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Title: The soluble cytoplasmic N-terminal domain of the FocA channel gates bidirectional formate translocation
Author(s): Kammel, Michelle
Hunger, Doreen
Sawers, Robert Gary
Issue Date: 2021
Type: Article
Language: English
Abstract: FocA belongs to the pentameric FNT (formate-nitrite transporter) superfamily of anion channels, translocating formate bidirectionally across the cytoplasmic membrane of Escherichia coli and other microorganisms. While the membrane-integral core of FocA shares considerable amino acid sequence conservation with other FNT family members, the soluble cytoplasmic N-terminal domain does not. To analyze the potential biochemical function of FocA’s N-terminal domain in vivo, we constructed truncation derivatives and amino acid-exchange variants, and determined their ability to translocate formate across the membrane of E. coli cells by monitoring intracellular formate levels using a formate-sensitive reporter system. Analysis of strains synthesizing these FocA variants provided insights into formate efflux. Strains lacking the ability to generate formate intracellularly allowed us to determine whether these variants could import formate or its toxic chemical analog hypophosphite. Our findings reveal that the N-terminal domain of FocA is crucial for bidirectional FocA-dependent permeation of formate across the membrane. Moreover, we show that an amino acid sequence motif and secondary structural features of the flexible N-terminal domain are important for formate translocation, and efflux/influx is influenced by pyruvate formate-lyase. The soluble N-terminal domain is, therefore, essential for bidirectional formate translocation by FocA, suggesting a “gate-keeper” function controlling anion accessibility.
Open Access: Open access publication
License: (CC BY 4.0) Creative Commons Attribution 4.0(CC BY 4.0) Creative Commons Attribution 4.0
Sponsor/Funder: Publikationsfonds MLU
Journal Title: Molecular microbiology
Publisher: Wiley-Blackwell
Publisher Place: Oxford [u.a.]
Volume: 115
Issue: 4
Original Publication: 10.1111/mmi.14641
Page Start: 758
Page End: 773
Appears in Collections:Open Access Publikationen der MLU

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