Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.2.1.23 (beta-galactosidase)
 14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Proteus mirabilis, a common agent of nosocomially acquired and catheter-associated urinary tract infection, is the most frequent cause of infection-induced bladder and kidney stones. Urease-catalyzed urea hydrolysis initiates stone formation in urine and can be inhibited by acetohydroxamic acid and other structural analogs of urea. Since P. mirabilis urease is inducible with urea, there has been some concern that urease inhibitors actually induce urease during an active infection, thus compounding the problem of elevated enzyme activity. Quantitating induction by compounds that simultaneously inhibit urease activity has been difficult. Therefore, to study these problems, we constructed a fusion of ureA (a urease subunit gene) and lacZ (the beta-galactosidase gene) within plasmid pMID1010, which encodes an inducible urease of P. mirabilis expressed in E. coli JM103 (Lac-). The fusion protein, predicted to be 117 kDa, was induced by urea and detected on Western blots (immunoblots) with anti-beta-galactosidase antiserum. Peak beta-galactosidase activity of 9.9 mumol of ONPG (o-nitrophenyl-beta-D-galactopyranoside) hydrolyzed per min per mg of protein, quantitated spectrophotometrically, was induced at 200 mM urea. The uninduced rate was 0.2 mumol of ONPG hydrolyzed per min per mg of protein. Induction was specific for urea, as no structural analog of urea (including acetohydroxamic acid, hydroxyurea, thiourea, hippuric acid, flurofamide, or hydroxylamine) induced fusion protein activity. These data suggest that induction by inactivation of UreR, the urease repressor protein that governs regulation of the urease operon, is specific for urea and does not respond to closely related structural analogs.
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PMID:Proteus mirabilis urease: use of a ureA-lacZ fusion demonstrates that induction is highly specific for urea. 189 50

Multiple lines of evidence show that oxidation products of ascorbic acid (vitamin C) are capable of inducing a variety of genetic alterations in microbial and mammalian cells. We have studied the inactivation kinetics in repair proficient and deficient Escherichia coli K12 cells treated with oxidized solutions of ascorbic acid, in the presence of catalytic amounts of copper. Our results suggest that the repair pathways controlled by the recA and uvrA gene products (the latter in a recA strain) contribute to cell survival. However, the lack of beta-galactosidase induction, in the SOS chromotest, implies a role for the RecA protein other than SOS induction. Catalase and thiourea suppress the toxic effects of oxidized ascorbate solutions, confirming that H2O2 and hydroxyl radicals are intermediate agents in the damaging action. Single-strand breaks were detected in DNA from treated cells.
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PMID:Ascorbate-copper induced DNA lesions and repair in Escherichia coli K12 cells. 300 73

Effects of plasmolysis and spheroplast formation on deoxyribonucleic acid (DNA), ribonucleic acid (RNA), protein, and phospholipid synthesis by Escherichia coli strain THU were studied. RNA and protein synthesis were severely diminished. DNA and phospholipid synthesis were inhibited, but less so; they could be partly restored. DNA synthesis could be restored by replacing thymine in the medium with thymidine, and phospholipid synthesis, by adding back small quantities of soluble cell extract. Plasmolysis effected marked reductions in rates of growth and macro-molecule synthesis, and temporarily reduced culture viability. Plasmolysis also caused an anomalous stimulation of phospholipid synthesis. Spheroplasts and plasmolyzed cells synthesized small amounts of ribosomal RNA that sedimented normally. However, this ribosomal RNA was very inefficiently packaged to ribosome subunits. Spheroplasts were unable to carry out induced synthesis of beta-galactosidase, and plasmolyzed cells were delayed in this function. Radioautographs examined in an electron microscope showed that DNA synthesis in plasmolyzed cells and spheroplasts was performed by a substantial fraction of the culture populations. That DNA and membrane were associated in the spheroplasts used in this study was suggested by formation of M-bands containing membrane and most of the cell's DNA. The results are discussed in terms of alterations of membrane structure and conformation attending plasmolysis and spheroplasting.
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PMID:Synthetic capabilities of plasmolyzed cells and spheroplasts of Escherichia coli. 491 54