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Kancharla S, Dong D, Bedrov D, Tsianou M, Alexandridis P. Structure and Interactions in Perfluorooctanoate Micellar Solutions Revealed by Small-Angle Neutron Scattering and Molecular Dynamics Simulations Studies: Effect of Urea. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:5339-5347. [PMID: 33885307 DOI: 10.1021/acs.langmuir.1c00433] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The self-assembly of surfactants in aqueous solution can be modulated by the presence of additives including urea, which is a well-known protein denaturant and also present in physiological fluids and agricultural runoff. This study addresses the effects of urea on the structure of micelles formed in water by the fluorinated surfactant perfluoro-n-octanoic acid ammonium salt (PFOA). Analysis of small-angle neutron scattering (SANS) experiments and atomistic molecular dynamics (MD) simulations provide consensus strong evidence for the direct mechanism of urea action on micellization: urea helps solvate the hydrophobic micelle core by localizing at the surface of the core in the place of some water molecules. Consequently, urea decreases electrostatic interactions at the micelle shell, changes the micelle shape from prolate ellipsoid to sphere, and decreases the number of surfactant molecules associating in a micelle. These findings inform the interactions and behavior of surface active per- and polyfluoroalkyl substances (PFAS) released in the aqueous environment and biota.
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Affiliation(s)
- Samhitha Kancharla
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, New York 14260-4200, United States
| | - Dengpan Dong
- Department of Materials Science and Engineering, University of Utah, 122 S. Central Campus Drive, Room 304, Salt Lake City, Utah 84112, United States
| | - Dmitry Bedrov
- Department of Materials Science and Engineering, University of Utah, 122 S. Central Campus Drive, Room 304, Salt Lake City, Utah 84112, United States
| | - Marina Tsianou
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, New York 14260-4200, United States
| | - Paschalis Alexandridis
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, New York 14260-4200, United States
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Gawali SL, Zhang M, Kumar S, Ray D, Basu M, Aswal VK, Danino D, Hassan PA. Discerning the Structure Factor of Charged Micelles in Water and Supercooled Solvent by Contrast Variation X-ray Scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:9867-9877. [PMID: 31271288 DOI: 10.1021/acs.langmuir.9b00912] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Sodium dodecyl sulfate (SDS) is a well-known anionic surfactant that forms micelles in various solvents including supercooled sugar-urea melt. Here, we explore the application of contrast variation small-angle X-ray scattering (SAXS) in discerning the structure and interactions of SDS micelles in aqueous solution and in a room-temperature supercooled solvent. The SAXS patterns can be analyzed in terms of a core-shell ellipsoid model. For aqueous SDS micelles, at low volume fractions, the features due to intermicellar interaction, S(q), in the SAXS pattern are poorly resolved because of the prominent contribution from shell scattering. Increasing the electron density of the solvent by the addition of the urea or fructose-urea mixture (at a weight ratio of 6:4) permits the systematic variation of shell scattering without influencing the structure drastically. For a 10% solution of SDS in water, the contribution from the shell can be completely masked by the addition of 40% urea or fructose-urea mixture. The fructose-urea mixture is a preferred additive as it can vary the scattering length density over a wide range and serves as a matrix to form supercooled micelles. The structural parameters of micelles in supercooled fructose-urea melt are obtained from contrast variation SAXS, small-angle neutron scattering, and high-resolution transmission electron microscopy.
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Affiliation(s)
- Santosh L Gawali
- Homi Bhabha National Institute , Training School Complex , Anushaktinagar, Mumbai 400 094 , India
| | - Mingming Zhang
- Faculty of Biotechnology and Food Engineering , Technion-Israel Institute of Technology , Haifa 32000 , Israel
| | | | | | | | - Vinod K Aswal
- Homi Bhabha National Institute , Training School Complex , Anushaktinagar, Mumbai 400 094 , India
| | - Dganit Danino
- Faculty of Biotechnology and Food Engineering , Technion-Israel Institute of Technology , Haifa 32000 , Israel
| | - Puthusserickal A Hassan
- Homi Bhabha National Institute , Training School Complex , Anushaktinagar, Mumbai 400 094 , India
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Li X, Zhong K, Yin Z, Hu J, Wang W, Li L, Zhang H, Zheng X, Wang P, Zhang Z. The seven transmembrane domain protein MoRgs7 functions in surface perception and undergoes coronin MoCrn1-dependent endocytosis in complex with Gα subunit MoMagA to promote cAMP signaling and appressorium formation in Magnaporthe oryzae. PLoS Pathog 2019; 15:e1007382. [PMID: 30802274 PMCID: PMC6405168 DOI: 10.1371/journal.ppat.1007382] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 03/07/2019] [Accepted: 01/29/2019] [Indexed: 01/09/2023] Open
Abstract
Regulator of G-protein signaling (RGS) proteins primarily function as GTPase-accelerating proteins (GAPs) to promote GTP hydrolysis of Gα subunits, thereby regulating G-protein mediated signal transduction. RGS proteins could also contain additional domains such as GoLoco to inhibit GDP dissociation. The rice blast fungus Magnaporthe oryzae encodes eight RGS and RGS-like proteins (MoRgs1 to MoRgs8) that have shared and distinct functions in growth, appressorium formation and pathogenicity. Interestingly, MoRgs7 and MoRgs8 contain a C-terminal seven-transmembrane domain (7-TM) motif typical of G-protein coupled receptor (GPCR) proteins, in addition to the conserved RGS domain. We found that MoRgs7, but not MoRgs8, couples with Gα MoMagA to undergo endocytic transport from the plasma membrane to the endosome upon sensing of surface hydrophobicity. We also found that MoRgs7 can interact with hydrophobic surfaces via a hydrophobic interaction, leading to the perception of environmental hydrophobiccues. Moreover, we found that MoRgs7-MoMagA endocytosis is regulated by actin patch-associated protein MoCrn1, linking it to cAMP signaling. Our studies provided evidence suggesting that MoRgs7 could also function in a GPCR-like manner to sense environmental signals and it, together with additional proteins of diverse functions, promotes cAMP signaling required for developmental processes underlying appressorium function and pathogenicity.
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Affiliation(s)
- Xiao Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Kaili Zhong
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Ziyi Yin
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Jiexiong Hu
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Wenhao Wang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Lianwei Li
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Haifeng Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Xiaobo Zheng
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
| | - Ping Wang
- Departments of Pediatrics, and Microbiology, Immunology, and Parasitology, Louisiana State University Health Sciences Center, New Orleans, Louisiana, United States of America
| | - Zhengguang Zhang
- Department of Plant Pathology, College of Plant Protection, Nanjing Agricultural University, and Key Laboratory of Integrated Management of Crop Diseases and Pests, Ministry of Education, Nanjing, China
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