Role of Aromatic Side Chains in the Folding and Thermodynamic Stability of Integral Membrane Proteins

2007 ◽  
Vol 129 (26) ◽  
pp. 8320-8327 ◽  
Author(s):  
Heedeok Hong ◽  
Sangho Park ◽  
Ricardo H. Flores Jiménez ◽  
Dennis Rinehart ◽  
Lukas K. Tamm
Keyword(s):  
Membrane Proteins ◽  
Thermodynamic Stability ◽  
Integral Membrane Proteins ◽  
Side Chains ◽  
Aromatic Side Chains

scholarly journals Lipid Transporters Beam Signals from Cell Membranes

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 562
Author(s):  
Miliça Ristovski ◽  
Danny Farhat ◽  
Shelly Ellaine M. Bancud ◽  
Jyh-Yeuan Lee
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayers ◽  
Lipid Composition ◽  
Structural Integrity ◽  
Current Knowledge ◽  
Integral Membrane Proteins ◽  
Cellular Membranes ◽  
Cytoplasmic Proteins ◽  
Lipid Transporters

Lipid composition in cellular membranes plays an important role in maintaining the structural integrity of cells and in regulating cellular signaling that controls functions of both membrane-anchored and cytoplasmic proteins. ATP-dependent ABC and P4-ATPase lipid transporters, two integral membrane proteins, are known to contribute to lipid translocation across the lipid bilayers on the cellular membranes. In this review, we will highlight current knowledge about the role of cholesterol and phospholipids of cellular membranes in regulating cell signaling and how lipid transporters participate this process.

scholarly journals Free Energy Landscape and Rate Estimation of the Aromatic Ring Flips in Basic Pancreatic Trypsin Inhibitor Using Metadynamics

2021 ◽  
Author(s):  
Pär Söderhjelm ◽  
Mandar Kulkarni
Keyword(s):  
Free Energy ◽  
Trypsin Inhibitor ◽  
Side Chain ◽  
Side Chains ◽  
Aromatic Residues ◽  
Basic Pancreatic Trypsin Inhibitor ◽  
Pancreatic Trypsin Inhibitor ◽  
Energy Surfaces ◽  
Aromatic Side Chains

Aromatic side-chains (phenylalanine and tyrosine) of a protein flip by 180° around the Cβ-Cγ axis (χ2 dihedral of side-chain) producing two symmetry-equivalent states. The ring-flip dynamics act as an NMR probe to understand local conformational fluctuations. Ring-flips are categorized as slow (ms onwards) or fast (ns to near ms) based on timescales accessible to NMR experiments. In this study, we investigated the ability of the infrequent metadynamics approach to discriminate between slow and fast ring-flips for eight individual aromatic side-chains (F4, Y10, Y21, F22, Y23, F33, Y35, F45) of basic pancreatic trypsin inhibitor (BPTI). Well-tempered metadynamics simulations were performed to observe ring-flipping free energy surfaces for all eight aromatic residues. The results indicate that χ2 as a standalone collective variable (CV) is not sufficient to classify fast and slow ring-flips. Most of the residues needed χ1 (N−Cχα) as a complementary CV, indicating the importance of librational motions in ring-flips. Multiple pathways and mechanisms were observed for residues F4, Y10, and F22. Recrossing events are observed for residues F22 and F33, indicating a possible role of friction effects in the ring-flipping. The results demonstrate the successful application of the metadynamics based approach to estimate ring-flip rates of aromatic residues in BPTI and identify certain limitations of the approach.

Role of membrane proteins in permeability barrier function: uroplakin ablation elevates urothelial permeability

2002 ◽  
Vol 283 (6) ◽  
pp. F1200-F1207 ◽  
Author(s):  
Ping Hu ◽  
Susan Meyers ◽  
Feng-Xia Liang ◽  
Fang-Ming Deng ◽  
Bechara Kachar ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Water Permeability ◽  
Barrier Function ◽  
Apical Membrane ◽  
Integral Membrane Proteins ◽  
Transepithelial Resistance ◽  
Permeability Barrier ◽  
Major Protein ◽  
Apical Membranes

Although water, small nonelectrolytes, and gases are freely permeable through most biological membranes, apical membranes of certain barrier epithelia exhibit extremely low permeabilities to these substances. The role of integral membrane proteins in this barrier function has been unclear. To study this problem, we have ablated the mouse gene encoding uroplakin III (UPIII), one of the major protein subunits in urothelial apical membranes, and measured the permeabilities of these membranes. Ablation of the UPIII gene greatly diminishes the amounts of uroplakins on the apical urothelial membrane (Hu P, Deng FM, Liang FX, Hu CM, Auerbach AB, Shapiro E, Wu XR, Kachar B, and Sun TT. J Cell Biol151: 961–972, 2000). Our results indicate that normal mouse urothelium exhibits high transepithelial resistance and low urea and water permeabilities. The UPIII-deficient urothelium exhibits a normal transepithelial resistance (normal 2,024 ± 122, knockout 2,322 ± 114 Ω · cm2; P > 0.5). However, the UPIII-deficient apical membrane has a significantly elevated water permeability (normal 0.91 ± 0.06, knockout 1.83 ± 0.14 cm/s × 10−5; P < 0.05). The urea permeability of the UPIII-deficient membrane also increased, although to a lesser extent (normal 2.22 ± 0.24, knockout 2.93 ± 0.31 cm/s × 10−6; P = 0.12). These results indicate that reduced targeting of uroplakins to the apical membrane does not significantly alter the tight junctional barrier but does double the water permeability. We provide the first demonstration that integral membrane proteins contribute to the apical membrane permeability barrier function of urothelium.

scholarly journals Role of Aromatic Side Chains in Amyloid β-Protein Aggregation

2012 ◽  
Vol 3 (12) ◽  
pp. 1008-1016 ◽  
Author(s):  
Risto Cukalevski ◽  
Barry Boland ◽  
Birgitta Frohm ◽  
Eva Thulin ◽  
Dominic Walsh ◽  
...  
Keyword(s):  
Protein Aggregation ◽  
Amyloid Β ◽  
Side Chains ◽  
Amyloid Β Protein ◽  
Β Protein ◽  
Aromatic Side Chains

scholarly journals Exploring the Role of Integral Membrane Proteins in ATP-Binding Cassette Transporters: Analysis of a Collection of MalG Insertion Mutants

1998 ◽  
Vol 180 (9) ◽  
pp. 2507-2514 ◽  
Author(s):  
Bryn D. Nelson ◽  
Beth Traxler
Keyword(s):  
Membrane Proteins ◽  
Cytoplasmic Membrane ◽  
Binding Protein ◽  
Maltose Binding Protein ◽  
Integral Membrane Proteins ◽  
Atp Binding ◽  
Mutant Proteins ◽  
Transport Complex ◽  
Atp Binding Cassette

ABSTRACT The maltose transport complex of Escherichia coli is a well-studied example of an ATP-binding cassette transporter. The complex, containing one copy each of the integral membrane proteins MalG and MalF and two copies of the peripheral cytoplasmic membrane protein MalK, interacts with the periplasmic maltose-binding protein to efficiently translocate maltose and maltodextrins across the bacterial cytoplasmic membrane. To investigate the role of MalG both in MalFGK2 assembly interactions and in subsequent transport interactions, we isolated and characterized 18 different MalG mutants, each containing a 31-residue insertion in the protein. Eight insertions mapping to distinct hydrophilic regions of MalG permitted either assembly or both assembly and transport interactions to occur. In particular, we isolated two insertions mapping to extracytoplasmic (periplasmic) regions of MalG which preserved both assembly and transport abilities, suggesting that these are permissive sites in the protein. Another periplasmic insertion seems to affect only transport-specific interactions between MalG and maltose-binding protein, defining a novel class of MalG mutants. Finally, four MalG mutant proteins, although stably expressed, are unable to assemble into the MalFGK2 complex. These mutants contain insertions in only two different hydrophilic regions of MalG, consistent with the notion that a restricted number of domains in this protein are critical complex assembly determinants. These MalG mutants will allow us to further explore the intermolecular interactions of this model transporter.

On the Role of Aromatic Side Chains in the Photoactivation of BLUF Domains†

Biochemistry ◽  
2007 ◽  
Vol 46 (25) ◽  
pp. 7405-7415 ◽  
Author(s):  
Magdalena Gauden ◽  
Jeffrey S. Grinstead ◽  
Wouter Laan ◽  
Ivo H. M. van Stokkum ◽  
Marcela Avila-Perez ◽  
...  
Keyword(s):  
Side Chains ◽  
Aromatic Side Chains

The role of aromatic side chains on the supramolecular hydrogelation of naphthalimide/dipeptide conjugates

2018 ◽  
Vol 42 (6) ◽  
pp. 4443-4449 ◽  
Author(s):  
Shu-Min Hsu ◽  
Rajan Deepan Chakravarthy ◽  
Hsun Cheng ◽  
Fang-Yi Wu ◽  
Tsung-Sheng Lai ◽  
...  
Keyword(s):  
Amino Acid ◽  
Side Chain ◽  
Side Chains ◽  
Amino Acid Side Chain ◽  
Aromatic Side Chains

This study demonstrates the influence of an amino-acid side chain of NI-dipeptides on supramolecular hydrogelation and biocompatibility.

The role of aromatic side-chains in amyloid growth and membrane interaction of the islet amyloid polypeptide fragment LANFLVH

2010 ◽  
Vol 40 (1) ◽  
pp. 1-12 ◽  
Author(s):  
Danilo Milardi ◽  
Michele F. M. Sciacca ◽  
Matteo Pappalardo ◽  
Domenico M. Grasso ◽  
Carmelo La Rosa
Keyword(s):  
Islet Amyloid Polypeptide ◽  
Side Chains ◽  
Islet Amyloid ◽  
Membrane Interaction ◽  
Aromatic Side Chains
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