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

We have cloned a large portion of the P25 gene of Bombyx mori encoding the 25,000 dalton polypeptide which associates with fibroin to constitute the major silk protein. Its structure has been investigated by restriction mapping R-loop analysis, S1 nuclease protection experiments and nucleotide sequencing of the region spanning the 5' end of the gene and its flanking DNA. This has permitted a comparative sequence analysis of the DNA from the P25 and fibroin genes. The genes demonstrate no relatedness in their coding regions but they exhibit large blocks of sequence homology in their 5' flanking regions. In particular, the DNA upstream of the P25 gene possesses a sequence very similar to a region of fibroin 5' flanking DNA that is known to possess transcription modulation signals. The functional significance of these homologous regions is discussed with regard to the highly coordinated expression of these two genes.
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PMID:Structural organization of the P25 gene of Bombyx mori and comparative analysis of its 5' flanking DNA with that of the fibroin gene. 298 37

The study reported here describes nuclease S1 mapping of the in-vivo transcription start sites of transcription units I and III of the hook gene cluster of Caulobacter crescentus. We show that transcription units I and II of this flagellar (fla) gene cluster, which have divergent promoters with transcription start sites separated by 218 nucleotides, are under positive transcriptional control by genes in transcription unit III. The promoters of transcription units I, II, and III were compared with flagellin gene promoters P25, P27 and P29 recently identified in C. crescentus. Promoters PII, P25, and P27, which are under positive regulation by transcription units III to V have strongly conserved sequence elements at -13 and -24 with the consensus sequence (C/T)TGGC(C/G)C-N5-TTGC. The -13, -24 sequence elements are not well conserved in promoter PI, but the promoter does contain a copy of the -13 and -24 consensus sequence 23 base-pairs upstream (PI). The C. crescentus fla gene promoters are not homologous to the canonical Escherichia coli -10, -35 promoter sequence, but they are very similar to the -12, -24 nif gene promoter sequence reported for Klebsiella pneumoniae and Rhizobium sp. The four positively regulated fla gene promoters examined here also share a third conserved element designated II-1, with the consensus sequence C-C-CGGC--AAA--GC-G, located at approximately -100. We speculate that the conserved sequence elements mapping at -13, -24 and -100 are cis-acting regulatory elements required for the transcription and periodic regulation of these fla genes in the C. crescentus cell cycle.
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PMID:A set of positively regulated flagellar gene promoters in Caulobacter crescentus with sequence homology to the nif gene promoters of Klebsiella pneumoniae. 330 46