Graduate School of Frontier Biosciences, Osaka University

Japanese

High-resolution pH imaging of living bacterial cell to detect local pH differences

Journal mBio, e01911-16 (2016)
Authors Morimoto YV (1, 2), Kami-Ike N (1), Miyata T (1), Kawamoto A (1), Kato T (1), Namba K (3, 2), Minamino T (3).
  1. Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan.
  2. Quantitative Biology Center, RIKEN, Suita, Osaka, Japan.
  3. Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, Japan keiichi@fbs.osaka-u.ac.jp tohru@fbs.osaka-u.ac.jp.

Title High-resolution pH imaging of living bacterial cell to detect local pH differences
PubMed 27923921
Laboratory Protonic NanoMachine Group 〈Prof. Namba〉
Abstract Protons are utilized for various biological activities such as energy transduction and cell signaling. For construction of the bacterial flagellum, a type III export apparatus utilizes ATP and proton motive force to drive flagellar protein export, but the energy transduction mechanism remains unclear. Here, we have developed a high-resolution pH imaging system to measure local pH differences within living Salmonella enterica cells, especially in close proximity to the cytoplasmic membrane and the export apparatus. The local pH near the membrane was ca. 0.2 pH unit higher than the bulk cytoplasmic pH. However, the local pH near the export apparatus was ca. 0.1 pH unit lower than that near the membrane. This drop of local pH depended on the activities of both transmembrane export components and FliI ATPase. We propose that the export apparatus acts as an H+/protein antiporter to couple ATP hydrolysis with H+ flow to drive protein export.