A Study on Sensory Rhodopsins from a Native Halobacterium Isolated from Taiwan
Date Issued
2015
Date
2015
Author(s)
Chen, Pei-Chun
Abstract
Studies in proteins from local species offer valuable information in biological diversity. The main aim of this study was to investigate whether microbial rhodopsins in haloarchaea from Taiwan exhibit a region-dependent adaptation. To achieve this goal, we first tried to isolate local haloarchaea and proved them to be a new species, then microbial rhodopsins from it were cloned for bioinformatic, biochemical and biophysical studies before we attempted to compare their differences with other known microbial rhodopsins. In a previous study, we have isolated a haloarchaea from Beiman saltern in southern Taiwan and and identified it as a new strain; it was temporarily named as Ht. In this study, further growth condition experiments suggested Ht as a new strain; we therefor name it Haloarcula taiann. A total of four microbial rhodopsins were successfully cloned and sequenced from Ht. Protein sequence alignment showed only 87-93% similarity to any known microbial rhodopsins; it further supported H. taiann as a new species. Among those four rhodopsins, we found sensory rhodopsin I, HtSRI, to be unusually more stable and was surprisingly responsive to light of > 650 nm, a feature not being observed in any other know SRI proteins. In addition to biological, biochemical and biophysical studies, we also tried to grow protein crystal, a procedure failed in all other SRI due to stability issue. Since SRI is the only microbial rhodopsin that still lacks atomic structure, we have list it as a goal in this study. We expected that solving protein structure for HtSRI can shine light on protein science. We also cloned its transducer, a cognate partner protein when SRI exerting positive phototaxis, and engineered them together as another strategy to further stabilize HtSRI for crystallographic study. Hence all the evidences supported H. taiwanenesis a new species from Taiwan, we further conducted whole genomic sequencing and gene annotation. Now we have obtained all the rhodopsins exiting in H. taiwanenesis and full length gene sequences.
Subjects
haloarchaea
Haloarcula
senosory rhodopsin
phototaxis
photocycle
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-104-R02b22053-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):8b7b554240f3db58f84cb9ce71aebde4