PT  - JOURNAL ARTICLE
AU  - Yiming Niu
AU  - Xiao Tao
AU  - George Vaisey
AU  - Paul Dominic B. Olinares
AU  - Hanan Alwaseem
AU  - Brian T. Chait
AU  - Roderick MacKinnon
TI  - Analysis of the Mechanosensor Channel Functionality of TACAN
AID  - 10.1101/2021.06.11.448078
DP  - 2021 Jan 01
TA  - bioRxiv
PG  - 2021.06.11.448078
4099  - http://biorxiv.org/content/early/2021/06/12/2021.06.11.448078.short
4100  - http://biorxiv.org/content/early/2021/06/12/2021.06.11.448078.full
AB  - Mechanosensitive ion channels mediate transmembrane ion currents activated by mechanical forces. A mechanosensitive ion channel called TACAN was recently reported. We began to study TACAN with the intent to understand how it senses mechanical forces and functions as an ion channel. Using cellular patch-recording methods we failed to identify mechanosensitive ion channel activity. Using membrane reconstitution methods we found that TACAN, at high protein concentrations, produces non-selective, heterogeneous conduction levels that are not mechanosensitive and are most consistent with disruptions of the lipid bilayer. We determined the structure of TACAN using single particle cryo-EM and observe that it forms a symmetrical dimeric transmembrane protein. Each protomer contains an intracellular-facing cleft with a coenzyme-A co-factor, confirmed by mass spectrometry. The TACAN protomers are related in 3-dimensional structure to a fatty acid elongase, ELOVL. Whilst its physiological function remains unclear, we anticipate that TACAN is not a mechanosensitive ion channel.Competing Interest StatementThe authors have declared no competing interest.