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)

The phage T7 endonuclease gene was fused to the 3' end of the lac repressor gene. The hybrid protein exhibits repressor and nuclease functions in a manner dependent on the conformation of the DNA. With supercoiled DNA, nuclease activity is directed to the major cruciform, whereas with linear DNA, the enzyme cleaves preferentially restriction fragments carrying the operator. These properties render the hybrid protein a unique probe of DNA conformation in vitro and in vivo.
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PMID:Biosynthesis of a repressor/nuclease hybrid protein. 276 53

We have isolated the structural gene, PRB1, for the vacuolar protease B of Saccharomyces cerevisiae from a genomic library by complementation of the prb1-1122 mutation. Deletion analysis localized the complementing activity to a 3.2-kilobase pair XhoI-HindIII restriction enzyme fragment. The fragment was used to identify a 2.3-kilobase mRNA. S1 endonuclease mapping indicated that the mRNA and the gene were colinear. No introns were detected. The mRNA is of sufficient size to encode a protein of about 69,000 molecular weight, a number much larger than either the mature enzyme (congruent to 30,000 protein molecular weight) or the sole reported precursor (congruent to 39,000 protein molecular weight). These results suggest that proteolytic processing steps beyond that thought to be catalyzed by protease A may be required to convert the initial glycosylated translation product into mature protease B. The PRB1 mRNA is made in substantial amounts only when the cells have exhausted the glucose supply and enter the diauxic plateau. There is an extended time lag between PRB1 transcription and expression of protease B activity. A deletion that removes about 83% of the coding region was constructed as a diploid heterozygote. Spores bearing the deletion germinate, grow at normal rates into colonies, and have no obvious phenotype beyond protease B deficiency.
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PMID:Protease B of Saccharomyces cerevisiae: isolation and regulation of the PRB1 structural gene. 354 51

A tripartite fusion construct encoding the amino-terminal half of EcoRI endonuclease followed by amino acids 217-299 of the filamentous bacteriophage gene I protein (pI) attached to the enzymatic portion of alkaline phosphatase results in the production of two proteins. The larger protein, pIf, is the complete tripartite fusion protein while the smaller protein, pIf*, results from internal initiation of translation at pI methionine 241. Both pIf and pIf* span the Escherichia coli inner membrane via a 20-amino-acid hydrophobic stretch of pI with their amino termini in the cytoplasm and their carboxyl-terminal alkaline phosphatase domains in the periplasm. The alkaline phosphatase moiety of approximately 70% of pIf is released into the periplasm by in vivo proteolysis, but only about 10% of pIf* is cleaved. Neither DegP, OmpT, nor protease III are responsible for the cleavage in vivo, and leader peptidase is unable to cleave the fusion protein in vitro. Deletion and substitution analyses demonstrate that the degree of periplasmic cleavage depends on the sequence of the cytoplasmic domain of the fusion proteins. Possible mechanisms for this transmembrane-directed cleavage event are compared to proposed models for signal transduction.
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PMID:The membrane domain of a bacteriophage assembly protein. Transmembrane-directed proteolysis of a membrane-spanning fusion protein. 844 11

The endonuclease colicin E2 (ColE2), a bacteriocidal protein, and the associated cognate immunity protein (Im2) are released from producing Escherichia coli cells. ColE2 interaction with the target cell outer membrane BtuB protein and Tol import machinery allows the dissociation of Im2 from its colicin at the outer membrane surface. Here, we use in vivo approaches to show that a small amount of ColE2-Im2 protein complex bound to sensitive cells is susceptible to proteolytic cleavage by the outer membrane protease, OmpT. The presence of BtuB is required for ColE-Im2 cleavage by OmpT. The amount of colicin cleaved by OmpT is greatly enhanced when ColE2 is dissociated from Im2. We further demonstrate that OmpT cleaves the C-terminal DNase domain of the toxin. As expected, strains that over-produce OmpT are less susceptible to infection by ColE2 than by ColE2-Im2. Our findings reveal an additional function for the immunity protein beside protection of producing cells against their own colicin in the cytoplasm. Im2 protects ColE2 against OmpT-mediated proteolytic attack.
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PMID:Immunity protein protects colicin E2 from OmpT protease. 1899 Jul 18