Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.30.1 (S1 nuclease)
 3,660 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Within the chromosome of the archaebacterium Sulfolobus sp. B12, a 7.4 kb region was identified which displayed extensive sequence similarities to the 15.5 kb genetic element SSV1 carried by the same strain both as a circular form and as a site-specifically integrated copy. DNA sequence analysis indicated that this 7.4 kb region (designated SSV1intB) represented an SSV1-like element distinguishable from the full-length integrated copy (designated SSV1intA) by extensive deletions and point mutations. The physical organization of DNA sequences of SSV1intB indicated that this element was integrated at the same attP site as previously identified for SSV1intA. A comparison of the DNA sequences at the left attachment sites of SSV1intA and SSV1intB revealed that they both represented very similar putative arginine tRNA genes followed by a 10 bp inverted repeat sequence. S1 nuclease mapping experiments indicated that these tRNA genes are transcribed.
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PMID:Identification and characterization of a defective SSV1 genome integrated into a tRNA gene in the archaebacterium Sulfolobus sp. B12. 169 36

The level of the vitamin B12 transport protein BtuB in the outer membrane of Escherichia coli is strongly reduced by growth in the presence of cobalamins. Previous analyses of regulatory mutants and of btuB-lacZ fusions indicated that the primary site of btuB gene regulation was at the translational level, and this required sequences throughout the 240-nucleotide (nt) leader region. Cobalamin-dependent regulation of transcriptional fusions was of a lesser magnitude but required, in addition to the leader, sequences within the first 100 nt of the coding sequence, termed the translated regulatory region (TRR). To analyze the process of transcription-level regulation of btuB in E. coli, the levels and metabolism of btuB RNA were analyzed by S1 nuclease protection assays, and mutations that alter the coupling of translational and transcriptional control were analyzed. Expression of transcriptional fusions was found to correlate with changes in the level of intact btuB RNA and was related to changes in the metabolic stability of the normally long-lived RNA. Mutational analysis showed that the btuB start codon and a hairpin structure that can sequester the Shine-Dalgarno sequence are necessary for cobalamin-dependent regulation and that translation of the TRR is necessary for extended RNA stability and for expression of the transcriptional fusion. The absence of regulation at the stage of transcription initiation was confirmed by the findings that several truncated btuB RNA fragments were expressed in a constitutive manner and that the normal regulatory response occurred even when the btuB promoter and upstream sequences were replaced by the heterologous bla and lac promoters. Transcription driven by phage T7 RNA polymerase was not regulated by cobalamins, although some regulation at the translational level was retained. Cobalamin-dependent changes in RNA structure were suggested from the RNase III-dependent production of a transcript fragment that is made only in the presence of cobalamin and is independent of the regulatory outcome. These results indicate that the primary control of btuB expression by cobalamin occurs at the level of translation initiation, which directly affects the level and stability of btuB RNA in a process that requires the presence of the intact translated regulatory region.
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PMID:Coupled changes in translation and transcription during cobalamin-dependent regulation of btuB expression in Escherichia coli. 985 20

LdrP (TT_P0055) (LitR-dependent regulatory protein) is one of the four cAMP receptor protein (CRP)/FNR family transcriptional regulators retained by the extremely thermophilic bacterium Thermus thermophilus. Previously, we reported that LdrP served as a positive regulator for the light-induced transcription of crtB, a carotenoid biosynthesis gene encoded on the megaplasmid of this organism. Here, we showed that LdrP also functions as an activator of the expression of genes clustered around the crtB gene under the control of LitR, an adenosyl B12-bound light-sensitive regulator. Transcriptome analysis revealed the existence of 19 LitR-dependent genes on the megaplasmid. S1 nuclease protection assay confirmed that the promoters preceding TT_P0044 (P44), TT_P0049 (P49) and TT_P0070 (P70) were activated upon illumination in the WT strain. An ldrP mutant lost the ability to activate P44, P49 and P70, whilst disruption of litR resulted in constitutive transcription from these promoters irrespective of illumination, indicating that these genes were photo-dependently regulated by LdrP and LitR. An in vitro transcription experiment demonstrated that LdrP directly activated mRNA synthesis from P44 and P70 by the Thermus RNA polymerase holocomplex. The present evidence indicated that LdrP was the positive regulator essential for the transcription of the T. thermophilus light-inducible cluster encoded on the megaplasmid.
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PMID:LdrP, a cAMP receptor protein/FNR family transcriptional regulator, serves as a positive regulator for the light-inducible gene cluster in the megaplasmid of Thermus thermophilus. 2529 6