You will see that regu-lation occurs at several points between the gene and the protein, and that regulatory mechanisms are more complex than those in prokaryotes. Study Break1. Suppose the lacI gene is mutated so that the Lac repressor is not made. How does this muta-tion aff ect the ...
The first described operon was the lactose operon in Escherichia coli, also commonly referred to as the lac operon [3]. How does the lac operon work? The lac operon is required for the transport and metabolism of lactose. The lacI gene is constitutively expressed, meaning that it is ...
The lacI gene encodes a repressor protein, LacI, that conditionally binds a DNA sequence (the lac operator) which has been constructed to overlap PT7 (bacteriophage T7 RNA polymerase transcriptional promoter). Briefly, at high temperature (42°C) without IPTG, the antisense promoter is active, ...
pCOLADuet-1 KanR,T7 promoter, ColA origin, lacI Novagen pCOLA-GFP The pCOLADuet-1 plasmid expression gfp gene This study pCOLA-119 The gfp gene under the control of J23119 promoter in pCOLADuet-1 This study 2.2. Medium and culture conditions E. coli strains were grown in Luria-Bertani (LB...
cell lysis. Additionally, the recombinant expression plasmid also contains the gene encoding Lac repressor LacI (38.6 kDa) fromE. coli33. Even though the LacI protein was successfully expressed in the cells, no protein band for LacI was detected in the supernatant (Fig. 2b). To exclude ...
Although the classic lac operon of E. coli consists of three ORFs (lacZYA), which are regulated by the product of the adjacent lacI repressor gene, bacteria containing only lacZY or lacZ have been identified[57–59]. While the evolutionary origin of the E. coli lac operon is uncertain[59...
λ DE3 = λ sBamHIo ∆EcoRI-B int::(lacI::PlacUV5::T7 gene1) i21 ∆nin5) from New England Biolabs were used for protein expression. Selection vector for DHFR constructs DHFR variants were cloned into a modified version of the pACYC-Duet 1 vector (Novagen), which we refer ...
Gene-disruption mutations indicated that both are required for immunity against lacticin RM. lacI encodes a small cationic protein, which is required for the production of and immunity to lacticin RM. Protection was obtained only when lacF, lacG and lacI were present together....
The T7 expression system harbors a second lacI gene sequence within its DE3 lysogen, which would, theoretically, double the LacI concentration per cell. The plasmid-based expression systems used in this study were based on the pET plasmid system, which encodes a second lacI gene sequence. In ...
Bbr_0530 (designated here as lntS) encodes a putative solute-binding protein of an ABC transporter system. Located immediately upstream of this cluster, Bbr_0526 (designated lntR) encodes a putative LacI-type transcriptional regulator. We have previously implicated the Bbr_0526-530 gene cluster, ...