Interconnection of Salt-induced Hydrophobic Compaction and Secondary Structure Formation Depends on Solution Conditions

Haldar, Shubhasis; Chattopadhyay, Krishnananda

doi:10.1074/jbc.m111.315648

Cited by 26 publications

(55 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This value is much larger than that for completely unfolded protein and it matches closely with the size of BSA in the aggregated condition. [63,64] The conformational relaxation time t R increases from 35 ms in the native state to 50 ms in the completely unfolded state when the DMSO-induced transition occurs. Thus, we suggest that when the protein is completely unfolded, an enhanced protein-protein interaction at high concentration of DMSO results in its aggregation.…”

Section: Discussionmentioning

confidence: 99%

Structural Transformation of Bovine Serum Albumin Induced by Dimethyl Sulfoxide and Probed by Fluorescence Correlation Spectroscopy and Additional Methods

2013

View full text Add to dashboard Cite

Determining the structure of a protein and its transformation under different conditions is key to understanding its activity. The structural stability and activity of proteins in aqueous-organic solvent mixtures, which is an intriguing topic of research in biochemistry, is dependent on the nature of the protein and the properties of the medium. Herein, the effect of a commonly used cosolvent, dimethyl sulfoxide (DMSO), on the structure and conformational dynamics of bovine serum albumin (BSA) protein is studied by fluorescence correlation spectroscopy (FCS) measurements on fluorescein isothiocyanate (FITC)-labeled BSA. The FCS study reveals a change of the hydrodynamic radius of BSA from 3.7 nm in the native state to 7.0 nm in the presence of 40% DMSO, which suggests complete unfolding of the protein under these conditions. Fluorescence self-quenching of FITC has been exploited to understand the conformational dynamics of BSA. The time constant of the conformational dynamics of BSA is found to change from 35 μs in its native state to 50 μs as the protein unfolds with increasing DMSO concentration. The FCS results are corroborated by the near-UV circular dichroism spectra of the protein, which suggest a loss of its tertiary structure with increasing concentration of DMSO. The intrinsic fluorescence of BSA and the fluorescence response of 1-anilinonaphthalene-8-sulfonic acid, used as a probe molecule, provide information that is consistent with the FCS measurements, except that aggregation of BSA is observed in the presence of 40% DMSO in the ensemble measurements.

show abstract

Section: Discussionmentioning

confidence: 99%

Structural Transformation of Bovine Serum Albumin Induced by Dimethyl Sulfoxide and Probed by Fluorescence Correlation Spectroscopy and Additional Methods

2013

View full text Add to dashboard Cite

show abstract

“…It has recently been shown that the hydrophobic clustering and the generation of secondary structure may occur in subsequent steps or in concert depending on solution conditions. 27 We have also found that hydrophobic mutation at the hydrophobic core can speed up early contact formation, resulting in misfolding; while similar increase in hydrophobicity elsewhere in the same protein did not seem to have any significant effect. 23 At the early stage of folding, local hydrophobic contact formation is expected to predominate over the long distant interactions, which is presumably the reason for the observed helical structure in the intermediate state.…”

Section: Resultsmentioning

confidence: 60%

“…Although there exist many controversies regarding the early events of protein folding, it is generally believed that different processes may compete, resulting in significant heterogeneity. It has recently been shown that the hydrophobic clustering and the generation of secondary structure may occur in subsequent steps or in concert depending on solution conditions . We have also found that hydrophobic mutation at the hydrophobic core can speed up early contact formation, resulting in misfolding; while similar increase in hydrophobicity elsewhere in the same protein did not seem to have any significant effect .…”

Section: Resultsmentioning

confidence: 61%

“…Goto et al observed the accumulation of early helices in the case of a predominantly b-sheet protein b-lactoglobulin. 5 Earlier it has been shown that the formation of hydrophobic contacts and the generation of local secondary structure depend on several factors including the nature of solvent 27 and mutation at the area of hydrophobic clustering. 23 To get more insights into the conformation changes at different pH, we have studied the binding of 1-anilino-8-naphthalene-sulfonate (ANS) to MPT63.…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

The presence of non‐native helical structure in the unfolding of a beta‐sheet protein MPT63

Kundu

Chattopadhyay

2017

Protein Science

Self Cite

View full text Add to dashboard Cite

MPT63, a major secreted protein from Mycobacterium tuberculosis, has been shown to have immunogenic properties and has been implicated in virulence. MPT63 is a b-sandwich protein containing 11 b strands and a very short stretch of 3 10 helix. The detailed experimental and computational study reported here investigates the equilibrium unfolding transition of MPT63. It is shown that in spite of being a complete b-sheet protein, MPT63 has a strong propensity toward helix structures in its early intermediates. Far UV-CD and FTIR spectra clearly suggest that the low-pH intermediate of MTP63 has enhanced helical content, while fluorescence correlation spectroscopy suggests a significant contraction. Molecular dynamics simulation complements the experimental results indicating that the unfolded state of MPT63 traverses through intermediate forms with increased helical characteristics. It is found that this early intermediate contains exposed hydrophobic surface, and is aggregation prone. Although MPT63 is a complete b-sheet protein in its native form, the present findings suggest that the secondary structure preferences of the local interactions in early folding pathway may not always follow the native conformation. Furthermore, the Gly25Ala mutant supports the proposed hypothesis by increasing the non-native helical propensity of the protein structure.

show abstract

“…In contrast, in the presence of urea, a compaction of the protein radius occurs gradually over an extended range of salt concentration following homopolymer formalism. The salt induced compaction and the formation of secondary structure take place simultaneously in the presence of urea [100].…”

Section: Determinants Of Protein Foldsmentioning

confidence: 99%

Protein Folding and Misfolding: A Perspective from Theory

TA¹

2015

J Glycomics Lipidomics

View full text Add to dashboard Cite

IntroductionIn appropriate physiological milieu proteins spontaneously fold into their functional three-dimensional structures. The amino acid sequences of functional proteins contain all the information necessary to specify the folds [1,2]. The manner in which a newly synthesized chain of amino acids transforms itself into a perfectly folded protein depends both on the intrinsic properties of the amino-acid sequence and on multiple contributing influences from the crowded cellular milieu. The wide variety of highly specific structures that result from protein folding and that bring key functional groups into close proximity has enabled living systems to develop astonishing diversity and selectivity in their underlying chemical processes. In addition to generating biological activity, we now know that folding is coupled to many other biological processes, including the trafficking of molecules to specific cellular locations and the regulation of cellular growth and differentiation [3,4].Add to it, correctly folded proteins have long-term stability in crowded biological environments and are able to interact selectively with their natural partners. It is therefore not surprising that the failure of proteins to fold correctly is the origin of a wide variety of pathological conditions [5]. Some concepts, such as energy landscape, Gibbs energy landscape and co-operativity frequently used in the theory of protein folding are examined exactly in one-dimensional systems. It is shown that much of the confusion that exists regarding these, and other concepts arise from the misinterpretation of Anfinsen's thermodynamic hypothesis [6].Moreover, proteins are involved in virtually every biological process and their functions range from catalysis of chemical reactions to maintenance of the electrochemical potential across cell membranes. The molecular conformation of proteins is sensitive to the nature of the aqueous environment [7]. They are synthesized on ribosomes as linear chains of amino acids in a specific order from information encoded within the cellular DNA. To function, it is necessary for these chains to fold into the unique native three dimensional structures that are characteristic for each protein (Figure 1). This involves a complex molecular recognition phenomenon that depends on the cooperative action of many relatively weak non-bonding interactions. As the number of possible conformations for a polypeptide chain is astronomically large, a systematic search for the native (lowest energy) structure would require an almost infinite length of time. Recently, significant progress has been made towards solving this paradox and understanding the mechanism of folding. This has come about through advances in experimental strategies for following the folding reactions of proteins in the laboratory with biophysical techniques, and through progress in theoretical approaches that simulate the folding process with simplified models [8,9].Protein folding is a problem of great importance in both life sciences and biotechnolog...

show abstract

Interconnection of Salt-induced Hydrophobic Compaction and Secondary Structure Formation Depends on Solution Conditions

Cited by 26 publications

References 54 publications

Structural Transformation of Bovine Serum Albumin Induced by Dimethyl Sulfoxide and Probed by Fluorescence Correlation Spectroscopy and Additional Methods

Structural Transformation of Bovine Serum Albumin Induced by Dimethyl Sulfoxide and Probed by Fluorescence Correlation Spectroscopy and Additional Methods

The presence of non‐native helical structure in the unfolding of a beta‐sheet protein MPT63

Protein Folding and Misfolding: A Perspective from Theory

Contact Info

Product

Resources

About