Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

The sequence of the COOH-terminal third (omega) of beta-galactosidase is presented. The size of the 7 cyanogen bromide peptides of this segment is larger on the average, about 52 amino acid residues as compared to an average size of 42 for cyanogen bromide peptides in the whole molecule. Tyrosine, phenylalanine, and valine are low in this segment whereas alanine and lysine are high. This region has a slight excess of basic groups.
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PMID:Amino acid sequence of beta-galactosidase. X. Sequence of the COOH-terminal segment, CNBr peptides 18 to 24, residues 654 to 1021. 9 97

A mutant of Escherichia coli is described whose cells show a spherical or irregular morphology, associated with leakage of beta-galactosidase and other intracellular proteins. The expression of the morphologic abnormality is most marked when the mutant is grown in rich media and is suppressed by D-alamine, D-serine, D-glutamate, or glycine supplementation. D-Alanine is the most effective amino acid supplement, half maximally supressing this anomalous property at a concentration of 75 mug/ml, as measured by the reduction in beta-galactosidase released from the cells. The mutant is more sensitive to penicillin G, D-methionine, and D-valine and it is relatively resistant to lysozyme. These phenotypic abnormalities are likewise corrected by the above supplementations. The relative rates of peptidoglycan synthesis in mutant and parent, grown under restrictive conditions, were measured both in vivo and in vitro by rates of incorporation of L-[14-D]alanine and uridine-5'-diphosphate-N-acetyl-D-[1-15C-A1-glucosamine, respectively. There is not metabolic block in the biosynthesis of uridine-5'-diphosphate-N-acetyl-muramyl-pentapeptide as shown by enzymic analysis and the lack of accumulation of uridine-5'-diphosphate-N-acetylmuramyl-peptide precursors. These preliminary studies suggest that the mutant possesses a defect in the biosynthesis of peptidoglycan although the exact lesion has not yet been established.
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PMID:D-Alanine-requiring cell wall mutant of Escherichia coli. 109 98

Adenovirus DNA polymerase (AdPol) contains three clusters of basic amino acids within the N-terminal 48 amino acids: RARR, which begins at amino acid 8, RRRVR, which begins at amino acid 25, and RARRRR, which begins at amino acid 41. These clusters are designated BS I, BS II, and BS III, respectively. (The amino acid codes are: R, arginine; A, alanine; V, valine.) Mutational analysis of these noncontiguous clusters showed that AdPol contains a novel organization of bipartite nuclear localization signals (NLS) that interact differentially to serve in the nuclear targeting of AdPol or of chimeric proteins in which AdPol is linked to Escherichia coli beta-galactosidase (beta-gal). The region containing BS I and BS II functioned interdependently as an NLS for the nuclear targeting of AdPol, for which BS III was dispensible. However, the region containing BS II and BS III constituted a second and more efficient bipartite NLS for the nuclear targeting of the AdPol-E. coli beta-gal fusion protein. Moreover, deletion or limited insertion of amino acids in the spacer region between BS II and BS III did not affect their nuclear targeting function for these fusion proteins. Chou-Fasman predictive analysis of protein secondary structure in the vicinity of the bipartite NLS sequences supports a model in which protein conformation in the spacer region may play an important role in bringing these clusters of basic amino acids into close proximity, allowing them to function as nuclear targeting signals for this class of nuclear proteins.
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PMID:Three basic regions in adenovirus DNA polymerase interact differentially depending on the protein context to function as bipartite nuclear localization signals. 177 81

We have used a microinjection approach to identify a domain of the simian virus 40 (SV40) structural proteins Vp2 and Vp3(Vp2/3) responsible for their nuclear transport. By using both synthetic peptides, containing small regions of Vp2/3 conjugated to bovine serum albumin (BSA), and beta-galactosidase-Vp3 fusion proteins, we have narrowed this nuclear transport signal (NTS) to 9 amino acids (198 to 206 of Vp3 or 316 to 324 of Vp2), Gly-Pro-Asn-Lys-Lys-Lys-Arg-Lys-Leu. The porter proteins carrying the NTS or mutant NTS were microinjected into the cytoplasm of TC7 cells and their subcellular localization following the subsequent incubation period was determined immunologically using anti-BSA IgG or anti-beta-galactosidase. The 9-residue NTS peptide localized BSA into the nucleus of injected cells, changing lysine-202 to threonine or valine abolished this accumulation while changing arginine-204 to lysine did not grossly affect transport. A peptide containing the carboxyl-terminal 13 residues of Vp3 failed to localize BSA to the nucleus. Several single or double point mutations at Vp3 residues 202 and 204 have been introduced by site-directed mutagenesis. Vp3 residues 194-234, containing either a wild-type or mutated sequence at 202 and/or 204, were expressed in Escherichia coli as Vp3-beta-galactosidase fusion proteins. Addition of the carboxyl-terminal 40 residues, but not an internal 150 residues, to otherwise cytoplasmic beta-galactosidase promoted entry of the fusion protein into the nucleus. Changing lysine-202 into threonine, valine, or methionine abolished this nuclear accumulation as did changing arginine-204 into lysine. A double mutant at both positions was also blocked. We have also observed that the lectin wheat germ agglutinin inhibits the nuclear accumulation of BSA carrying the Vp2/3 NTS while the lectin concanavalin A had no effect. These data indicate that even small nuclear proteins can contain NTS's which most likely utilize a mechanism for nuclear import similar to that described for other larger proteins.
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PMID:Simian virus 40 Vp2/3 small structural proteins harbor their own nuclear transport signal. 184 70

Several fusion proteins of our previously chemically synthesized gene encoding the interleukin-2-receptor alpha subunit (IL-2R alpha or Tac protein) were constructed. They were designed in order to be cleavable by cyanogen bromide. Thus, the original internal methionines of the IL-2R alpha were replaced by either alanine, valine, leucine or isoleucine, based on secondary structure predictions. Additionally, aspartate at position 6 was substituted for glutamate in order to stabilize the acid-labile Asp-Pro bond. Direct C-terminal fusion of total beta-galactosidase and portions thereof did not result in substantial amounts of the expected construct. Ternary fusions consisting of beta-galactosidase domains N- and C-terminally fused to the mutant synthetic methionine-free interleukin-2 receptor alpha subunit (synIL-2R alpha) yielded inclusion bodies amounting to 4-7% of the total protein. This first overexpression of a type I membrane receptor can be rationalized by the known beta-galactosidase structure models. The fusion protein can be cleaved with cyanogen bromide, isolated and the resulting synIL-2R alpha detected by Western blot analysis.
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PMID:Overexpression in Escherichia coli of a methionine-free designed interleukin-2 receptor (Tac protein) based on a chemically cleavable fusion protein. 212 81

The oxyR gene is required for the induction of a regulon of hydrogen peroxide-inducible genes in Escherichia coli and Salmonella typhimurium. The E. coli oxyR gene has been cloned and sequenced, revealing an open reading frame (305 amino acids) that encodes a 34.4-kDa protein, which is produced in maxicells carrying the oxyR clone. The OxyR protein shows homology to a family of positive regulatory proteins including LysR in E. coli and NodD in Rhizobium. Like them, oxyR appears to be negatively autoregulated: an oxyR::lacZ gene fusion produced 5-fold higher levels of beta-galactosidase activity in oxyR null mutants compared to oxyR+ controls, and extracts from an OxyR-overproducing strain were able to protect regions (-27 to +21) of the oxyR promoter from DNase I digestion. DNA sequence analysis of the oxyR2 mutation, which causes overexpression of oxyR-regulated proteins in the absence of oxidative stress, showed that the oxyR2 phenotype is due to a missense mutation (C.G to T.A transition) that changes alanine to valine at amino acid position 234 of OxyR.
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PMID:OxyR, a positive regulator of hydrogen peroxide-inducible genes in Escherichia coli and Salmonella typhimurium, is homologous to a family of bacterial regulatory proteins. 247 Nov 87

Escherichia coli and Salmonella typhimurium preferentially utilize sugar substrates of the phosphoenol-pyruvate:glycose phosphotransferase system (PTS) when the growth medium also contains other sugars. This phenomenon, diauxic growth, is regulated by the crr gene, which encodes the PTS protein IIIGlc (Saffen, D.W., Presper, K.A., Doering, T.L., and Roseman, S. (1987) J. Biol. Chem. 16241-16253). We have proposed that non-PTS permeases are regulated by their interaction with IIIGlc, and in vitro studies from other laboratories have provided support for this model, but the in vivo effects of excess IIIGlc are not known. In the present studies, transformed cells that overproduced IIIGlc 2- and 10-fold, respectively, were constructed from a pts+ strain of E. coli and plasmids containing the crr gene. In the 2-fold overproducer, fermentation of, and growth on the non-PTS carbohydrates glycerol, lactose, maltose, and melibiose was generally more sensitive to the glucose analogue methyl-alpha-D-glucopyranoside than in a control strain containing normal levels of IIIGlc. In addition, inhibition of lactose permease activity by methyl-alpha-glucoside (inducer exclusion) was more effective in the 2-fold overproducer than in the control strain, particularly when the permease activity was high. The 10-fold IIIGlc overproducing strain had a requirement for the amino acids methionine, isoleucine, leucine, and valine that may or may not be related to the increased concentration of IIIGlc. Fermentation of non-PTS carbohydrates was also poor in the latter strain. Finally, lactose permease activity was 50% of that in control cells containing the same levels of beta-galactosidase, and the lactose permease activity in the IIIGlc overproducer was reduced to an extremely low level in the presence of methyl alpha-glucoside. Thus there is an inverse relationship between the cellular concentration of IIIGlc and the ability to metabolize non-PTS substrates. The results are consistent with the model where inducer exclusion is affected by a direct interaction between IIIGlc and a non-PTS transport system.
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PMID:Sugar transport by the bacterial phosphotransferase system. In vivo regulation of lactose transport in Escherichia coli by IIIGlc, a protein of the phosphoenolpyruvate:glycose phosphotransferase system. 282 84

The enzymatic activities of 53 strains of Pseudomonas cepacia were determined by using the API ZYM system. Strong alkaline phosphatase, acid phosphatase, butyrate esterase, caprylate esterase, myristate lipase, leucine arylamidase, and phosphoamidase activities were consistently detected in all strains. Weak activities were observed for valine arylamidase, beta-glucosidase, and N-acetyl-beta-glucosaminidase. No activities could be demonstrated for cystine arylamidase, trypsin, chymotrypsin, alpha-galactosidase, beta-galactosidase, beta-glucuronidase, alpha-glucosidase, alpha-mannosidase, and alpha-fucosidase. Enzymatic activities of pseudomonads may provide useful information about their pathogenesis and information for identification of Pseudomonas species.
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PMID:Enzymatic characterization of Pseudomonas cepacia by API ZYM profile. 335 98

Nineteen hydrolytic enzymes were detected in individual adult Pergamasus longicornis (Berlese) mites--amylase, hide protease, alkali phosphatase, esterase (C4), esterase lipase (C8), lipase (C14), leucine arylamidase, valine arylamidase, cystine arylamidase, acid phosphatase, phosphoamidase, alpha-galactosidase, beta-galactosidase, beta-glucuronidase, alpha-glucosidase, beta-glucosidase, N-acetyl-beta-glucosaminidase, alpha-mannosidase, and alpha-fucosidase. All but the phosphatases were detected for the first time. Tryptic and chymotryptic activity were consistently not demonstrable. Comparisons are made with saprophagous mites. No clear enzymic specialization for predation was found.
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PMID:Digestion in the soil predatory mite Pergamasus longicornis (Berlese) (Acari: Mesostigmata: Parasitidae)--detectable hydrolases. 356 25

The concentration of rifampin necessary to affect the initiation of ribonucleic acid (RNA) synthesis quickly in Escherichia coli strains K-12 and 15TAU was about 200 mug/ml, as determined by extrapolation of the effect of the drug on the induction of beta-galactosidase synthesis. A lag in the action of rifampin of about 10 s was confirmed. Rifampin was then used as a probe to compare RNA synthesis in growing and amino acid-starved E. coli. Restoring arginine to arginine-starved strain 15TAU immediately after rifampin inhibition did not detectably restore the rate of uracil uptake to that of uninhibited cells. The residual rate of RNA synthesis (corrected for acid-soluble triphosphate specific activities) after rifampin treatment of both growing and isoleucine-starved (valine-inhibited) cultures of strain K-12 showed similar decay kinetics. These findings support the notion that amino acid starvation blocks the initiation of some RNA transcription units, but do not rule out other possibilities.
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PMID:Decay of ribonucleic acid synthesis in amino acid-starved Escherichia coli after rifampin treatment. 459 64


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