scholarly journals Recruitment of Class I Hydrophobins to the Air:Water Interface Initiates a Multi-step Process of Functional Amyloid Formation

2011 ◽  
Vol 286 (18) ◽  
pp. 15955-15963 ◽  
Author(s):  
Vanessa K. Morris ◽  
Qin Ren ◽  
Ingrid Macindoe ◽  
Ann H. Kwan ◽  
Nolene Byrne ◽  
...  
Keyword(s):  
Self Assembly ◽  
Structural Rearrangement ◽  
Class I ◽  
Amyloid Formation ◽  
Interface Properties ◽  
Functional Amyloid ◽  
Remarkable Case ◽  
Macromolecular Assembly ◽  
Insight Into

Class I fungal hydrophobins form amphipathic monolayers composed of amyloid rodlets. This is a remarkable case of functional amyloid formation in that a hydrophobic:hydrophilic interface is required to trigger the self-assembly of the proteins. The mechanism of rodlet formation and the role of the interface in this process have not been well understood. Here, we have studied the effect of a range of additives, including ionic liquids, alcohols, and detergents, on rodlet formation by two class I hydrophobins, EAS and DewA. Although the conformation of the hydrophobins in these different solutions is not altered, we observe that the rate of rodlet formation is slowed as the surface tension of the solution is decreased, regardless of the nature of the additive. These results suggest that interface properties are of critical importance for the recruitment, alignment, and structural rearrangement of the amphipathic hydrophobin monomers. This work gives insight into the forces that drive macromolecular assembly of this unique family of proteins and allows us to propose a three-stage model for the interface-driven formation of rodlets.

scholarly journals The Role of Proteins in Biosilicification

Scientifica ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-22 ◽  
Author(s):  
Daniel Otzen
Keyword(s):  
Self Assembly ◽  
Organic Matrix ◽  
Specific Protein ◽  
Colloidal Systems ◽  
Protein Properties ◽  
Modified Peptides ◽  
Fundamental Biology ◽  
Living Organisms ◽  
Insight Into

Although the use of silicon dioxide (silica) as a constituent of living organisms is mainly restricted to diatoms and sponges, the ways in which this process is controlled by nature continue to inspire and fascinate. Both diatoms and sponges carry out biosilificiation using an organic matrix but they adopt very different strategies. Diatoms use small and heavily modified peptides called silaffins, where the most characteristic feature is a modulation of charge by attaching long chain polyamines (LCPAs) to lysine groups. Free LCPAs can also cooperate with silaffins. Sponges use the enzyme silicatein which is homologous to the cysteine protease cathepsin. Both classes of proteins form higher-order structures which act both as structural templates and mechanistic catalysts for the polycondensation reaction. In both cases, additional proteins are continuously being discovered which modulate the process further. This paper concentrates on the role of these proteins in the biosilification process as well as in various applications, highlighting areas where focus on specific protein properties may provide further insight. The field of biosilification is a crossroads of different disciplines, where insight into the energetics and mechanisms of molecular self-assembly combine with fundamental biology, complex multicomponent colloidal systems, and an impressive array of potential technological applications.

scholarly journals Cross-talk between individual phenol-soluble modulins in Staphylococcus aureus biofilm enables rapid and efficient amyloid formation

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Masihuz Zaman ◽  
Maria Andreasen
Keyword(s):  
Staphylococcus Aureus ◽  
Self Assembly ◽  
Biofilm Formation ◽  
Opportunistic Pathogen ◽  
Amyloid Formation ◽  
Secondary Nucleation ◽  
Primary Nucleation ◽  
Functional Amyloids ◽  
High Degree

The infective ability of the opportunistic pathogen Staphylococcus aureus, recognized as the most frequent cause of biofilm-associated infections, is associated with biofilm-mediated resistance to host immune response. Phenol-soluble modulins (PSM) comprise the structural scaffold of S. aureus biofilms through self-assembly into functional amyloids, but the role of individual PSMs during biofilm formation remains poorly understood and the molecular pathways of PSM self-assembly are yet to be identified. Here we demonstrate high degree of cooperation between individual PSMs during functional amyloid formation. PSMα3 initiates the aggregation, forming unstable aggregates capable of seeding other PSMs resulting in stable amyloid structures. Using chemical kinetics we dissect the molecular mechanism of aggregation of individual PSMs showing that PSMα1, PSMα3 and PSMβ1 display secondary nucleation whereas PSMβ2 aggregates through primary nucleation and elongation. Our findings suggest that various PSMs have evolved to ensure fast and efficient biofilm formation through cooperation between individual peptides.

scholarly journals Role of interface properties in organic solar cells: from substrate engineering to bulk-heterojunction interfacial morphology

2020 ◽  
Vol 4 (10) ◽  
pp. 2863-2880 ◽  
Author(s):  
Hong Zhang ◽  
Yanxun Li ◽  
Xuning Zhang ◽  
Yuan Zhang ◽  
Huiqiong Zhou
Keyword(s):  
Phase Separation ◽  
Organic Solar Cells ◽  
Self Assembly ◽  
Bulk Heterojunction ◽  
Film Deposition ◽  
Interface Properties ◽  
Substrate Engineering ◽  
Phase Separation Kinetics ◽  
Separation Kinetics

Surface properties control provides tools for tailoring the active layer self-assembly and phase separation kinetics, which plays an important role in the morphology by directing phase separation during film deposition, drying and annealing.

An insight into the role of riboflavin ligand in the self-assembly of poly(lactic-co-glycolic acid)-based nanoparticles – a molecular simulation and experimental approach

Soft Matter ◽  
2020 ◽  
Vol 16 (22) ◽  
pp. 5250-5260 ◽  
Author(s):  
Sima Rezvantalab ◽  
Mostafa Keshavarz Moraveji ◽  
Mohammad Khedri ◽  
Reza Maleki
Keyword(s):  
Molecular Simulation ◽  
Self Assembly ◽  
Targeted Delivery ◽  
Glycolic Acid ◽  
Experimental Approach ◽  
The Self ◽  
Insight Into

Nanoparticles (NPs) used for targeted delivery purposes are rapidly gaining importance in diagnostic and therapeutic fields.

Insight into the Role of Hydrogen Bonding in the Molecular Self-Assembly Process of Sulfamethazine Solvates

2017 ◽  
Vol 17 (12) ◽  
pp. 6151-6157 ◽  
Author(s):  
Xia Zhang ◽  
Ling Zhou ◽  
Chang Wang ◽  
Yang Li ◽  
Yanan Wu ◽  
...  
Keyword(s):  
Hydrogen Bonding ◽  
Self Assembly ◽  
Assembly Process ◽  
Insight Into

Hydrogen bonded supramolecular structures: a further insight into the diamine-diol recognition and self-assembly

2000 ◽  
Vol 78 (6) ◽  
pp. 723-731 ◽  
Author(s):  
Stefano Roelens ◽  
Paolo Dapporto ◽  
Paola Paoli
Keyword(s):  
Molecular Recognition ◽  
Gas Phase ◽  
Self Assembly ◽  
Supramolecular Assembly ◽  
Supramolecular Structures ◽  
Unique Role ◽  
X Ray ◽  
Molecular Code ◽  
Insight Into

A new H-bonded supramolecular assembly of the diamine-diol family has been obtained from (1R,2R)-1,2-diaminocyclohexane (DAC) and (S)-1-phenyl-1,2-ethanediol (PED). The structure was characterized by single-crystal X-ray analysis and showed the typical architecture of DAC based assemblies, consisting of a three-stranded helicate coiling around a H-bonded core, with a predictable helicity sense determined by the configuration of DAC. The new assembly, while reconfirming the unique role of DAC as a powerful assembler of supramolecular structures, demonstrated that the C2 symmetry of diol partners employed so far is not essential for assembling helicates, although chirality is. In the case of the adduct between (1R,2R)-1,2-diaminocyclohexane and (2R,3R)-2,3-butanediol, molecular recognition and self-assembly have been shown to take place even in the absence of solvent, in the gas phase, where long crystals were formed by spontaneous organized aggregation of diamine-diol units. A thorough analysis of the results from the present and previous investigations has lead to a deeper understanding of the key features of the diamine-diol molecular code and of the requirements for recognition and assembly.Key words: supramolecular, hydrogen bonding, molecular recognition, self-assembly, diamines, diols.

scholarly journals Amyloidogenicity and cytotoxicity of des-Lys-1 human amylin provides insight into amylin self-assembly and highlights the difficulties of defining amyloidogenicity

2019 ◽  
Vol 32 (2) ◽  
pp. 87-93 ◽  
Author(s):  
Kyung-Hoon Lee ◽  
Alexander Zhyvoloup ◽  
Daniel Raleigh
Keyword(s):  
Self Assembly ◽  
Amyloid Formation ◽  
Wild Type ◽  
Islet Amyloid ◽  
High Charge Density ◽  
Human Amylin ◽  
Phosphate Buffered Saline

Abstract The polypeptide amylin is responsible for islet amyloid in type 2 diabetes, a process which contributes to β-cell death in the disease. The role of the N-terminal region of amylin in amyloid formation is relatively unexplored, although removal of the disulfide bridged loop between Cys-2 and Cys-7 accelerates amyloid formation. We examine the des Lys-1 variant of human amylin (h-amylin), a variant which is likely produced in vivo. Lys-1 is a region of high charge density in the h-amylin amyloid fiber. The des Lys-1 polypeptide forms amyloid on the same time scale as wild-type amylin in phosphate buffered saline, but does so more rapidly in Tris. The des Lys-1 variant is somewhat less toxic to cultured INS cells than wild type. The implications for the in vitro mechanism of amyloid formation and for comparative analysis of amyloidogenicity are discussed.

scholarly journals Further insight into the role of metals in amyloid formation by IAPP1-37 and ProIAPP1-48

2015 ◽  
Vol 4 (1) ◽  
pp. 4 ◽  
Author(s):  
Matthew Mold ◽  
Chayanit Bunrat ◽  
Priya Goswami ◽  
Adam Roberts ◽  
Charlotte Roberts ◽  
...  
Keyword(s):  
Amyloid Formation ◽  
Insight Into

scholarly journals An Assembly-incompetent Mutant Establishes a Requirement for Dynamin Self-assembly in Clathrin-mediated Endocytosis In Vivo

2004 ◽  
Vol 15 (5) ◽  
pp. 2243-2252 ◽  
Author(s):  
Byeong Doo Song ◽  
Defne Yarar ◽  
Sandra L. Schmid
Keyword(s):  
Self Assembly ◽  
Point Mutations ◽  
Dominant Negative ◽  
Dominant Negative Mutant ◽  
Gtpase Activity ◽  
Insight Into ◽  
Assay Conditions ◽  
In Cells

Dynamin GTPase activity is required for its biological function in clathrin-mediated endocytosis; however, the role of self-assembly has not been unambiguously established. Indeed, overexpression of a dynamin mutant, Dyn1-K694A, with impaired ability to self-assemble has been shown to stimulate endocytosis in HeLa cells (Sever et al., Nature 1999, 398, 481). To identify new, assembly-incompetent mutants of dynamin 1, we made point mutations in the GTPase effector/assembly domain (GED) and tested for their effects on self-assembly and clathrin-mediated endocytosis. Mutation of three residues, I690, K694, and I697, suggests that interactions with an amphipathic helix in GED are required for self-assembly. In particular, Dyn1-I690K failed to exhibit detectable assembly-stimulated GTPase activity under all assay conditions. Overexpression of this assembly-incompetent mutant inhibited transferrin endocytosis as potently as the GTPase-defective dominant-negative mutant, Dyn1-K44A. However, worm-like endocytic intermediates accumulated in cells expressing Dyn1-I690K that were structurally distinct from long tubules that accumulated in cells expressing Dyn1-K44A. Together these results provide new structural insight into the role of GED in self-assembly and assembly-stimulated GTPase activity and establish that dynamin self-assembly is essential for clathrin-mediated endocytosis.

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