Expression of the Escherichia coli dnaX gene.
The Escherichia coli dnaX gene encodes both the tau and gamma subunits of DNA polymerase III. This gene is located immediately downstream of the adenine salvage gene apt and upstream of orf12-recR, htpG, and adk. The last three are involved in recombination, heat shock, and nucleotide biosynthesis, respectively. apt, dnaX, and orf12-recR all have separate promoters, and the first two are expressed predominantly from those separate promoters. However, use of an RNase E temperature-sensitive mutant allowed the detection of lesser amounts of polycistronic messengers extending from both the apt and dnaX promoters through htpG. Interestingly, transcription of the weak dnaX promoter is stimulated 4- to 10-fold by a sequence contained entirely within the dnaX reading frame. This region has been localized; at least a portion of the sequence (and perhaps the entire sequence) is located within a 31-bp region downstream of the dnaX promoter.
Chen
K S
KS
Department of Microbiology, University of Texas, Austin 78712-1095.
Saxena
P
P
Walker
J R
JR
D001483:Base Sequence; D004258:DNA Polymerase III / Q000235:genetics*; D017931:DNA Primers; D004926:Escherichia coli / Q000235:genetics*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D012329:RNA, Bacterial / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D015183:Restriction Mapping; D017384:Sequence Deletion; D014158:Transcription, Genetic
D017931:DNA Primers; D012329:RNA, Bacterial; D004258:DNA Polymerase III