Pulsed High-Field Gradient in Vivo NMR Spectroscopy to Measure Diffusional Water Permeability in Corynebacterium glutamicum

✍ Scribed by Siegfried M Schoberth; Nils-Karsten Bär; Reinhard Krämer; Jörg Kärger

• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 107 KB
• Volume: 279
• Category: Article
• ISSN: 0003-2697
• DOI: 10.1006/abio.1999.4450

✦ Synopsis

Pulsed high-field gradient in vivo NMR spectroscopy was used to measure diffusional water permeability in cell suspensions of the Gram-positive bacterium Corynebacterium glutamicum. Two different regions of H 2 O mobility were detected. One was characterized by the apparent coefficient of self-diffusion, D 1 app ‫؍‬ (4.6 -12.7) ؋ 10 ؊8 cm 2 s ؊1 , depending on the observation time t. The other region was characterized by D 2 ‫؍‬ 1.4 ؋ 10 ؊5 cm 2 s ؊1 . The value of D 2 was similar to the diffusion coefficient of H 2 O in free water and in extracellular biological fluids. Restricted diffusion could be demonstrated for the slower process (D 1 ). It was attributed to the cytoplasm of the cells. The membrane permeability, P d H2 O , for C. glutamicum was (4.8 ؎ 0.4) ؋ 10 ؊3 cm s ؊1 . It compared favorably with values reported for human erythrocytes and was higher by a factor of about 100 compared to the diffusional permeability for ethanol, P d ethanol , in Zymomonas mobilis. Addition of HgCl 2 , a water channel inhibitor in eukaryotes, decreased P d H2 O in C. glutamicum by a factor of ϳ8. To our knowledge, these are the first functional studies of water transport in prokaryotes that yielded quantitative data, viz., transmembrane water permeability expressed through D H2 O and P d H2 O .