Measurement of Thermodynamic Parameters for Hydrophobic Mismatch 2:  Intermembrane Transfer of a Transmembrane Helix†

Biochemistry ◽  
2006 ◽  
Vol 45 (10) ◽  
pp. 3379-3385 ◽  
Author(s):  
Yoshiaki Yano ◽  
Mai Ogura ◽  
Katsumi Matsuzaki
Keyword(s):  
Thermodynamic Parameters ◽  
Transmembrane Helix ◽  
Hydrophobic Mismatch

scholarly journals TatA and TatB generate a hydrophobic mismatch that is important for function and assembly of the Tat translocon in Escherichia coli

2021 ◽  
Author(s):  
Denise Mehner-Breitfeld ◽  
Michael T. Ringel ◽  
Daniel Alexander Tichy ◽  
Laura J. Endter ◽  
Kai Steffen Stroh ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Transmembrane Helix ◽  
Length Variation ◽  
Hydrophobic Mismatch ◽  
Hydrophobic Residues ◽  
Transmission Electron ◽  
Absolute Requirement ◽  
Bacterial Model ◽  
Folded Proteins ◽  
Dynamics Simulations

The Tat system translocates folded proteins across energy-transducing prokaryotic membranes. In the bacterial model system Escherichia coli, the three components TatA, TatB, and TatC assemble to functional translocons. TatA and TatB both possess an N-terminal transmembrane helix (TMH) that is followed by an amphipathic helix (APH). The TMHs of TatA and TatB generate a hydrophobic mismatch with only 12 consecutive hydrophobic residues that span the membrane. We shortened or extended this stretch of hydrophobic residues in either TatA, TatB, or both, and analyzed effects on transport functionality and translocon assembly. The wild type length functioned best but was not an absolute requirement, as some variation was tolerated. Length-variation in TatB clearly destabilized TatBC-containing complexes, indicating that the 12-residues-length is crucial for Tat component interactions and translocon assembly. Metal tagging transmission electron microscopy revealed the dimensions of TatA assemblies, which prompted molecular dynamics simulations. These showed that interacting TMHs of larger TatA assemblies can thin the membrane together with laterally aligned tilted APHs that generate a deep V-shaped groove. The conserved hydrophobic mismatch may thus be important for membrane destabilization during Tat transport, and the exact length of 12 hydrophobic residues could be a compromise between functionality and proton leakage minimization.

scholarly journals The Role of Hydrophobic Mismatch on Transmembrane Helix Dimerization in Living Cells

2019 ◽  
Vol 116 (3) ◽  
pp. 90a
Author(s):  
Brayan Grau ◽  
Matti Javanainen ◽  
Maria Jesús García-Murria ◽  
Waldemar Kulig ◽  
Ilpo Vattulainen ◽  
...  
Keyword(s):  
Transmembrane Helix ◽  
Living Cells ◽  
Hydrophobic Mismatch

Models of Thermodynamic Properties of Prominences

1979 ◽  
Vol 44 ◽  
pp. 349-355
Author(s):  
R.W. Milkey
Keyword(s):  
Thermodynamic Properties ◽  
Mass Transport ◽  
Emission Spectrum ◽  
Thermodynamic Parameters ◽  
Working Group ◽  
Physical Processes ◽  
Theoretical Concepts ◽  
Group 3 ◽  
Observational Techniques

The focus of discussion in Working Group 3 was on the Thermodynamic Properties as determined spectroscopically, including the observational techniques and the theoretical modeling of physical processes responsible for the emission spectrum. Recent advances in observational techniques and theoretical concepts make this discussion particularly timely. It is wise to remember that the determination of thermodynamic parameters is not an end in itself and that these are interesting chiefly for what they can tell us about the energetics and mass transport in prominences.

Coaction of Electrostatic and Hydrophobic Interactions: Dynamic Constraints on Disordered TrkA Juxtamembrane Domain

2019 ◽  
Author(s):  
Zichen Wang ◽  
Huaxun Fan ◽  
Xiao Hu ◽  
John Khamo ◽  
Jiajie Diao ◽  
...  
Keyword(s):  
Single Molecule ◽  
Protein Function ◽  
Hydrophobic Interactions ◽  
Transmembrane Helix ◽  
Point Mutations ◽  
Salt Bridge ◽  
Receptor Activation ◽  
Membrane Dynamics ◽  
Juxtamembrane Domain ◽  
Joint Work

<p>The receptor tyrosine kinase family transmits signals into cell via a single transmembrane helix and a flexible juxtamembrane domain (JMD). Membrane dynamics makes it challenging to study the structural mechanism of receptor activation experimentally. In this study, we employ all-atom molecular dynamics with Highly Mobile Membrane-Mimetic to capture membrane interactions with the JMD of tropomyosin receptor kinase A (TrkA). We find that PIP<sub>2 </sub>lipids engage in lasting binding to multiple basic residues and compete with salt bridge within the peptide. We discover three residues insertion into the membrane, and perturb it through computationally designed point mutations. Single-molecule experiments indicate the contribution from hydrophobic insertion is comparable to electrostatic binding, and in-cell experiments show that enhanced TrkA-JMD insertion promotes receptor ubiquitination. Our joint work points to a scenario where basic and hydrophobic residues on disordered domains interact with lipid headgroups and tails, respectively, to restrain flexibility and potentially modulate protein function.</p>

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