Lipid-Induced Conformational Changes of an Integral Membrane Protein:  An Infrared Spectroscopic Study of the Effects of Triton X-100 Treatment on the Purple Membrane of <i>Halobacterium halobium</i> ET1001

Barnett, Steven M.; Dracheva, Swetlana; Hendler, Richard W.; Levin, Ira W.

doi:10.1021/bi952258l

Cited by 38 publications

(37 citation statements)

References 69 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As shown, the predominant bands centered at 1652 cm −1 relative to the amide I region and at 1545 cm −1 relative to the amide II region were both found to decrease in the bioconjugates, but the position of the bands are almost unchanged. The broad band at 1454 cm −1 assigned as δ CH of CH 2 groups [33] becomes sharper at 1464 cm −1 in the bioconjugates. The band at 1398 cm −1 due to COO − of aspartic acid (Asp) and glutamic acid (Glu) residues [33] almost disappear in the bioconjugates.…”

Section: Resultsmentioning

confidence: 92%

“…The broad band at 1454 cm −1 assigned as δ CH of CH 2 groups [33] becomes sharper at 1464 cm −1 in the bioconjugates. The band at 1398 cm −1 due to COO − of aspartic acid (Asp) and glutamic acid (Glu) residues [33] almost disappear in the bioconjugates. Casein consists of a highly repetitive sequence of amino acids of Asp and Glu (17% Asp and 23% Glu of all residues in casein).…”

Section: Resultsmentioning

confidence: 92%

See 1 more Smart Citation

The interaction between casein micelles and gold nanoparticles

Liu¹,

Guo²

2009

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 92%

Section: Resultsmentioning

confidence: 92%

The interaction between casein micelles and gold nanoparticles

Liu¹,

Guo²

2009

Journal of Colloid and Interface Science

View full text Add to dashboard Cite

“…However, because the cells do not synthesize retinal, an alternative role for the actinorhodopsin apoprotein cannot be ruled out. Many microbial rhodopsins oligomerize in the membrane and form large aggregates (55)(56)(57)(58)(59)(60). Without a cofactor, actinorhodopsin might still aggregate in the membrane, providing structural stability against membrane stresses.…”

Section: Discussionmentioning

confidence: 99%

Characterization of an Unconventional Rhodopsin from the Freshwater Actinobacterium Rhodoluna lacicola

2015

View full text Add to dashboard Cite

Rhodopsin-encoding microorganisms are common in many environments. However, knowing that rhodopsin genes are present provides little insight into how the host cells utilize light. The genome of the freshwater actinobacterium Rhodoluna lacicola encodes a rhodopsin of the uncharacterized actinorhodopsin family. We hypothesized that actinorhodopsin was a light-activated proton pump and confirmed this by heterologously expressing R. lacicola actinorhodopsin in retinal-producing Escherichia coli. However, cultures of R. lacicola did not pump protons, even though actinorhodopsin mRNA and protein were both detected. Proton pumping in R. lacicola was induced by providing exogenous retinal, suggesting that the cells lacked the retinal cofactor. We used high-performance liquid chromatography (HPLC) and oxidation of accessory pigments to confirm that R. lacicola does not synthesize retinal. These results suggest that in some organisms, the actinorhodopsin gene is constitutively expressed, but rhodopsin-based light capture may require cofactors obtained from the environment. IMPORTANCEUp to 70% of microbial genomes in some environments are predicted to encode rhodopsins. Because most microbial rhodopsins are light-activated proton pumps, the prevalence of this gene suggests that in some environments, most microorganisms respond to or utilize light energy. Actinorhodopsins were discovered in an analysis of freshwater metagenomic data and subsequently identified in freshwater actinobacterial cultures. We hypothesized that actinorhodopsin from the freshwater actinobacterium Rhodoluna lacicola was a light-activated proton pump and confirmed this by expressing actinorhodopsin in retinalproducing Escherichia coli. Proton pumping in R. lacicola was induced only after both light and retinal were provided, suggesting that the cells lacked the retinal cofactor. These results indicate that photoheterotrophy in this organism and others may require cofactors obtained from the environment. Rhodopsin-containing photoheterotrophic microbes are common inhabitants of marine, terrestrial, and freshwater environments, where they have been identified by cultivation (1-3), metagenomic sequencing (4-6), targeted amplicon sequencing (7-9), and quantitative PCR (9, 10). The cosmopolitan distribution of rhodopsin-containing microbes in diverse habitats is reflected in the variety of effects the rhodopsins have on their hosts. For instance, certain rhodopsins transport protons or other ions, while others affect gene expression through signaling networks (11). Within a single organism, multiple rhodopsins can be present and perform different roles (12, 13). Closely related rhodopsin-containing organisms have been shown to react to light differently: in Dokdonia spp., light exposure has been shown to provide a growth advantage for one species while offering no measurable benefit to another (14-16). In addition, rhodopsins may differ in their maximum absorption peaks (480 to 560 nm [17]) or their abilities to bind additional carotenoids (18,19) ...

show abstract

“…Moreover, cholesterol or similar molecule-rich membrane domains are reported to be more tolerant toward detergents such as TX100 molecules in comparison to other parts of the lipid bilayer. (8)(9)(10)(11)(12)(13)(14).…”

mentioning

confidence: 99%

Triton X-100 concentration effects on membrane permeability of a single HeLa cell by scanning electrochemical microscopy (SECM)

Koley

Bard

2010

Proc. Natl. Acad. Sci. U.S.A.

351

249

View full text Add to dashboard Cite

Changes in HeLa cell morphology, membrane permeability, and viability caused by the presence of Triton X-100 (TX100), a nonionic surfactant, were studied by scanning electrochemical microscopy (SECM). No change in membrane permeability was found at concentrations of 0.15 mM or lower during an experimental period of 30 to 60 min. Permeability of the cell membrane to the otherwise impermeable, highly charged hydrophilic molecule ferrocyanide was seen starting at concentrations of TX100 of about 0.17 mM. This concentration level of TX100 did not affect cell viability. Based on a simulation model, the membrane permeability for ferrocyanide molecules passing though the live cell membrane was 6.5 ± 2.0 × 10 -6 m/s. Cells underwent irreversible permeabilization of the membrane and structural collapse when the TX100 concentration reached the critical micelle concentration (CMC), in the range of 0.19 to 0.20 mM. The impermeability of ferrocyanide molecules in the absence of surfactant was also used to determine the height and diameter of a single living cell with the aid of the approach curve and probe scan methods in SECM.

show abstract

Lipid-Induced Conformational Changes of an Integral Membrane Protein: An Infrared Spectroscopic Study of the Effects of Triton X-100 Treatment on the Purple Membrane of Halobacterium halobium ET1001

Cited by 38 publications

References 69 publications

The interaction between casein micelles and gold nanoparticles

The interaction between casein micelles and gold nanoparticles

Characterization of an Unconventional Rhodopsin from the Freshwater Actinobacterium Rhodoluna lacicola

Triton X-100 concentration effects on membrane permeability of a single HeLa cell by scanning electrochemical microscopy (SECM)

Contact Info

Product

Resources

About