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Bacterioopsin-triggered retinal biosynthesis is inhibited by bacteriorhodopsin formation in Halobacterium salinarium

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Title Bacterioopsin-triggered retinal biosynthesis is inhibited by bacteriorhodopsin formation in Halobacterium salinarium
 
Creator DESHPANDE, A
SONAR, S
 
Subject purple membrane
opsin gene
escherichia-coli
mechanism
transport
halobium
fusion
transfection
expression
liposomes
 
Description Factors regulating retinal biosynthesis in halobacteria are not clearly understood. In halobacteria, events leading to the biosynthesis of bacteriorhodopsin have been proposed to participate in stringent regulation of retinal biosynthesis, The present study describes a novel approach of in vivo introductions of mRNA and membrane proteins via liposome fusion to test their role in cellular metabolism. Both the bacterioopsin-encoding mRNA and the liposome-encapsulated bacterioopsin (apoprotein) are independently introduced in spheroplasts of the purple membrane-negative strain Halobacterium salinarium that initially contain neither bacterioopsin nor retinal, Isoprenoid analyses of these cells indicate that the expression/presence of bacterioopsin triggers retinal biosynthesis from lycopene, and its subsequent binding to opsin generates bacteriorhodopsin, When bacteriorhodopsin and excess retinal were independently introduced into spheroplasts of purple membrane-negative cells, the introduction of bacteriorhodopsin resulted in an accumulation of lycopene, indicating an inhibition of retinal biosynthesis, These results provide direct evidence that the formation of bacterioopsin acts as a trigger for lycopene conversion to beta-carotene in retinal biosynthesis. The trigger for this event does not lie with either transcription or translation of the bop gene, It is clearly associated with the folded and the membrane-integrated state of bacterioopsin. On the other hand, the trigger signaling inhibition of retinal biosynthesis does not lie with the presence of excess retinal but with the correctly folded, retinal-bound form, bacteriorhodopsin.
 
Publisher AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
 
Date 2011-07-17T04:33:31Z
2011-12-26T12:50:07Z
2011-12-27T05:36:07Z
2011-07-17T04:33:31Z
2011-12-26T12:50:07Z
2011-12-27T05:36:07Z
1999
 
Type Article
 
Identifier JOURNAL OF BIOLOGICAL CHEMISTRY, 274(33), 23535-23540
0021-9258
http://dx.doi.org/10.1074/jbc.274.33.23535
http://dspace.library.iitb.ac.in/xmlui/handle/10054/4616
http://hdl.handle.net/10054/4616
 
Language en