Rhodopsin of 239 aas and 9 TMSs. This rhodopsin is from the thermophilic eubacterium Rubrobacter xylanophilus DSM 9941(T) and was isolated from thermally polluted water. Although R. xylanophilus rhodopsin (RxR) is from an Actinobacterium, it is located between eukaryotic and archaeal rhodopsins in the phylogenetic tree (Kanehara et al. 2017). E. coli cells expressing RxR showed a light-induced decrease in environmental pH and inhibition by a protonophore, indicating that it works as a light-driven outward proton pump. Purified RxR has an absorption maximum at 541 nm and binds all-trans retinal. The pKa values for the protonated retinal Schiff base and its counterion were 10.7 and 1.3, respectively. Of note, RxR showed an extremely high thermal stability in comparison with other proton pumping rhodopsins such as thermophilic rhodopsin TR (by 16-times) and bacteriorhodopsin from Halobacterium salinarum (HsBR, by 4-times) (Kanehara et al. 2017).
|Species:||Rubrobacter xylanophilus (strain DSM 9941 / NBRC 16129)  |
1: MEALWLWIGF VGMLLGTLYF AFLLTNAPEG TRYFFVITAT ITGIAAIAYL VMATGSGSTV
61: LPDGREFYWA RYIDWVITTP LLLLDLCLLA LADPRRNVTF IASLIALDVV MILTGLWAGA
121: TVNVAGRAIL FIISTAAFIG VLYLLVSRLF AEASRRTPAV AQIFRTLAVL TIVLWICYPI
181: VWLIGTEGFG AVSLSVEVFL FMVLDLLAKV GFGLLLLSSR QALSDIGSGA VAGTARRVA