Salmonella typhimurium purB encodes adeny-losuccinate lyase (ASL), the enzyme that catalyzes step 8 in the pathway for de novo synthesis of inosine 5’-monophos-phate (IMP) and also the final reaction in the two-step ...Salmonella typhimurium purB encodes adeny-losuccinate lyase (ASL), the enzyme that catalyzes step 8 in the pathway for de novo synthesis of inosine 5’-monophos-phate (IMP) and also the final reaction in the two-step sequence from IMP to adenosine monophosphate (AMP). The nucleotide sequence ofpurB was obtained by the genetic map and sequence homologous analysis. The conserved pur operator in purB was identified to be located 185 bp downstream of the initiation codon and overlaps codons 62 - 67 in the protein-coding region. The binding of PurR to this operator was demonstrated by gel retardation experiment and site-directed mutagenesis, indicating that the purB is under the control of purR. We also answered why previous study had conflicting report concerning the regulation of purB by purR by identifying the junction site of purB to lacZ in a purB-MudJ (lacZ, Kan’) fusion strain. This result strongly supports that the purB is the second gene in the ycfC-purB operon.展开更多
基金Thiswork was supported by the National Natural Science Foundation of China.
文摘Salmonella typhimurium purB encodes adeny-losuccinate lyase (ASL), the enzyme that catalyzes step 8 in the pathway for de novo synthesis of inosine 5’-monophos-phate (IMP) and also the final reaction in the two-step sequence from IMP to adenosine monophosphate (AMP). The nucleotide sequence ofpurB was obtained by the genetic map and sequence homologous analysis. The conserved pur operator in purB was identified to be located 185 bp downstream of the initiation codon and overlaps codons 62 - 67 in the protein-coding region. The binding of PurR to this operator was demonstrated by gel retardation experiment and site-directed mutagenesis, indicating that the purB is under the control of purR. We also answered why previous study had conflicting report concerning the regulation of purB by purR by identifying the junction site of purB to lacZ in a purB-MudJ (lacZ, Kan’) fusion strain. This result strongly supports that the purB is the second gene in the ycfC-purB operon.
