Disease relevance of imm

• This homology, denoted Hs, was revealed by electron microscopic examination of lambda imm lambda/lambda imm21 and lambda imm434/lambda imm21 heteroduplexes, and permitted us to construct a special lambda hybrid (lambda hyB) which contains the N region of phage 21 and the adjacent imm region from phage 434 [1].
• Downstream from its colicin and immunity genes (col. imm), Escherichia coli plasmid ColE3-CA38 contains a 0.81-kb DNA segment, the hic region, which is required for high colicin production [2].

High impact information on imm

• The imm gene of plasmid ColE2-P9 is 255 bp long and is separated from the end of the col gene by a dinucleotide [3].
• Using the M13 dideoxy sequencing technique, we have established the DNA sequences of colicins E2 and E3 which encompass the receptor-binding and the catalytic domains of each of the nucleases, and their immunity (imm) genes [3].
• However, pVT25 can be maintained within the Escherichia coli cells when complemented with another plasmid, pVT26, which expresses the colicin E3 immunity (imm) and the TcR phenotypes [4].
• The nucleotide sequence of the 0.81-kb region was determined and the hic gene localized to its imm-distal portion following an open reading frame (ORF) with no known function [2].
• Location of the abi, col and imm genes on pHU011, a colicin Ib plasmid derivative [5].

Chemical compound and disease context of imm

• Ethanol treatment of the starting cells also produced a 5- to 18-fold increase in the occurrence of E. coli pgl mutations, which likely arose by the deletion mechanism generating the imm lambda defects, since pgl was closely linked to the integrated lambda fragment [6].

Biological context of imm

• (2) These HindIII sites are flanked by selectable markers with the following phenotypes: Spi+/- (Fec+/-) to the left, and imm lambda or imm434 to the right [7].
• Consistent with this hypothesis, it was found that imm gene transcription increased severalfold in vitro when the chromosome was cleaved in a way that eliminated transcription originating at the col gene promoter [8].
• From the DNA sequence of the chromosome, it was concluded that the transcripts from the imm and col genes must crisscross each other over a region of about 75 base pairs [8].
• The imm lambda p lambda CM1 replicon does not show the same incompatibility behavior [9].
• The probable reason that lambda imm21 phages show such altered phenotypes when carrying a functional plasmid replication origin, whereas lambda imm lambda and lambda imm434 (Mukai et al., 1978) phages do not, is the relative ease of titration of the phage 21 repressor to allow transcription from pR21 [10].

Associations of imm with chemical compounds

• Ethanol treatment of starting cells increased the occurrence of imm lambda-defective clones to near 100% [6].
• The entire immunity gene operon was also cloned under the control of the tac promoter, generating pTCU2, which, upon induction with isopropyl beta-D-thiogalactopyranoside, produced the imm gene product in amounts sufficient to be visualized by autoradiography [11].

Regulatory relationships of imm

• The colicin Ib (ColIb) plasmid genes that inhibit the replication of the T5-like and T7 bacteriophage have been cloned on an approximately 7200-bp ClaI fragment and their sites relative to each other and to the colicin immunity (imm) gene have been mapped [12].

Analytical, diagnostic and therapeutic context of imm

• The protective action of immunity protein is a unique aspect of the colicin problem, and information has been obtained, by genetic techniques, about the probable membrane topography of the imm gene product [13].

References