Characterization of a second gene involved in bacterio-opsin gene expression in a halophilic archaebacterium

Leong, D; Pfeifer, Felicitas; Boyer, Herbert W.; Betlach, Mary C.

doi:10.1128/jb.170.10.4903-4909.1988

Cited by 35 publications

(38 citation statements)

References 32 publications

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“…1) that includes bop, which encodes BO; bat, which encodes a transacting factor (Bat) that contains a region homologous to the PAS domain of the oxygen sensor NifL (19,20) and activates bop expression under microaerobic conditions (21,22); and blp, a gene of unknown function (23). Insertions in brp greatly decrease BR and bop mRNA levels (15)(16)(17)(18). This result can be interpreted to imply that Brp modulates bop expression (18,21).…”

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confidence: 93%

“…However, cellular factors may be required to prevent the photooxidation or photoisomerization of the cofactor during its transport or binding to BO. These functions may be mediated by a retinal-specific chaperone or by a multifunctional enzyme that converts ␤-carotene to retinal and transports or binds retinal to BO.As a first step to identify cellular factors that mediate these processes, we chose to study the brp gene, which encodes a putative membrane protein (Brp) implicated in BR biogenesis (15)(16)(17)(18). The brp gene is part of a gene cluster (Fig.…”

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confidence: 99%

“…As a first step to identify cellular factors that mediate these processes, we chose to study the brp gene, which encodes a putative membrane protein (Brp) implicated in BR biogenesis (15)(16)(17)(18). The brp gene is part of a gene cluster (Fig.…”

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brp and blh Are Required for Synthesis of the Retinal Cofactor of Bacteriorhodopsin in Halobacterium salinarum

Peck

Echávarri-Erasun²,

Johnson

et al. 2001

Journal of Biological Chemistry

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Bacteriorhodopsin, the light-driven proton pump of Halobacterium salinarum, consists of the membrane apoprotein bacterioopsin and a covalently bound retinal cofactor. The mechanism by which retinal is synthesized and bound to bacterioopsin in vivo is unknown. As a step toward identifying cellular factors involved in this process, we constructed an in-frame deletion of brp, a gene implicated in bacteriorhodopsin biogenesis. In the ⌬brp strain, bacteriorhodopsin levels are decreased ϳ4.0-fold compared with wild type, whereas bacterioopsin levels are normal. The probable precursor of retinal, ␤-carotene, is increased ϳ3.8-fold, whereas retinal is decreased by ϳ3.7-fold. These results suggest that brp is involved in retinal synthesis. Additional cellular factors may substitute for brp function in the ⌬brp strain because retinal production is not abolished. The in-frame deletion of blh, a brp paralog identified by analysis of the Halobacterium sp. NRC-1 genome, reduced bacteriorhodopsin accumulation on solid medium but not in liquid. However, deletion of both brp and blh abolished bacteriorhodopsin and retinal production in liquid medium, again without affecting bacterioopsin accumulation. The level of ␤-carotene increased ϳ5.3-fold. The simplest interpretation of these results is that brp and blh encode similar proteins that catalyze or regulate the conversion of ␤-carotene to retinal.Rhodopsins are integral membrane proteins containing seven transmembrane ␣-helices and a covalently bound molecule of retinal. Two distinct rhodopsin families are known: the visual rhodopsins, which bind 11-cis retinal or related compounds and function as photoreceptors in vertebrates (1) and invertebrates (2), and the archaeal rhodopsins, which bind all-trans-retinal and function as light-driven ion pumps and phototaxis receptors in archaea (3). Archaeal rhodopsin orthologs have been found recently in bacteria (4) and fungi (5), suggesting that retinal-based pigments are of widespread significance. Despite their importance, the biogenesis of these molecules is not fully understood. In particular, relatively little is known about how retinal is assembled with the opsin apoprotein in vivo. Thus, a goal in elucidating rhodopsin biogenesis is to identify the cellular factors that mediate the biosynthesis or uptake of retinal, the transport of retinal in the cell, and the binding of retinal to the corresponding opsin.To this end, we have studied the biogenesis of bacteriorhodopsin (BR), 1 a light-driven proton pump in the archaeon Halobacterium salinarum. BR consists of the membrane protein bacterioopsin (BO) and all-trans-retinal. Under microaerobic conditions, BR is induced ϳ50-fold (6) and forms a twodimensional crystal known as the purple membrane. This system has served as a model for studying key steps in membrane protein biogenesis, including protein insertion into the membrane (7,8) and the assembly of protein-lipid complexes (9, 10). H. salinarum is genetically tractable, and the genome sequence of a closely related organism, Halo...

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brp and blh Are Required for Synthesis of the Retinal Cofactor of Bacteriorhodopsin in Halobacterium salinarum

Peck

Echávarri-Erasun²,

Johnson

et al. 2001

Journal of Biological Chemistry

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“…Three genes important for purple membrane synthesis have been identified on the H. halobium chromosome: bop, specifying the purple membrane apoprotein (14), and two genes of possible regulatory function, brp (2) and bat (25) (6,8,21). Additionally, a nearly silent chromosomal gas vesicle locus has been identified (20,21 Initially, we analyzed H. halobium RNA isolated from batch cultures grown under standard laboratory conditions (9), which show the highest levels of purple membrane and gas vesicles at stationary phase (22,38).…”

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Transcriptional induction of purple membrane and gas vesicle synthesis in the archaebacterium Halobacterium halobium is blocked by a DNA gyrase inhibitor

Yang

DasSarma

1990

J Bacteriol

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We have investigated the expression of the bacteriorhodopsin gene (bop) and the gas vesicle protein gene (gvpA) in the extremely halophilic archaebacterium Halobacterium halobium, using primer-directed reverse transcription of RNA to quantify message levels. The level of gvpA gene transcript was found to increase about 5-fold from early to mid-logarithmic growth phase, while the level of bop gene transcript increased about 20-fold from mid-logarithmic to stationary phase. Transcriptional induction of both the gvpA and bop genes was significantly reduced by aeration and almost completely blocked by the DNA gyrase inhibitor novobiocin.

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“…Another deletion event was characterized that affects the upstream region of the bop gene in Bop mutant M86, in which * Corresponding author. recombination between 8-base-pair (bp) repeats leads to deletion of the intervening 1,883 bp of DNA (9).…”

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Insertion elements and deletion formation in a halophilic archaebacterium

Pfeifer

Blaseio

1989

J Bacteriol

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Deletion events that occur spontaneously in 36-kilobase-pair (kbp) plasmid pHH4 from the archaebacterium Halobacterium halobium were investigated. Four different deletion derivatives with sizes ranging from 5.7 to 17 kbp were isolated. Three of these deletion variants derived from pHH4 (pHH6 [17 kbp], pHH7 [16 kbpJ, and pHH8 [6.3 kbpJ), whereas the 5.7-kbp plasmid pHH9 derived from pHH6. Strains containing pHH6, pHH7, or pHH9 each lacked the parental plasmid pHH4, while pHH8 occurred at a 1:1 ratio together with p4H4. Common to all of these plasmids was the 5.7-kbp region of pHH9 DNA. The regions containing the fusion site in the deletion derivatives were investigated and compared with the corresponding area of the parental plasmid. Each deletion occurred exactly at the terminus of an insertion element. In pHH6 and pHH7, a halobacterial insertion element (ISH2) was located at the deletion site. The DNA fused to ISH2 displayed a 7-base-pair (bp) (pHH7) or 10-bp (pHH6) sequence homology to the inverted repeat of ISH2. In the two smaller plasmids, pHH8 and pHH9, an ISH27 element was located at the deletion site. Most likely, all of these smaller plasmids resulted from an intramolecular transposition event. The ISH27 insertion sequence contains a 16-bp terminal inverted repeat and duplicates 5 bp of target DNA during the transposition with the specificity 5'ANNNT3'. Four ISH27 copies were analyzed, and two ISH27 element types were identified that have approximately 85% sequence similarity. The ISH27 insertion elements constitute a family which is related to the ISH51 family characterized for H. volcanii, another halophilic archaebacterium.

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Characterization of a second gene involved in bacterio-opsin gene expression in a halophilic archaebacterium

Cited by 35 publications

References 32 publications

brp and blh Are Required for Synthesis of the Retinal Cofactor of Bacteriorhodopsin in Halobacterium salinarum

brp and blh Are Required for Synthesis of the Retinal Cofactor of Bacteriorhodopsin in Halobacterium salinarum

Transcriptional induction of purple membrane and gas vesicle synthesis in the archaebacterium Halobacterium halobium is blocked by a DNA gyrase inhibitor

Insertion elements and deletion formation in a halophilic archaebacterium

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