Chaohua Lai

University of Science and Technology of China

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Changlin Tian

University of Science and Technology of China

Longhua Zhang

University of Science and Technology of China

Ying Xiong

Huizhou Central People's Hospital

Fangming Wu

University of Chinese Academy of Sciences

Juan Li

China University of Petroleum, East China

Yao He

Guangdong University of Technology

Haowen Liu

China Jiliang University

Jiuping Ding

Washington University in St. Louis

Changlin Tian

Hefei Institutes of Physical Science

Pan Shi

University College London

Cooperative Institutions

University of Science and Technology of China

Chinese Academy of Sciences

High Magnetic Field Laboratory

Hefei National Center for Physical Sciences at Nanoscale

Hefei University

Huazhong University of Science and Technology

Hefei Institutes of Physical Science

Zhengzhou University

University of Chinese Academy of Sciences

Kunming Institute of Zoology

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Integrin α1 Has a Long Helix, Extending from the Transmembrane Region to the Cytoplasmic Tail in Detergent Micelles

PLoS ONE (2013)

Chaohua Lai Xiaoxi Liu Changlin Tian Fangming Wu

Integrin proteins are very important adhesion receptors that mediate cell-cell and cell-extracellular matrix interactions. They play essential roles in cell signaling and the regulation of cellular shape, motility, and the cell cycle. Here, the transmembrane and cytoplasmic (TMC) domains of integrin α1 and β1 were over-expressed and purified in detergent micelles. The structure and backbone relaxations of α1-TMC in LDAO micelles were determined and analyzed using solution NMR. A long helix, extending from the transmembrane region to the cytoplasmic tail, was observed in α1-TMC. Structural comparisons of α1-TMC with reported αIIb-TMC domains indicated different conformations in the transmembrane regions and cytoplasmic tails. An NMR titration experiment indicated weak interactions between α1-TMC and β1-TMC through several α1-TMC residues located at its N-terminal juxta-transmembrane region and C-terminal extended helix region.

Helix (gastropod)

Cell membrane

10.1371/journal.pone.0062954

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Solution NMR of MPS-1 Reveals a Random Coil Cytosolic Domain Structure

PLoS ONE (2014)

Pan Li Pan Shi Chaohua Lai Juan Li Yuanyuan Zheng

Caenorhabditis elegans MPS1 is a single transmembrane helical auxiliary subunit that co-localizes with the voltage-gated potassium channel KVS1 in the nematode nervous system. MPS-1 shares high homology with KCNE (potassium voltage-gated channel subfamily E member) auxiliary subunits, and its cytosolic domain was reported to have a serine/threonine kinase activity that modulates KVS1 channel function via phosphorylation. In this study, NMR spectroscopy indicated that the full length and truncated MPS-1 cytosolic domain (134–256) in the presence or absence of n-dodecylphosphocholine detergent micelles adopted a highly flexible random coil secondary structure. In contrast, protein kinases usually adopt a stable folded conformation in order to implement substrate recognition and phosphoryl transfer. The highly flexible random coil secondary structure suggests that MPS-1 in the free state is unstructured but may require a substrate or binding partner to adopt stable structure required for serine/threonine kinase activity.

Random coil

Coiled coil

Subfamily

Protein kinase domain

10.1371/journal.pone.0111035

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The HAB1 PP2C is inhibited by ABA-dependent PYL10 interaction

Scientific Reports (2015)

Juan Li Chaowei Shi Demeng Sun Yao He Chaohua Lai

Abstract PYL10 is a monomeric abscisic acid (ABA) receptor that inhibits protein phosphatase 2C (PP2C) activity in Arabidopsis thaliana . Previous studies reported that the PP2C phosphatase inhibition by PYL10 was ABA-independent. Here, systematic PYL10 biochemical studies demonstrated that PYL10 activity was ABA-dependent and the previously reported studies was interfered by the presence of BSA in the commercial kit. To investigate dynamic mechanism of how ABA binding to PYL10 induces PP2C phosphatase inhibiting activity, solution NMR relaxation analysis of apo-PYL10 and PYL10/ABA were conducted following backbone resonance assignments. Reduced spectrum density mapping of the backbone relaxation data revealed that PYL10 was more flexible in ABA bound form than apo-PYL10, indicating an increased conformational entropy upon ligand binding. Moreover, to illustrate conformation exchanges of PYL10 upon ABA binding, NMR line shape analysis was performed with increasing concentrations of ABA and the results indicated that PYL10 backbone conformational changes occur at different time scales.

10.1038/srep10890

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CW-EPR studies revealed different motional properties and oligomeric states of the integrin β1a transmembrane domain in detergent micelles or liposomes

Scientific Reports (2015)

Lu Yu Wei Wang Shenglong Ling Sanling Liu Liang Xiao

Integrins are heterodimeric membrane proteins that regulate essential processes: cell migration, cell growth, extracellular matrix assembly and tumor metastasis. Each integrin α or β subunit contains a large extracellular domain, a single transmembrane (TM) domain and a short cytoplasmic tail. The integrin TM domains are important for heterodimeric association and dissociation during the conversion from inactive to active states. Moreover, integrin clustering occurs by homo-oligomeric interactions between the TM helices. Here, the transmembrane and cytoplasmic (TMC) domains of integrin β1a were overexpressed and the protein was purified in detergent micelles and/or reconstituted in liposomes. To investigate the TM domain conformational properties of integrin β1a, 26 consecutive single cysteine mutants were generated for site-directed spin labeling and continuous-wave electron paramagnetic resonance (CW-EPR) mobility and accessibility analyses. The mobility analysis identified two integrin β1a-TM regions with different motional properties in micelles and a non-continuous integrin β1a-TM helix with high immobility in liposomes. The accessibility analysis verified the TM range (Val737-Lys752) of the integrin β1a-TMC in micelles. Further mobility and accessibility comparisons of the integrin β1a-TMC domains in micelles or liposomes identified distinctively different oligomeric states of integrin β1a-TM, namely a monomer embedded in detergent micelles and leucine-zipper-like homo-oligomeric clusters in liposomes.

10.1038/srep07848

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Differential Modulations of KCNQ1 by Auxiliary Proteins KCNE1 and KCNE2

Scientific Reports (2014)

Pan Li Haowen Liu Chaohua Lai Peibei Sun Wenping Zeng

KCNQ1 channels play vital roles in cardiovascular, gastric and other systems. The conductance and dynamics of KCNQ1 could be modulated by different single transmembrane helical auxiliary proteins (such as KCNE1, KCNE2 and others). In this study, detail KCNQ1 function modulations by different regions of KCNE1 or KCNE2 were examined using combinational methods of electrophysiology, immunofluorescence, solution NMR and related backbone flexibility analysis. In the presence of KCNE2 N-terminus, decreased surface expression and consequent low activities of KCNQ1 were observed. The transmembrane domains (TMDs) of KCNE1 and KCNE2 were illustrated to associate with the KCNQ1 channel in different modes: Ile64 in KCNE2-TMD interacting with Phe340 and Phe275 in KCNQ1, while two pairs of interacting residues (Phe340-Thr58 and Ala244-Tyr65) in the KCNQ1/KCNE1 complex. The KCNE1 C-terminus could modulate gating property of KCNQ1, whereas KCNE2 C-terminus had only minimal influences on KCNQ1. All of the results demonstrated different KCNQ1 function modulations by different regions of the two auxiliary proteins.

10.1038/srep04973

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Citations (14)