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)

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

Epstein-Barr Virus (EBV) replication and transcription activator (Rta/BRLF1) is an immediate-early transcription factor that controls the conversion of the latent viral genome into one undergoing lytic replication. By using a doxycycline-inducible expression system, the present study demonstrates that EBV Rta efficiently elicits growth arrest in the human epithelial cell line HEK293. In cells arrested by EBV Rta, the expression of p21 (CDKN1A), p27 (CDKN1B) and cyclin E were increased. In contrast, the levels of cyclin D1, CDK4 and CDK6 were sharply decreased. Activation of the host cell DNA damage response (DDR), indicated by the increasing phosphorylation of H2AX and p53 Ser15, was observed on day 3 and day 5 after EBV Rta expression, respectively. Finally, EBV Rta arrested cells exhibited strong senescence-associated beta-galactosidase staining on day 10 after doxycycline induction. Together, these results indicate that, in addition to triggering viral lytic replication in epithelial cells, EBV Rta concurrently initiates a cellular senescence program that was previously undocumented. This finding, showing Rta may be centrally involved in inducing a host cell state amenable to efficient viral reproduction, in addition to its previously characterized regulation of viral transcription, provides new perspectives in understanding EBV pathogenesis.
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PMID:The Epstein-Barr virus replication and transcription activator, Rta/BRLF1, induces cellular senescence in epithelial cells. 1909 30


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