3200 55