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

The transcription of the 14 p-gvp genes involved in gas vesicle formation of Halobacterium salinarum PHH1 is driven by the four promoters pA, pD, pF and pO. The regulation of these promoters was investigated in Haloferax volcanii transformants with respect to the endogenous regulatory proteins GvpE and GvpD. Northern analyses demonstrated that the transcription derived from the pA and pD promoters was enhanced by GvpE, whereas the activities of the pF and pO promoters were not affected. Similar results were obtained using promoter fusions with the bgaH reporter gene encoding an enzyme with beta-galactosidase activity. The largest amount of specific beta-galactosidase activity was determined for pA-bgaH transformants, followed by pF-bgaH and pD-bgaH transformants. The presence of GvpE resulted in a severalfold induction of the pA and pD promoter, whereas the pF promoter was not affected. A lower GvpE-induced pA promoter activity was seen in the presence of GvpD in the pA-bgaH/DE(ex) transformants, suggesting a function of GvpD in repression. To determine the DNA sequences involved in the GvpE-mediated activation, a 50-nucleotide region of the pA promoter was investigated by 4-nucleotide scanning mutagenesis. Some of these mutations affected the basal transcription, especially mutations in the region of the TATA box and the putative BRE sequence element, and also around position -10. Mutant E, harbouring a sequence with greater identity to the consensus BRE element, showed a significantly enhanced basal promoter activity compared to wild-type. Mutations not affecting basal transcription, but yielding a reduced GvpE-mediated activation, were located immediately upstream of BRE. These results suggested that the transcription activation by GvpE is in close contact with the core transcription machinery.
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PMID:GvpE- and GvpD-mediated transcription regulation of the p-gvp genes encoding gas vesicles in Halobacterium salinarum. 1518 69

Signaling by bone morphogenetic proteins is essential for a wide variety of developmental processes. Receptor-regulated Smad proteins, Smads 1 and 5, are intracellular mediators of bone morphogenetic protein signaling. Together with Smad4, these proteins translocate to the nucleus and modulate transcription by binding to specific sequences on the promoters of target genes. We sought to map transcriptional Smad1/5 activity in development by generating embryonic stem cell lines carrying a Smad1/5-specific response element derived from the Id1 promoter coupled to beta-galactosidase or luciferase as reporters. Three independent lines (BRE-lac1, BRE-lac2 and BRE-luc) have shown the existence of an autocrine bone morphogenetic protein signaling pathway in mouse embryonic stem cells. Reporter activity was detected in chimeric embryos, suggesting sensitivity to physiological concentrations of bone morphogenetic protein. Reporter activity in embryos from transgenic mouse lines was detected in tissues where an essential role for active bone morphogenetic protein signaling via Smads 1 or 5 had been previously established. We have thus generated, for the first time, an in vivo readout for studying the role of Smad1/5-mediated transcriptional activity in development.
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PMID:Spatio-temporal activation of Smad1 and Smad5 in vivo: monitoring transcriptional activity of Smad proteins. 1533 32

The two gvpA promoters P(cA) and P(pA) of Halobacterium salinarum, and the P(mcA) promoter of Haloferax mediterranei were investigated with respect to growth-phase-dependent expression and regulation in Haloferax volcanii transformants using the bgaH reading frame encoding BgaH, an enzyme with beta-galactosidase activity, as reporter. For comparison, the P(fdx) promoter of the ferredoxin gene of Hbt. salinarum and the P(bgaH) promoter of Haloferax lucentense (formerly Haloferax alicantei) were analysed. P(fdx), driving the expression of a house-keeping gene, was highly active during the exponential growth phase, whereas P(bgaH) and the three gvpA promoters yielded the largest activities during the stationary growth phase. Compared to P(fdx), the basal promoter activities of P(pA) and P(mcA) were rather low, and larger activities were only detected in the presence of the endogenous transcriptional activator protein GvpE. The P(cA) promoter does not yield a detectable basal promoter activity and is only active in the presence of the homologous cGvpE. To investigate whether the P(cA)-TATA box and the BRE element were the reason for the lack of the basal P(cA) activity, these elements and also sequences further upstream were substituted with the respective sequences of the stronger P(pA) promoter and investigated in Hfx. volcanii transformants. All these promoter chimera did not yield a detectable basal promoter activity. However, whenever the P(pA)-BRE element was substituted for the P(cA)-BRE, an enhanced cGvpE-mediated activation was observed. The promoter chimeras harbouring P(pA)-BRE plus 5 (or more) bp further upstream also gained activation by the heterologous pGvpE and mcGvpE proteins. The sequence required for the GvpE-mediated activation was determined by a 4 bp scanning mutagenesis with the 45 bp region upstream of P(mcA)-BRE. None of these alterations influenced the basal promoter activity, but the sequence TGAAACGG-n4-TGAACCAA was important for the GvpE-mediated activation of P(mcA).
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PMID:In vivo analyses of constitutive and regulated promoters in halophilic archaea. 1563 22

Transcription of the genomic region involved in gas vesicle formation in Halobacterium salinarum (p-vac) and Haloferax mediterranei (mc-vac) is driven by two divergent promoters, P(A) and P(D), separated by only 35 nt. Both promoters are activated by the transcription activator GvpE which in the case of P(mcA) requires a 20-nt sequence (UAS) consisting of two conserved 8-nt sequence portions located upstream of BRE. Here, we determined the two UAS elements in the promoter region of p-vac by scanning mutageneses using constructs containing P(pD) (without P(pA)) fused to the bgaH reporter gene encoding an enzyme with beta-galactosidase activity, or the dual reporter construct pApD with P(pD) fused to bgaH and P(pA) to an altered version of gvpA. The two UAS elements found exhibited a similar extension and distance to BRE as previously determined for the UAS in P(mcA). Their distal 8-nt portions almost completely overlapped in the centre of P(pD)-P(pA), and mutations in this region negatively affected the GvpE-mediated activation of both promoters. Any alteration of the distance between BRE and UAS resulted in the loss of the GvpE activation, as did a complete substitution of the proximal 8-nt portion, underlining that a close location of UAS and BRE was very important.
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PMID:Overlapping activator sequences determined for two oppositely oriented promoters in halophilic Archaea. 1805 77