Atomic Force Microscopy of Cholera Toxin B-oligomers Bound to Bilayers of Biologically Relevant Lipids

Mou, Jianxun; Yang, Jie; Shao, Zongshu

doi:10.1006/jmbi.1995.0238

Cited by 180 publications

(128 citation statements)

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“…Although the resolution in AFM is not well defined and is strongly dependent on the nature of the specimen [26,28], the smallest surface features resolvable in these images suggest a spatial resolution of 10 A or better. For example, the end of the 'spike' near the central channel has a width of 8-10 ,~, representing one of the highest resolution AFM images achieved so far [28][29][30], which is significantly higher than that achieved with EM of two-dimensional crystals [18]. Based on these images, the GroES heptamer can be described as having a dome surface with a central protrusion (crown), which can be better appreciated in a surface plot (see Fig.…”

Section: Resultsmentioning

confidence: 94%

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

et al. 1996

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Using atomic force microscopy (AFM) in aqueous solution, we show that the surface structure of the oligomeric GroES can be obtained up to 10 A resolution. The seven subunits of the heptamer were well resolved without image averaging. The overall dimension of the GroES heptamer was 8.4+0.4 nm in diameter and 3.0+0.3 nm high. However, the AFM images further suggest that there is a central protrusion of 0.8+0.2 nm high and 4.5+0.4 nm in diameter on one side of GroES which displays a profound seven-fold symmetry. It was found that GroEL could not bind to the adsorbed GroES in the presence of AMP-PNP and Mg 2+, suggesting that the side of GroES with the central protrusion faces away from the GroEL lumen, because only one side of GroES was observed under these conditions. Based on the results from both electron and atomic force microscopy, a surface model for the GroES is proposed.Key words: Atomic force microscopy; GroES; GroEL; Resolution subunits were not discernible [18]. Because of the variable conformations observed by EM, it was even suggested that GroES could have a flexible structure or a symmetry other than the seven-fold [18]. Since the atomic force microscopy (AFM) has been shown to be capable of obtaining high resolution surface structures of several oligomeric bacterial proteins (for recent reviews, see [24][25][26]), we have applied this method to determine the surface structure of GroES under aqueous solutions. We show that the subunit structure can be clearly resolved in the AFM images without image processing/averaging. Surface structures beyond the subunits were also resolved, demonstrating a surface resolution of 10 A or so, which is much higher than that from EM images. In combination with the results from EM, a model for the GroES is also proposed. Materials and methods

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Section: Resultsmentioning

confidence: 94%

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

et al. 1996

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“…and this potential was recently demonstrated with several protein specimens at 1-2 nm resolution [7][8][9][10]. However.…”

Section: Introductionmentioning

confidence: 99%

High‐resolution atomic‐force microscopy of DNA: the pitch of the double helix

Mou

Czajkowsky²,

Zhang³

et al. 1995

FEBS Letters

178

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Using a cationic lipid bilayer, we show that DNA can be reliably adsorbed to the bilayer surface for atomic force microscopy (AFM) in aqueous buffers at high resolution. The measured width of the dsDNA is close to 2 nm, and a periodic modulation on dsDNA is reproducibly detected by the AFM. The measured period is 3.4 ± 0.4 nm, in excellent agreement with the known pitch of the double helix. The right-handedness of the double helix is directly discernible in high resolution AFM images. Thus, this approach can be readily applied to the study of DNA-protein interactions, as well as sequence mapping at high resolution.

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“…These domains were higher by 0.6 ± 0.2 nm than the black matrix. In the literature [12], gel phase domain was reported to be about 1 nm higher than liquid crystalline phase. Thus, the small domains are considered to be gel phase domains.…”

Section: Observation Of the Phase-separated Structuresmentioning

confidence: 96%

Effects of Applied Voltage on the Size of Phase-Separated Domains in DMPS-DOPC Lipid Binary Bilayers Supported on SiO<sub>2</sub>/Si Substrates

Yamauchi

Ujihara

Tero

et al. 2009

Trans. Mat. Res. Soc. Japan

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Supported lipid bilayers (SLB) are expected to offer a potential as biological devices utilizing biological membranes and membrane proteins. In this work, we investigated the effect of an external DC field on the phase-separated structures of gel phase and liquid crystalline phase in the SLBs of the DMPS-DOPC binary systems. The electric field was vertically applied to the SLB using a three-electrode system. The voltage apply of −1.0 V at the backside of the SLB increased the gel-phase domain size, while the voltage apply of +1.0 V decreased the domain size. This electric field effect is strongly related with the existence of PS lipids that is a negatively-charged lipid. Previously it was reported that the size of brain-PS-rich domain depends on the Ca 2+ concentration. This implies that it is possible to change the domain size due to the change of the Ca 2+ concentration near the surface of the SLB by applying the electric field.

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Atomic Force Microscopy of Cholera Toxin B-oligomers Bound to Bilayers of Biologically Relevant Lipids

Cited by 180 publications

References 0 publications

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

High resolution surface structure of E. coli GroES oligomer by atomic force microscopy

High‐resolution atomic‐force microscopy of DNA: the pitch of the double helix

Effects of Applied Voltage on the Size of Phase-Separated Domains in DMPS-DOPC Lipid Binary Bilayers Supported on SiO<sub>2</sub>/Si Substrates

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