BACTERIOOPSIN, HALOOPSIN, AND SENSORY OPSIN-I OF THE HALOBACTERIAL ISOLATE HALOBACTERIUM SP STRAIN-SG1 - 3 NEW MEMBERS OF A GROWING FAMILY

Citation
J. Soppa et al., BACTERIOOPSIN, HALOOPSIN, AND SENSORY OPSIN-I OF THE HALOBACTERIAL ISOLATE HALOBACTERIUM SP STRAIN-SG1 - 3 NEW MEMBERS OF A GROWING FAMILY, Journal of bacteriology, 175(9), 1993, pp. 2720-2726
Citations number
54
Categorie Soggetti
Microbiology
Journal title
ISSN journal
00219193
Volume
175
Issue
9
Year of publication
1993
Pages
2720 - 2726
Database
ISI
SICI code
0021-9193(1993)175:9<2720:BHASOO>2.0.ZU;2-#
Abstract
The genes coding for bacterioopsin, haloopsin, and sensory opsin I of a halobacterial isolate from the Red Sea called Halobacterium sp. stra in SG1 have been cloned and sequenced. The deduced protein sequences w ere aligned to the previously known halobacterial retinal proteins. Th e addition of these new sequences lowered the number of conserved resi dues to only 23 amino acids, or 8% of the alignment. Data base searche s with two highly conserved peptides as well as with an alignment prof ile yielded no significant similarity to any other protein, so the hal obacterial retinal proteins should be regarded as a distinct protein f amily. The protein alignment was used to make predictions about the st ructure of the retinal proteins as well as about the amino acids in co ntact with retinal proteins. These results were in excellent agreement with the structural model of bacteriorhodopsin of Halobacterium halob ium as well as with mutant studies, indicating that (i) structure pred ictions based on the sequences of a membrane protein family can be qui te accurate; (ii) halorhodopsin and sensory rhodopsin I have tertiary structures similar to that of bacteriorhodopsin; (iii) conserved amino acids do not take part in reactions specific for one group of protein s, e.g., proton translocation for bacteriorhodopsins, but have a cruci al role in determining the conformation and reactions of the chromopho re; and (iv) the general mode of action (light-induced chromophore and protein movements) is the same for all halobacterial retinal proteins , ion pumps as well as sensors.