Biography

I specialize in the structural and functional characterization of bacterial and eukaryotic membrane proteins, including ion channels and transporters. Over two decades of research, I have developed extensive expertise across the full gene-to-structure pipeline—encompassing protein expression, purification, functional reconstitution into liposomes and nanodiscs, and high-resolution structure determination via X-ray crystallography and cryo-EM. Currently, at the Special Project Group, I lead structural biology initiatives for challenging targets, utilizing lipidic cubic phase (LCP) crystallization, detergent optimization, and antibody complexes to resolve small or low-diffracting membrane proteins that fall outside typical cryo-EM size thresholds. Additionally, I serve as co-PI on an NIDCR-funded R21 project focused on bacterial membrane protein structural and functional characterization.

Publications

Crystallographic Characterization of Sodium Ions in a Bacterial Leucine/Sodium Symporter

Akira Karasawa, Haijiao Liu, Matthias Quick, Wayne A. Hendrickson, Qun Liu

Crystals, Vol. 13, Issue 2, Pages 183

2023 January

Multi-crystal native-SAD phasing at 5 keV with a helium environment

Akira Karasawa, Babak Andi, Martin R. Fuchs, Wuxian Shi, Sean McSweeney, Wayne A. Hendrickson, Qun Liu

IUCrJ, Vol. 9, Issue 6, Pages 768-777

2022 November

High-throughput YO-PRO-1 Uptake Assay for P2X7 Receptors Expressed in HEK Cells

Akira Karasawa, Toshimitsu Kawate

BIO-PROTOCOL, Vol. 8, Issue 14

2018 January

The P2X7 receptor forms a dye-permeable pore independent of its intracellular domain but dependent on membrane lipid composition.

Akira Karasawa, Kevin Michalski, Polina Mikhelzon, Toshimitsu Kawate

eLife, Vol. 6

2017 September

Expression and Purification of a Mammalian P2X7 Receptor from Sf9 Insect Cells.

Akira Karasawa, Toshimitsu Kawate

Bio-protocol, Vol. 7, Issue 17

2017 September

Structural basis for subtype-specific inhibition of the P2X7 receptor.

Akira Karasawa, Toshimitsu Kawate

eLife, Vol. 5

2016 December

Physicochemical factors controlling the activity and energy coupling of an ionic strength-gated ATP-binding cassette (ABC) transporter.

Akira Karasawa, Lotteke J.Y.M. Swier, Marc C.A. Stuart, Jos Brouwers, Bernd Helms, Bert Poolman

The Journal of biological chemistry, Vol. 288, Issue 41, Pages 29862-29871

2013 August

Functional characterization of amphipathic α-helix in the osmoregulatory ABC transporter OpuA.

Nadia Gul, Gea Schuurman-Wolters, Akira Karasawa, Bert Poolman

Biochemistry, Vol. 51, Issue 25, Pages 5142-5152

2012 June

Cystathionine β-synthase (CBS) domains 1 and 2 fulfill different roles in ionic strength sensing of the ATP-binding cassette (ABC) transporter OpuA.

Akira Karasawa, Guus B. Erkens, Ronnie P.-A. Berntsson, Renee Otten, Gea K. Schuurman-Wolters, Frans A.A. Mulder, Bert Poolman

The Journal of biological chemistry, Vol. 286, Issue 43, Pages 37280-37291

2011 August

Ligand binding and crystal structures of the substrate-binding domain of the ABC transporter OpuA.

Justina C. Wolters, Ronnie P-A. Berntsson, Nadia Gul, Akira Karasawa, Andy-Mark W. H. Thunnissen, Dirk-Jan Slotboom, Bert Poolman

PloS one, Vol. 5, Issue 4, Pages e10361

2010 April

Intermolecular cross-linking of monomers in Helicobacter pylori Na+/H+ antiporter NhaA at the dimer interface inhibits antiporter activity.

Akira Karasawa, Keiji Mitsui, Masafumi Matsushita, Hiroshi Kanazawa

The Biochemical journal, Vol. 426, Issue 1, Pages 99-108

2010 January

Functional assembly of the Na+/H+ antiporter of Helicobacter pylori from partial fragments in vivo.

Akira Karasawa, Keiji Mitsui, Masafumi Matsushita, Hiroshi Kanazawa

Biochemistry, Vol. 46, Issue 49, Pages 14272-14283

2007 November

Detection of oligomerization and conformational changes in the Na+/H+ antiporter from Helicobacter pylori by fluorescence resonance energy transfer.

Akira Karasawa, Yumi Tsuboi, Hiroki Inoue, Rie Kinoshita, Norihiro Nakamura, Hiroshi Kanazawa

The Journal of biological chemistry, Vol. 280, Issue 51, Pages 41900-41911

2005 October