scholarly journals Downhill, Ultrafast and Fast Folding Proteins Revised

2020 ◽  
Vol 21 (20) ◽  
pp. 7632
Author(s):  
Mateusz Banach ◽  
Katarzyna Stapor ◽  
Leszek Konieczny ◽  
Piotr Fabian ◽  
Irena Roterman
Keyword(s):  
Amino Acids ◽  
Protein Folding ◽  
Gaussian Function ◽  
Water Environment ◽  
Mutual Arrangement ◽  
Hydrophobic Core ◽  
Spherical Micelle ◽  
Native Form ◽  
Hydrophobic Residues ◽  
Folding Process

Research on the protein folding problem differentiates the protein folding process with respect to the duration of this process. The current structure encoded in sequence dogma seems to be clearly justified, especially in the case of proteins referred to as fast-folding, ultra-fast-folding or downhill. In the present work, an attempt to determine the characteristics of this group of proteins using fuzzy oil drop model is undertaken. According to the fuzzy oil drop model, a protein is a specific micelle composed of bi-polar molecules such as amino acids. Protein folding is regarded as a spherical micelle formation process. The presence of covalent peptide bonds between amino acids eliminates the possibility of free mutual arrangement of neighbors. An example would be the construction of co-micelles composed of more than one type of bipolar molecules. In the case of fast folding proteins, the amino acid sequence represents the optimal bipolarity system to generate a spherical micelle. In order to achieve the native form, it is enough to have an external force field provided by the water environment which directs the folding process towards the generation of a centric hydrophobic core. The influence of the external field can be expressed using the 3D Gaussian function which is a mathematical model of the folding process orientation towards the concentration of hydrophobic residues in the center with polar residues exposed on the surface. The set of proteins under study reveals a hydrophobicity distribution compatible with a 3D Gaussian distribution, taken as representing an idealized micelle-like distribution. The structure of the present hydrophobic core is also discussed in relation to the distribution of hydrophobic residues in a partially unfolded form.

scholarly journals Different Synergy in Amyloids and Biologically Active Forms of Proteins

2019 ◽  
Vol 20 (18) ◽  
pp. 4436 ◽  
Author(s):  
Piotr Fabian ◽  
Katarzyna Stapor ◽  
Mateusz Banach ◽  
Magdalena Ptak-Kaczor ◽  
Leszek Konieczny ◽  
...  
Keyword(s):  
Amino Acids ◽  
Comparative Analysis ◽  
Protein Structure ◽  
Tertiary Structure ◽  
Protein Structures ◽  
Water Environment ◽  
Biologically Active ◽  
Radius Of Curvature ◽  
Hydrophobic Core ◽  
Structural Form

Protein structure is the result of the high synergy of all amino acids present in the protein. This synergy is the result of an overall strategy for adapting a specific protein structure. It is a compromise between two trends: The optimization of non-binding interactions and the directing of the folding process by an external force field, whose source is the water environment. The geometric parameters of the structural form of the polypeptide chain in the form of a local radius of curvature that is dependent on the orientation of adjacent peptide bond planes (result of the respective Phi and Psi rotation) allow for a comparative analysis of protein structures. Certain levels of their geometry are the criteria for comparison. In particular, they can be used to assess the differences between the structural form of biologically active proteins and their amyloid forms. On the other hand, the application of the fuzzy oil drop model allows the assessment of the role of amino acids in the construction of tertiary structure through their participation in the construction of a hydrophobic core. The combination of these two models—the geometric structure of the backbone and the determining of the participation in the construction of the tertiary structure that is applied for the comparative analysis of biologically active and amyloid forms—is presented.

scholarly journals Structure of the Hydrophobic Core Determines the 3D Protein Structure—Verification by Single Mutation Proteins

Biomolecules ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 767 ◽  
Author(s):  
Mateusz Banach ◽  
Piotr Fabian ◽  
Katarzyna Stapor ◽  
Leszek Konieczny ◽  
and Irena Roterman
Keyword(s):  
Tertiary Structure ◽  
Polypeptide Chain ◽  
De Novo ◽  
Water Environment ◽  
Single Mutation ◽  
Hydrophobic Core ◽  
3D Protein Structure ◽  
Folding Process ◽  
External Force Field ◽  
A Chain

Four de novo proteins differing in single mutation positions, with a chain length of 56 amino acids, represent diverse 3D structures: monomeric 3α and 4β + α folds. The reason for this diversity is seen in the different structure of the hydrophobic core as a result of synergy leading to the generation of a system in which the polypeptide chain as a whole participates. On the basis of the fuzzy oil drop model, where the structure of the hydrophobic core is expressed by means of the hydrophobic distribution function in the form of a 3D Gaussian distribution, it has been shown that the composition of the hydrophobic core in these two structural forms is different. In addition, the use of a model to determine the structure of the early intermediate in the folding process allows to indicate differences in the polypeptide chain geometry, which, combined with the construction of a common hydrophobic nucleus as an effect of specific synergy, may indicate the reason for the diversity of the folding process of the polypeptide chain. The results indicate the need to take into account the presence of an external force field originating from the water environment and that its active impact on the formation of a hydrophobic core whose participation in the stabilization of the tertiary structure is fundamental.

Pathway and stability of protein folding

1991 ◽  
Vol 332 (1263) ◽  
pp. 171-176 ◽  
Keyword(s):  
Protein Folding ◽  
Protein Engineering ◽  
Hydrogen Exchange ◽  
Hydrophobic Core ◽  
Wild Type ◽  
Kinetic Measurements ◽  
Mutant Proteins ◽  
Folding Process ◽  
Β Sheet

We describe an experimental approach to the problem of protein folding and stability which measures interaction energies and maps structures of intermediates and transition states during the folding pathway. The strategy is based on two steps. First, protein engineering is used to remove interactions that stabilize defined positions in barnase, the RNAse from Bacillus amyloliquefaciens . The consequent changes in stability are measured from the changes in free energy of unfolding of the protien. Second, each mutation is used as a probe of the structure around the wild-type side chain during the folding process. Kinetic measurements are made on the folding and unfolding of wild-type and mutant proteins. The kinetic and thermodynamic data are combined and analysed to show the role of individual side chains in the stabilization of the folded, transition and intermediate states of the protein. The protein engineering experiments are corroborated by nuclear magnetic resonance studies of hydrogen exchange during the folding process. Folding is a multiphasic process in which α-helices and β-sheet are formed relatively early. Formation of the hydrophobic core by docking helix and sheet is (partly) rate determining. The final steps involve the forming of loops and the capping of the N-termini of helices.

scholarly journals Atomic insights into the effects of pathological mutants through the disruption of hydrophobic core in the prion protein

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Juhwan Lee ◽  
Iksoo Chang ◽  
Wookyung Yu
Keyword(s):  
Amino Acids ◽  
Protein Folding ◽  
Prion Protein ◽  
Hydrophobic Interactions ◽  
Energy Difference ◽  
Hydrophobic Core ◽  
Free Energy Difference ◽  
The Stability ◽  
Simulation Time ◽  
Folding Free Energy

AbstractDestabilization of prion protein induces a conformational change from normal prion protein (PrPC) to abnormal prion protein (PrPSC). Hydrophobic interaction is the main driving force for protein folding, and critically affects the stability and solvability. To examine the importance of the hydrophobic core in the PrP, we chose six amino acids (V176, V180, T183, V210, I215, and Y218) that make up the hydrophobic core at the middle of the H2-H3 bundle. A few pathological mutants of these amino acids have been reported, such as V176G, V180I, T183A, V210I, I215V, and Y218N. We focused on how these pathologic mutations affect the hydrophobic core and thermostability of PrP. For this, we ran a temperature-based replica-exchange molecular dynamics (T-REMD) simulation, with a cumulative simulation time of 28 μs, for extensive ensemble sampling. From the T-REMD ensemble, we calculated the protein folding free energy difference between wild-type and mutant PrP using the thermodynamic integration (TI) method. Our results showed that pathological mutants V176G, T183A, I215V, and Y218N decrease the PrP stability. At the atomic level, we examined the change in pair-wise hydrophobic interactions from valine-valine to valine-isoleucine (and vice versa), which is induced by mutation V180I, V210I (I215V) at the 180th–210th (176th–215th) pair. Finally, we investigated the importance of the π-stacking between Y218 and F175.

scholarly journals Divergence Entropy-Based Evaluation of Hydrophobic Core in Aggressive and Resistant Forms of Transthyretin

Entropy ◽  
2021 ◽  
Vol 23 (4) ◽  
pp. 458
Author(s):  
Mateusz Banach ◽  
Katarzyna Stapor ◽  
Piotr Fabian ◽  
Leszek Konieczny ◽  
Irena Roterman
Keyword(s):  
Tertiary Structure ◽  
Early Stage ◽  
Intermediate Stage ◽  
Transformation Process ◽  
Hydrophobic Core ◽  
Spherical Micelle ◽  
Globular Structure ◽  
Folding Process ◽  
Decisive Importance ◽  
The Status

The two forms of transthyretin differing slightly in the tertiary structure, despite the presence of five mutations, show radically different properties in terms of susceptibility to the amyloid transformation process. These two forms of transthyretin are the object of analysis. The search for the sources of these differences was carried out by means of a comparative analysis of the structure of these molecules in their native and early intermediate stage forms in the folding process. The criterion for assessing the degree of similarity and differences is the status of the hydrophobic core. The comparison of the level of arrangement of the hydrophobic core and its initial stages is possible thanks to the application of divergence entropy for the early intermediate stage and for the final forms. It was shown that the minimal differences observed in the structure of the hydrophobic core of the forms available in PDB, turned out to be significantly different in the early stage (ES) structure in folding process. The determined values of divergence entropy for both ES forms indicate the presence of the seed of hydrophobic core only in the form resistant to amyloid transformation. In the form of aggressively undergoing amyloid transformation, the structure lacking such a seed is revealed, being a stretched one with a high content of β-type structure. In the discussed case, the active presence of water in the structural transformation of proteins expressed in the fuzzy oil drop model (FOD) is of decisive importance for the generation of the final protein structure. It has been shown that the resistant form tends to generate a centric hydrophobic core with the possibility of creating a globular structure, i.e. a spherical micelle-like form. The aggressively transforming form reveals in the structure of its early intermediate, a tendency to form the ribbon-like micelle as observed in amyloid.

scholarly journals Time-dependent communication between multiple amino acids during protein folding

2021 ◽  
Vol 12 (16) ◽  
pp. 5944-5951
Author(s):  
Song-Ho Chong ◽  
Sihyun Ham
Keyword(s):  
Amino Acids ◽  
Protein Folding ◽  
Transition State ◽  
Time Dependent ◽  
Transition Path ◽  
Contact Formation ◽  
Molecular Origin

Cooperativity in contact formation among multiple amino acids starts to develop upon entering the folding transition path and attains a maximum at the folding transition state, providing the molecular origin of the two-state folding behavior.

Models of cooperativity in protein folding

1995 ◽  
Vol 348 (1323) ◽  
pp. 61-70 ◽  
Keyword(s):  
Protein Folding ◽  
Molten Globule ◽  
Core Collapse ◽  
Hydrophobic Core ◽  
Model Studies ◽  
Helix Formation ◽  
Collapse Model ◽  
Folding Pathways ◽  
State Behaviour ◽  
Denatured States

What is the basis for the two-state cooperativity of protein folding? Since the 1950s, three main models have been put forward. 1. In ‘helix-coil’ theory, cooperativity is due to local interactions among near neighbours in the sequence. Helix-coil cooperativity is probably not the principal basis for the folding of globular proteins because it is not two-state, the forces are weak, it does not account for sheet proteins, and there is no evidence that helix formation precedes the formation of a hydrophobic core in the folding pathways. 2. In the ‘sidechain packing’ model, cooperativity is attributed to the jigsaw-puzzle-like complementary fits of sidechains. This too is probably not the basis of folding cooperativity because exact models and experiments on homopolymers with sidechains give no evidence that sidechain freezing is two-state, sidechain complementarities in proteins are only weak trends, and the molten globule model predicted by this model is far more native-like than experiments indicate. 3. In the ‘hydrophobic core collapse’ model, cooperativity is due to the assembly of non-polar residues into a good core. Exact model studies show that this model gives two-state behaviour for some sequences of hydrophobic and polar monomers. It is based on strong forces. There is considerable experimental evidence for the kinetics this model predicts: the development of hydrophobic clusters and cores is concurrent with secondary structure formation. It predicts compact denatured states with sizes and degrees of disorder that are in reasonable agreement with experiments.

Sign in / Sign up

Export Citation Format

Share Document