Electrostatics Trigger Interfacial Self-Assembly of Bacterial Ice Nucleators

Madzharova, Fani; Bregnhøj, Mikkel; Chatterley, Adam S.; Løvschall, Kaja Borup; Drace, Taner; Dreyer, Lasse Sander Andersen; Boesen, Thomas; Weidner, Tobias

doi:10.1021/acs.biomac.1c01217

Cited by 9 publications

(6 citation statements)

References 46 publications

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“…Sum frequency generation (SFG) spectral data reveal enhanced structural ordering around the IBS of bacterial INPs. 45,46 Several theoretical and computational studies support this counsel. 47−49 Both INPs and AFPs are capable of inducing water structure formation in the hydration layer of their IBS, and then, the crucial question is what factors differentiate between them such that they exhibit opposing biological activities.…”

Section: Introductionmentioning

confidence: 72%

“…Sum frequency generation (SFG) spectral data reveal enhanced structural ordering around the IBS of bacterial INPs. , Several theoretical and computational studies support this counsel. − Both INPs and AFPs are capable of inducing water structure formation in the hydration layer of their IBS, and then, the crucial question is what factors differentiate between them such that they exhibit opposing biological activities. AFPs are soluble secretory proteins, and recently we have observed that the ability of AFPs to maintain a liquid-like hydration structure around the non-IBS is crucial to elicit the ice growth inhibition property. , On the other hand, the aggregation of INPs generates a large surface that acts as a suitable template for ice nucleation .…”

Section: Introductionmentioning

confidence: 98%

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Preferential Ordering and Organization of Hydration Water Favor Nucleation of Ice by Ice-Nucleating Proteins over Antifreeze Proteins

et al. 2023

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Bacteria containing ice-nucleating proteins (INPs) evolved in nature to nucleate ice at the high sub-zero ambiance. The ability of the INPs to induce order in the hydration layer and their aggregation propensity appear to be key factors of their ice nucleation abilities. However, the mechanism of the process of ice nucleation by INPs is yet to be understood clearly. Here, we have performed all-atom molecular dynamics simulations and analyzed the structure and dynamics of the hydration layer around the proposed ice-nucleating surface of a model INP. Results are compared with the hydration of a topologically similar non-ice-binding protein (non-IBP) and another ice-growth inhibitory antifreeze protein (sbwAFP). We observed that the hydration structure around the ice-nucleating surface of INP is highly ordered and the dynamics of the hydration water are slower, compared to the non-IBP. Even the ordering of the hydration layer is more evident around the ice-binding surface of INP, compared to the antifreeze protein sbwAFP. Particularly with increasing repeat units of INP, we observe an increased population of ice-like water. Interestingly, the distances between the hydroxyl groups of the threonine ladder and its associated channel water of the ice-binding surface (IBS) of INP in the X and Y direction mimic the oxygen atom distances of the basal plane of hexagonal ice. However, the structural synergies between the hydroxyl group distances of the threonine ladder and its associated channel water of the IBS of sbwAFP and oxygen atom distances of the basal plane are less evident. This difference makes the IBS of the INP a better template for ice nucleation than AFP, although both of them bind to the ice surface efficiently.

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Section: Introductionmentioning

confidence: 72%

Section: Introductionmentioning

confidence: 98%

Preferential Ordering and Organization of Hydration Water Favor Nucleation of Ice by Ice-Nucleating Proteins over Antifreeze Proteins

et al. 2023

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“…In the WO-coils, position 12 is usually occupied by residues of the opposite charge, Asp and Glu. This charge inversion is noteworthy as it has been shown that electrostatic interactions contribute to the formation of INP multimers (17, 18). It has also been shown that INP activity is affected by pH, which is consistent with a role for electrostatic interactions (19).…”

Section: Introductionmentioning

confidence: 85%

Ice nucleation proteins self-assemble into large fibres to trigger freezing at near 0 °C

Hansen,

Lee,

Reicher

et al. 2023

Preprint

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Ice nucleating bacteria like Pseudomonas borealis (Pb) can trigger frost formation at temperatures as high as -2 C. The efficiency of ice formation by these bacteria comes from the ability of their >100 kDa ice nucleation proteins (INPs) to form ~10 MDa multimers. The INP monomers contain an array of tandem repeats, each of which is predicted to form a single coil in a B-solenoid. The 12 coils at the C-terminal end of the INP differ from the other 53 coils in lacking water organizing motifs and by having arginines on one side of the solenoid in place of acidic residues. Here we show that these arginine-containing coils (R-coils) are a distinct subdomain that, along with the adjacent putative 41-residue capping structure, facilitate INP multimerization. Bioinformatic analyses show that the cap structure is highly conserved, as is the number of R-coils. Indeed, the loss of just a few R-coils eliminated ice-nucleation activity, as did mutations designed to spoil the fold of the capping structure. Movement of the R-coils to the N-terminal end or to the middle of the B-solenoid caused a large decrease in ice nucleation temperature. Replacing the arginines with acidic residues decreased the nucleation temperature. Activity was restored when these residues were in turn replaced by lysines. A role for electrostatic interactions in INP self-assembly was suggested by the effect of pH on ice nucleation activity in bacterial lysates. This activity declined by 3-6 C at pH values below 5.0. When the INP-producing E. coli were examined by cryo-electron tomography, the cell cytoplasm contained clusters of 100 to 200 nm-long and ~5 nm-wide fibres that were absent from control bacteria. Each fibre is wide enough to have up to two INPs in cross-section and is long enough to span several INPs end to end. The ice nucleation activity in the lysates was remarkably resistant to heat treatment up to ~70 C, above which there was a slight decline with increasing temperature. Even after heating to 99 C, the lysate ice nucleation activity only lost ~8 C. We suggest that the R-coils play a crucial role in INP fibre assembly and that a bundle of these fibers could amass a sufficient number of ice-like water molecules to initiate ice nucleation at high sub-zero temperatures.

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“…Transmission two-dimensional infrared (2D-IR) spectra were recorded using a commercial instrument set to operate in the amide I region (2DQuickIR, PhaseTech Spectroscopy), as described previously. 20 Briefly, a time delayed collinear pair of femtosecond infrared pump pulses were produced using a pulse shaper, and the transmission spectrum of the pumped sample was measured using a third, non-collinear, infrared pulse that was dispersed on a grating spectrometer and measured using a high repetition rate MCT detector (Jackhammer, PhaseTech Spectroscopy). Fourier transformation with respect to the delay between the pump pulses produced the 2D-IR spectra shown.…”

Section: Methodsmentioning

confidence: 99%

Structure and Orientation of the SARS-Coronavirus-2 Spike Protein at Air–Water Interfaces

et al. 2022

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The SARS coronavirus 2 (SARS-CoV-2) spike protein is located at the outermost perimeter of the viral envelope and is the first component of the virus to make contact with surrounding interfaces. The stability of the spike protein when in contact with surfaces plays a deciding role for infection pathways and for the viability of the virus after surface contact. While cryo-EM structures of the spike protein have been solved with high resolution and structural studies in solution have provided information about the secondary and tertiary structures, only little is known about the folding when adsorbed to surfaces. We here report on the secondary structure and orientation of the S1 segment of the spike protein, which is often used as a model protein for in vitro studies of SARS-CoV-2, at the air–water interface using surface-sensitive vibrational sum-frequency generation (SFG) spectroscopy. The air–water interface plays an important role for SARS-CoV-2 when suspended in aerosol droplets, and it serves as a model system for hydrophobic surfaces in general. The SFG experiments show that the S1 segment of the spike protein remains folded at the air–water interface and predominantly binds in its monomeric state, while the combination of small-angle X-ray scattering and two-dimensional infrared spectroscopy measurements indicate that it forms hexamers with the same secondary structure in aqueous solution.

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Electrostatics Trigger Interfacial Self-Assembly of Bacterial Ice Nucleators

Cited by 9 publications

References 46 publications

Preferential Ordering and Organization of Hydration Water Favor Nucleation of Ice by Ice-Nucleating Proteins over Antifreeze Proteins

Preferential Ordering and Organization of Hydration Water Favor Nucleation of Ice by Ice-Nucleating Proteins over Antifreeze Proteins

Ice nucleation proteins self-assemble into large fibres to trigger freezing at near 0 °C

Structure and Orientation of the SARS-Coronavirus-2 Spike Protein at Air–Water Interfaces

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