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Cell Res. 2018 Jun;28(6):644-654. doi: 10.1038/s41422-018-0032-8. Epub 2018 Mar 27.

Succinate-acetate permease from Citrobacter koseri is an anion channel that unidirectionally translocates acetate.

Qiu B1,2, Xia B3,4, Zhou Q5, Lu Y1,2, He M1,2, Hasegawa K6, Ma Z7, Zhang F8, Gu L8, Mao Q3,4, Wang F9, Zhao S1,5, Gao Z10, Liao J11,12.

Author information

1
School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China.
2
Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, 200031, China.
3
CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China.
4
University of Chinese Academy of Sciences, 19A Yuquan Road, Beijing, 100049, China.
5
iHuman Institute, ShanghaiTech University, Shanghai, 201210, China.
6
Protein Crystal Analysis Division, Japan Synchrotron Radiation Research Institute, Hyogo, 679-5198, Japan.
7
Key Laboratory of Functional Molecular Engineering of Guangdong Province, School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong, 510640, China.
8
State Key Laboratory of Microbial Technology, Shandong University, Jinan, Shandong, 250100, China.
9
Wuxi Biortus Biosciences Co., Ltd, Wuxi, Jiangsu, 214437, China.
10
CAS Key Laboratory of Receptor Research, State Key Laboratory of Drug Research, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, 201203, China. zbgao@simm.ac.cn.
11
School of Life Science and Technology, ShanghaiTech University, Shanghai, 201210, China. liaojun@shanghaitech.edu.cn.
12
Institute of Biochemistry and Cell Biology, Chinese Academy of Sciences, 320 Yueyang Road, Shanghai, 200031, China. liaojun@shanghaitech.edu.cn.

Abstract

Acetate is an important metabolite in metabolism and cell signaling. Succinate-Acetate Permease (SatP) superfamily proteins are known to be responsible for acetate transport across membranes, but the nature of this transport remains unknown. Here, we show that the SatP homolog from Citrobacter koseri (SatP_Ck) is an anion channel that can unidirectionally translocate acetate at rates of the order of ~107 ions/s. Crystal structures of SatP_Ck in complex with multiple acetates at 1.8 Å reveal that the acetate pathway consists of four acetate-binding sites aligned in a single file that are interrupted by three hydrophobic constrictions. The bound acetates at the four sites are each orientated differently. The acetate at the cytoplasmic vestibule is partially dehydrated, whereas those in the main pore body are fully dehydrated. Aromatic residues within the substrate pathway may coordinate translocation of acetates via anion-π interactions. SatP_Ck reveals a new type of selective anion channel and provides a structural and functional template for understanding organic anion transport.

PMID:
29588525
PMCID:
PMC5993801
[Available on 2019-06-01]
DOI:
10.1038/s41422-018-0032-8

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