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

---

Query: EC:3.2.1.23 (beta-galactosidase)
14,648 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Herpesviruses employ many mechanisms to evade the immune response, allowing them to persist life-long in their hosts. The Epstein-Barr virus (EBV) nuclear antigen 1 (EBNA-1) and, more recently, the latency-associated nuclear antigen 1 (LANA-1) of the Kaposi Sarcoma Herpesvirus have been shown to function as in cis-acting inhibitors of antigen presentation. In both proteins, long simple repeat elements are responsible for the inhibition, but the sequences of these repeats are strongly dissimilar. Intriguingly, EBNA-1 mRNA contains a large nested open reading frame that codes for a 40.7kDa strongly acidic protein, in addition to the full-length EBNA-1. This protein, here called pGZr, has a 230 amino-acids long glycine, glutamine, and glutamic acid-rich repeat ('GZ' repeat), highly similar (65% amino-acid identity) to the acidic repeat of LANA-1. To evaluate if pGZr, like EBNA-1 and LANA-1, can inhibit antigen presentation in cis, we fused the nested ORF with the E. coli-derived LacZ gene encoding beta-galactosidase. Whereas cells producing the unmodified beta-galactosidase readily present the H-2L(d)-restricted CTL epitope TPHPARIGL, which resides in the C-terminal region of beta-galactosidase, cells producing the pGZr-beta-galactosidase fusion protein do not. Also shorter fragments of the repeat can inhibit peptide presentation. Even though the physiological function of pGZr remains to be elucidated, the GZ-repeat protein may be valuable as inhibitor of presentation of antigenic peptides derived from transgenes in gene therapy.
...
PMID:The nested open reading frame in the Epstein-Barr virus nuclear antigen-1 mRNA encodes a protein capable of inhibiting antigen presentation in cis. 1744 1

The mechanisms that promote and regulate transcription in mycoplasmas are poorly understood. Here, a promoter-probe vector based on the pMTnTetM438 minitransposon and containing a promoterless lacZ reporter gene was constructed to analyse Mycoplasma genitalium transcription in vivo. Recovered transposon insertions were in monocopy, with 16 % expressing enough beta-galactosidase (beta-Gal) to yield colonies exhibiting a detectable blue colour. A sample of 52 blue colonies was propagated and selected for further analyses. The beta-Gal activity of the corresponding cultures was measured to quantify, in a reproducible way, the transcription levels of the interrupted ORFs. Several insertions were found in sense with the interrupted ORF, but surprisingly there was also a number of insertions in non-coding regions, many of them in repetitive DNA regions known as MgPa islands. Moreover, 30 % of the analysed transposon insertions had the lacZ gene in the opposite orientation to the coding frame, suggesting the existence of antisense transcripts that may be involved in the control of gene expression in M. genitalium.
...
PMID:A new promoterless reporter vector reveals antisense transcription in Mycoplasma genitalium. 1766 Apr 38

Dihydroxyacetone synthase (DHAS) is a key enzyme involved in the assimilation of methanol in Mycobacterium sp. strain JC1 DSM 3803. The structural gene encoding DHAS in Mycobacterium sp. strain JC1 was cloned using random-primed probes synthesized after PCR with synthetic primers based on the amino acid sequences conserved in two yeast DHASs and several transketolases. The cloned gene, dasS, had an ORF of 2193 nt, encoding a protein with a calculated molecular mass of 78,197 Da. The deduced amino acid sequence of dasS contained an internal sequence of Mycobacterium sp. strain JC1 DHAS and exhibited 29.2 and 27.3 % identity with those of Candida boidinii and Hansenula polymorpha enzymes, respectively. Escherichia coli transformed with the cloned gene produced a novel protein with a molecular mass of approximately 78 kDa, which cross-reacted with anti-DHAS antiserum and exhibited DHAS activity. Primer-extension analysis revealed that the transcriptional start site of the gene was the nucleotide A located 31 bp upstream from the dasS start codon. RT-PCR showed that dasS was transcribed as a monocistronic message. Northern hybridization and beta-galactosidase assay with the putative promoter region of dasS revealed that the gene was transcribed only in cells growing on methanol. The expression of dasS in Mycobacterium sp. strain JC1 was free from catabolite repression.
...
PMID:Cloning, characterization and expression of a gene encoding dihydroxyacetone synthase in Mycobacterium sp. strain JC1 DSM 3803. 1804 31

Most Aggregatibacter actinomycetemcomitans strains express relatively low levels of leukotoxin, encoded by the orfA-ltxCABD operon. However, several strains isolated from patients with localized aggressive periodontitis are hyperleukotoxic and transcribe the ltx operon at high levels. These strains possess a copy of IS1301 in the ltx promoter and previous studies have suggested that the presence of the insertion sequence increases ltx transcription by uncoupling a cis-acting negative regulator of ltx expression from the basal elements of the ltx promoter. However, we now report that replacing IS1301 with an equal length of random sequence has little effect on transcriptional activity of the ltx promoter, suggesting that the physical displacement of the negative regulatory element does not contribute to the hyperleukotoxic phenotype of IS1301-containing strains. Instead, we show that a -10-like element upstream of the transposase ORF of IS1301 is required for increased transcriptional activity of the ltx promoter. Site-specific mutation of the -10 sequence, or reversing the orientation of IS1301 relative to the basal ltx promoter elements, reduced transcriptional activity to levels exhibited by the native ltx promoter. However, no increase in transcription was observed when IS1301 was recombinantly inserted into a ltx promoter that contained a truncated copy of orfA, suggesting that an intact orfA may also be required for IS1301-mediated induction of ltxCABD. Therefore, to determine if orfA functions as a regulator of ltx expression, three independent ltx-promoter-lacZ-reporter constructs containing frameshift mutations in orfA were analysed. Each exhibited significantly lower expression of beta-galactosidase than the control reporter with intact orfA. In addition, OrfA protein was shown, by mobility shift electrophoresis, to interact with the ltx promoter at or downstream of the -35 sequence. These results suggest that a potential transposase promoter and the OrfA polypeptide may modulate leukotoxin expression in hyperleukotoxic A. actinomycetemcomitans strains containing IS1301.
...
PMID:Induction of Aggregatibacter actinomycetemcomitans leukotoxin expression by IS1301 and orfA. 1822 57

A novel beta-galactosidase of 120 kDa (BgaBM) from Bacillus megaterium 2-37-4-1 was purified, and its gene (bgaBM) was analyzed and expressed. It displayed wide acceptor specificity for transglycosylation with a series of acceptors, including pentose, hexose, hydroxyl, and alkyl alcohol using o-nitrophenyl-beta-D-galactoside (ONPG) as a donor. BgaBM preferentially hydrolyzed ONPG in all tested substrates and showed maximum activity at pH 7.5-8.0 and 55 degrees C. It was stable at pH 6.0-9.0 below 40 degrees C. The K(m) and V(max) values for ONPG and lactose were 9.5 mM, 16.6 mM/min and 12.6 mM, 54.4 mM/min, respectively. The nucleotide sequence of the bgaBM gene consists of an ORF of 3,105 bp corresponding to 118 kDa protein, which indicates that BgaBM is a modular enzyme in the glycosyl hydrolase family 2, including conserved sugar-binding domain, acid-base catalyst, and immunoglobulin-like beta-sandwich domain. The possible acid/base and nucleophile sites of BgaBM were estimated to be E481 and E547, respectively. Furthermore, expression of the bgaBM gene in Escherichia coli and purification of the recombinant enzyme were performed. The recombinant enzyme showed similar biochemical characteristics to natural enzyme.
...
PMID:Purification and characterization of a novel beta-galactosidase with transglycosylation activity from Bacillus megaterium 2-37-4-1. 1868 99

The veA gene is one of the key genes in regulating sexual development of Aspergillus nidulans. During the study on the veA gene, it was observed that the veA expression level is slightly higher in a veA1 mutant than in a wild type at 37 degrees C, suggesting that the wild type veA gene is necessary for the negative regulation of the veA expression. In the veA1 mutant, the veA expression was higher than in a wild type grown at 42 degrees C but equal at 30 degrees C. Furthermore, in a veA deletion mutant having its own promoter and the N-terminus of the VeA ORF, expression of the N-terminus by the veA promoter was highly up-regulated, supporting the possibility that the veA gene is important for the negative regulation of the veA expression. Analyses of the lacZ transcript and the beta-galactosidase activity from the reporter strains in the veA1 background, which were constructed by transformation of the lacZ reporter plasmids containing the lacZ gene under the control of the intact or the truncated veA promoters from the -943 to +262 bp region, showed that the truncated promoters produced more veA transcript and higher beta-galactosidase activity than the intact one at 30 degrees C, but equal at 42 degrees C. In addition, the serial-deletion analysis of the veA promoter identified a crucial region in the promoter from -943 to -740 bp for this derepression of the veA expression. Taken together, these results indicated that the veA gene is necessary for the negative regulation of the veA expression. Moreover, the veA expression was derepressed in the light-illuminated condition, where the VeA protein is hardly transported into the nucleus.
...
PMID:The veA gene is necessary for the negative regulation of the veA expression in Aspergillus nidulans. 1947 57

Carbonic anhydrase (CA; [EC 4.2.1.1]) is a ubiquitous enzyme catalysing the reversible hydration of CO(2) to bicarbonate, a reaction that supports various biochemical and physiological functions. Genome analysis of Azospirillum brasilense, a nonphotosynthetic, nitrogen-fixing, rhizobacterium, revealed an ORF with homology to beta-class carbonic anhydrases (CAs). Biochemical characteristics of the beta-class CA of A. brasilense, analysed after cloning the gene (designated as bca), overexpressing in Escherichia coli and purifying the protein by affinity purification, revealed that the native recombinant enzyme is a homotetramer, inhibited by the known CA inhibitors. CA activity in A. brasilense cell extracts, reverse transcriptase (RT)-PCR and Western blot analyses showed that bca was constitutively expressed under aerobic conditions. Lower beta-galactosidase activity in A. brasilense cells harbouring bca promoter: lacZ fusion during the stationary phase or during growth on 3% CO(2) enriched air or at acidic pH indicated that the transcription of bca was downregulated by the stationary phase, elevated CO(2) levels and acidic pH conditions. These observations were also supported by RT-PCR analysis. Thus, beta-CA in A. brasilense seems to be required for scavenging CO(2) from the ambient air and the requirement of CO(2) hydration seems to be higher for the cultures growing exponentially at neutral to alkaline pH.
...
PMID:Regulation of expression and biochemical characterization of a beta-class carbonic anhydrase from the plant growth-promoting rhizobacterium, Azospirillum brasilense Sp7. 1969 14

A psychrotrophic bacterium producing a cold-adapted beta-galactosidase upon growth at low temperatures was classified as Arthrobacter sp. 20B. A genomic DNA library of strain 20B introduced into Escherichia coli TOP10F' and screening on X-Gal (5-bromo-4-chloro-3-indolyl-beta-D-galactopyranoside)-containing agar plates led to the isolation of beta-galactosidase gene. The beta-galactosidase gene (bgaS) encoding a protein of 1,053 amino acids, with a calculated molecular mass of 113,695 kDa. Analysis of the amino acid sequence of BgaS protein, deduced from the bgaS ORF, suggested that it is a member of the glycosyl hydrolase family 2. A native cold-adapted beta-galactosidase was purified to homogeneity and characterized. It is a homotetrameric enzyme, each subunit being approximately 116 kDa polypeptide as deduced from native and SDS-PAGE, respectively. The beta-galactosidase was optimally active at pH 6.0-8.0 and 25 degrees Celsius. P-nitrophenyl-beta-D-galactopyranoside (PNPG) is its preferred substrate (three times higher activity than for ONPG-o-nitrophenyl-beta-D-galactopyranoside). The Arthrobacter sp. 20B beta-galactosidase is activated by thiol compounds (53% rise in activity in the presence of 10 mM 2-mercaptoethanol), some metal ions (activity increased by 50% for Na(+), K(+) and by 11% for Mn(2+)) and inactivated by pCMB (4-chloro-mercuribenzoic acid) and heavy metal ions (Pb(2+), Zn(2+), Cu(2+)).
...
PMID:A new beta-galactosidase with a low temperature optimum isolated from the Antarctic Arthrobacter sp. 20B: gene cloning, purification and characterization. 1977 12

Recently, the gene coding for a new beta-glucuronidase enzyme has been identified and cloned from Streptococcus equi subsp. zooepidemicus. This is another report of a beta-glucuronidase gene cloned from bacterial species. The ORF Finder analysis of a sequenced DNA (EMBL, AJ890474) revealed a presence of 1,785 bp large ORF potentially coding for a 594 aa protein. Three protein families in (Pfam) domains were identified using the Conserved Domain Database (CDD) analysis: Pfam 02836, glycosyl hydrolases family 2, triose phosphate isomerase (TIM) barrel domain; Pfam 02837, glycosyl hydrolases family 2, sugar binding domain; and Pfam 00703, glycosyl hydrolases family 2, immunoglobulin-like beta-sandwich domain. To gain more insight into the enzymatic activity, the domains were used to generate a bootstrapped unrooted distance tree using ClustalX. The calculated distances for two domains, TIM barrel domain, and sugar-binding domain were comparable and exhibited similarity pattern based on function and thus being in accordance with recently published works confirming beta-glucuronidase activity of the enzyme. The calculated distances and the tree arrangement in the case of centrally positioned immonoglobulin-like beta-sandwich domain were somewhat higher when compared to other two domains but clustering with other beta-glucuronidases was rather clear. Nine proteins, including beta-glucuronidases, beta-galactosidase, and mannosidase were selected for multiple alignment and subsequent distance tree creation.
...
PMID:Bioinformatics characterization of potential new beta-glucuronidase from Streptococcus equi subsp. zooepidemicus. 2007 37

The analysis of the cold-shock domain (CSD)-encoding genes, capB and cspA, by PCR amplification showed presence of capB in all 18 Antarctic Pseudomonas isolates, but the absence of cspA. Nucleotide sequence analysis of capB ORF from a biodegradative Pseudomonas 30/3 and its regulatory sequences including the promoter and 5'-UTR was determined and compared with the other CSD-encoding genes. Expression analysis using translational gene fusion of the putative capB promoter and its flanking sequence from Pseudomonas sp. 30/3 with lacZ' exhibited a significant increase in beta-galactosidase activity at 15 and 6 degrees C. Unlike the expression of E. coli CspA, Pseudomonas sp. 30/3 showed a slow but steady increase of the CapB expression at 6 degrees C. Subcellular localization of CapB at 6 degrees C showed accumulation in and around the nucleoid whereas at 22 or 30 degrees C, it was identified around the nucleoid as well as in the cytosol. Our study attempts to elucidate the detailed structure of capB from Pseudomonas 30/3 and the role of 5'UTR in the transcriptional regulation along with the possible role of CapB in transcription and translation suited for the cold adaptation of this bacterium in Antarctic environment.
...
PMID:Occurrence and distribution of capB in Antarctic microorganisms and study of its structure and regulation in the Antarctic biodegradative Pseudomonas sp. 30/3. 2009 Oct 73


<< Previous 1 2 3 4 5 Next >>

---