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Todokoro Y, Kang SJ, Suzuki T, Ikegami T, Kainosho M, Yoshida M, Fujiwara T, Akutsu H. Chemical Conformation of the Essential Glutamate Site of the c-Ring within Thermophilic Bacillus F oF 1-ATP Synthase Determined by Solid-State NMR Based on its Isolated c-Ring Structure. J Am Chem Soc 2022; 144:14132-14139. [PMID: 35905443 DOI: 10.1021/jacs.2c03580] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Proton translocation through the membrane-embedded Fo component of F-type ATP synthase (FoF1) is facilitated by the rotation of the Fo c-subunit ring (c-ring), carrying protons at essential acidic amino acid residues. Cryo-electron microscopy (Cryo-EM) structures of FoF1 suggest a unique proton translocation mechanism. To elucidate it based on the chemical conformation of the essential acidic residues of the c-ring in FoF1, we determined the structure of the isolated thermophilic Bacillus Fo (tFo) c-ring, consisting of 10 subunits, in membranes by solid-state NMR. This structure contains a distinct proton-locking conformation, wherein Asn23 (cN23) CγO and Glu56 (cE56) CδOH form a hydrogen bond in a closed form. We introduced stereo-array-isotope-labeled (SAIL) Glu and Asn into the tFoc-ring to clarify the chemical conformation of these residues in tFoF1-ATP synthase (tFoF1). Two well-separated 13C signals could be detected for cN23 and cE56 in a 505 kDa membrane protein complex, respectively, thereby suggesting the presence of two distinct chemical conformations. Based on the signal intensity and structure of the tFoc-ring and tFoF1, six pairs of cN23 and cE56 surrounded by membrane lipids take the closed form, whereas the other four in the a-c interface employ the deprotonated open form at a proportion of 87%. This indicates that the a-c interface is highly hydrophilic. The pKa values of the four cE56 residues in the a-c interface were estimated from the cN23 signal intensity in the open and closed forms and distribution of polar residues around each cE56. The results favor a rotation of the c-ring for ATP synthesis.
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Affiliation(s)
- Yasuto Todokoro
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita 565-0871, Japan.,Technical Support Division, School of Science, Osaka University, 1-1 Machikaneyama-cho, Toyonaka 560-0043, Japan
| | - Su-Jin Kang
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita 565-0871, Japan.,Department of Biophysics and Chemical Biology, Seoul National University, Gwanak-Gu, Seoul 151-742, Republic of Korea.,College of Pharmacy, Dongduk Women's University, Seoul 02748, Republic of Korea
| | - Toshiharu Suzuki
- Laboratory for Chemistry and Life Science, Institute of Innovative Research, Tokyo Institute of Technology, Midori-ku, Yokohama 226-0026, Japan
| | - Takahisa Ikegami
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehirocho, Tsurumi-ku, Yokohama 230-0045, Japan
| | - Masatsune Kainosho
- Department of Chemistry, Graduate School of Science, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan
| | - Masasuke Yoshida
- Department of Molecular Bioscience, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto 603-8555, Japan
| | - Toshimichi Fujiwara
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita 565-0871, Japan
| | - Hideo Akutsu
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita 565-0871, Japan.,Department of Biophysics and Chemical Biology, Seoul National University, Gwanak-Gu, Seoul 151-742, Republic of Korea.,Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehirocho, Tsurumi-ku, Yokohama 230-0045, Japan
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Kang SJ, Todokoro Y, Bak S, Suzuki T, Yoshida M, Fujiwara T, Akutsu H. Direct assignment of 13C solid-state NMR signals of TF oF 1 ATP synthase subunit c-ring in lipid membranes and its implication for the ring structure. J Biomol NMR 2018; 70:53-65. [PMID: 29197977 DOI: 10.1007/s10858-017-0158-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Accepted: 11/28/2017] [Indexed: 06/07/2023]
Abstract
FoF1-ATP synthase catalyzes ATP hydrolysis/synthesis coupled with a transmembrane H+ translocation in membranes. The Fo c-subunit ring plays a major role in this reaction. We have developed an assignment strategy for solid-state 13C NMR (ssNMR) signals of the Fo c-subunit ring of thermophilic Bacillus PS3 (TFo c-ring, 72 residues), carrying one of the basic folds of membrane proteins. In a ssNMR spectrum of uniformly 13C-labeled sample, the signal overlap has been a major bottleneck because most amino acid residues are hydrophobic. To overcome signal overlapping, we developed a method designated as COmplementary Sequential assignment with MInimum Labeling Ensemble (COSMILE). According to this method, we generated three kinds of reverse-labeled samples to suppress signal overlapping. To assign the carbon signals sequentially, two-dimensional Cα(i+1)-C'Cα(i) correlation and dipolar assisted rotational resonance (DARR) experiments were performed under magic-angle sample spinning. On the basis of inter- and intra-residue 13C-13C chemical shift correlations, 97% of Cα, 97% of Cβ and 92% of C' signals were assigned directly from the spectra. Secondary structure analysis predicted a hairpin fold of two helices with a central loop. The effects of saturated and unsaturated phosphatidylcholines on TFo c-ring structure were examined. The DARR spectra at 15 ms mixing time are essentially similar to each other in saturated and unsaturated lipid membranes, suggesting that TFo c-rings have similar structures under the different environments. The spectrum of the sample in saturated lipid membranes showed better resolution and structural stability in the gel state. The C-terminal helix was suggested to locate in the outer layer of the c-ring.
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Affiliation(s)
- Su-Jin Kang
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, 565-0871, Japan
- Department of Biophysics and Chemical Biology, Seoul National University, Kwanak-Gu, Seoul, 151-742, Republic of Korea
| | - Yasuto Todokoro
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, 565-0871, Japan
| | - Suyeon Bak
- Department of Biophysics and Chemical Biology, Seoul National University, Kwanak-Gu, Seoul, 151-742, Republic of Korea
| | - Toshiharu Suzuki
- Department of Applied Chemistry, School of Engineering, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan
| | - Masasuke Yoshida
- Department of Molecular Bioscience, Kyoto Sangyo University, Kamigamo-Motoyama, Kyoto, 603-8555, Japan
| | - Toshimichi Fujiwara
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, 565-0871, Japan
| | - Hideo Akutsu
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, 565-0871, Japan.
- Department of Biophysics and Chemical Biology, Seoul National University, Kwanak-Gu, Seoul, 151-742, Republic of Korea.
- Graduate School of Medical Life Science, Yokohama City University, 1-7-29 Suehirocho, Tsurumi-ku, Yokohama, 230-0045, Japan.
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