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Identification of the  4514 Regulatory Region, a Developmental Promoter of Myxococcus xanthus That Is Transcribed In Vitro by the Major Vegetative RNA Polymerase.Tong Hao, 2002. 4514 is the site of a Tn5 lac insertion in the Myxococcus xanthus genome that fuses lacZ expression to a developmentally regulated promoter . DNA upstream of the insertion site was cloned, and the promoter was localized . The promoter resembles vegetative promoters in sequence, and
 A RNA polymerase, the major form of RNA polymerase in growing M . xanthus, initiated transcription from this promoter in vitro . Two complete open reading frames were identified downstream of the promoter and before the
4514 insertion . The first gene product (ORF1) has a putative helix-turn-helix DNA-binding motif and shows sequence similarity to transcriptional regulators . ORF2 is most similar to subunit A of glutaconate coenzyme A (CoA) transferase, which is involved in glutamate fermentation . Tn5 lac
4514 is inserted in the third codon of ORF3, which is similar to subunit B of glutaconate CoA-transferase . An orf1 disruption mutant exhibited a mild sporulation defect, whereas neither a disruption of orf2 nor insertion
4514 in orf3 caused a defect . Based on DNA sequence analysis, the three genes are likely to be cotranscribed with a fourth gene whose product is similar to alcohol dehydrogenases . ORF1 delays and reduces expression of the operon during development, but relief from this negative autoregulation does not fully explain the regulation of the operon, because expression from a small promoter-containing fragment is strongly induced during development of an orf1 mutant . Also, multiple upstream DNA elements are necessary for full developmental expression . These results suggest that transcriptional activation also regulates the operon .
4514 is the first example of a developmentally regulated M . xanthus operon that is transcribed by the major vegetative RNA polymerase, and its regulation appears to involve both negative autoregulation by ORF1 and positive regulation by one or more transcriptional activators .
Forespore-Specific Expression of Bacillus subtilis yqfS, Which Encodes Type IV Apurinic/Apyrimidinic Endonuclease, a Component of the Base Excision Repair Pathway. Norma Urtiz-Estrada, 2003.The temporal and spatial expression of the yqfS gene of Bacillus subtilis, which encodes a type IV apurinic/apyrimidinic endonuclease, was studied . A reporter gene fusion to the yqfS opening reading frame revealed that this gene is not transcribed during vegetative growth but is transcribed during the last steps of the sporulation process and is localized to the developing forespore compartment . In agreement with these results, yqfS mRNAs were mainly detected by both Northern blotting and reverse transcription-PCR, during the last steps of sporulation . The expression pattern of the yqfS-lacZ fusion suggested that yqfS may be an additional member of the E  G regulon . A primer extension product mapped the transcriptional start site of yqfS, 54 to 55 bp upstream of translation start codon of yqfS . Such an extension product was obtained from RNA samples of sporulating cells but not from those of vegetatively growing cells . Inspection of the nucleotide sequence lying upstream of the in vivo-mapped transcriptional yqfS start site revealed the presence of a sequence with good homology to promoters preceding genes of the
G regulon . Although yqfS expression was temporally regulated, neither oxidative damage (after either treatment with paraquat or hydrogen peroxide) nor mitomycin C treatment induced the transcription of this gene .
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