Nucleotide sequence analysis of the purEK operon encoding 5'-phosphoribosyl-5-aminoimidazole carboxylase of Escherichia coli K-12.
5'-Phosphoribosyl-5-aminoimidazole (AIR) carboxylase (EC 4.1.1.21) catalyzes step 6, the carboxylation of AIR to 5'-phosphoribosyl-5-aminoimidazole-4-carboxylic acid, in the de novo biosynthesis of purine nucleotides. As deduced from the DNA sequence of restriction fragments encoding AIR carboxylase and supported by maxicell analyses, AIR carboxylase was found to be composed of two nonidentical subunits. In agreement with established complementation data, the catalytic subunit (deduced Mr, 17,782) was encoded by the purE gene, while the CO2-binding subunit (deduced Mr, 39,385) was encoded by the purK gene. These two genes formed an operon in which the termination codon of the purE gene overlapped the initiation codon of the purK gene. The 5' end of the purEK mRNA was determined by mung bean nuclease mapping and was located 41 nucleotides upstream of the proposed initiation codon. The purEK operon is regulated by the purR gene product, and a purR regulatory-protein-binding site related to the sequences found in other pur loci was identified in the purEK operon control region.
Tiedeman
A A
AA
Seattle Biomedical Research Institute, Washington 98109.
Keyhani
J
J
Kamholz
J
J
Daum
H A
HA
Gots
J S
JS
Smith
J M
JM
D000595:Amino Acid Sequence; D001483:Base Sequence; D002262:Carboxy-Lyases / Q000235:genetics*; D004269:DNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics*; D005796:Genes; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009876:Operon; D012329:RNA, Bacterial / Q000235:genetics / Q000302:isolation & purification; D012333:RNA, Messenger / Q000235:genetics; D015183:Restriction Mapping; D012689:Sequence Homology, Nucleic Acid; D013045:Species Specificity; D014158:Transcription, Genetic
D004269:DNA, Bacterial; D012329:RNA, Bacterial; D012333:RNA, Messenger; D002262:Carboxy-Lyases; C022378:phosphoribosylaminoimidazole carboxylase