High impact information on bop

• When transformed with this plasmid, a bop- insertion mutant of H. halobium yielded purple (Pum+) colonies [1].
• The insertion at the chromosomal bop locus remained intact in transformed cells, indicating that the plasmid bop gene was responsible for the Pum+ phenotype. bR was induced in early stationary phase in both wild-type and transformed cells [1].
• Integration of ura3 at the bacterioopsin locus (bop ) of this mutant restored 5-FOA sensitivity and uracil prototrophy [2].
• A shuttle vector containing a bop-hop-cartridge was transformed into a HR-deficient strain and blueish-coloured transformants were obtained [3].
• The bop promoter expressed HR to an extent where a specific membrane fraction resembled the crystalline purple membrane of BR in terms of the lipid to protein ratio [3].

Biological context of bop

• Employing a gene fusion approach, the promoter for the bop gene was used to drive expression of the hop gene [3].
• In mutant ET1001, bop gene cluster transcript levels did not increase above the highest levels obtained in the dark [4].
• Next, the bop promoter region was cloned on an H. halobium plasmid vector and introduced into NRC-1 and S9, a bop overproducer strain [5].
• Transcription from the bop promoter on the plasmid was found to be inhibited by novobiocin to a similar extent as was transcription from the chromosome [5].
• Deletion analysis of the cloned bop promoter from a site approximately 480 bp upstream of bop showed that a 53-bp region 5' to the transcription start site is sufficient for transcription, but a 28-bp region is not [5].

Associations of bop with chemical compounds

• To demonstrate ura3-based gene replacement, a Deltabop strain was constructed by transforming a Deltaura3 host with a bop deletion plasmid containing a mevinolin resistance marker [2].
• Indeed, transcription was induced, suggesting that the bop gene cluster is not completely uncoupled from regulation by oxygen tension in the bacterioruberin mutant [6].
• The bop gene codes for the membrane protein bacterio-opsin (BO), which on binding all-trans-retinal, constitutes the light-driven proton pump bacteriorhodopsin (BR) in the archaebacterium Halobacterium salinarium [7].

Regulatory relationships of bop

• From these data, we propose a regulatory model involving two different mechanisms: (i) bat gene expression is induced under conditions of low oxygen tension and the bat gene product activates bop gene expression and (ii) light induces brp transcription, which stimulates or modulates bat transcription [6].

Other interactions of bop

• When the cloned promoter was introduced into S9 mutant strains with insertions in either of two putative regulatory genes, brp and bat, no transcription was detectable, indicating that these genes serve to activate transcription from the bop promoter in trans [5].

References