Fukuda, R. University of Tokyo, rfukuda@ori.u-tokyo.ac.jp
Nagata, T. University of Tokyo, Nagata@ori.u-tokyo.ac.jp
Kirchman, D. University of Delaware, kirchman@udel.edu
Koike, I. University of Tokyo, Koike@ori.u-tokyo.ac.jp

Recent research has found that bacterial membrane proteins dominate the dissolved protein pool in both surface and deep oceans, but the process and mechanisms by which these proteins accumulate in seawater remain unknown. We tested the hypothesis that bacterial membrane proteins resist microbial degradation and are selectively preserved in seawater. Marine bacterial cells (Vibrio) were disrupted by sonication and used as substrate for microbial degradation. SDS-PAGE analysis showed a large number of protein bands (smears) at the beginning of the experiment. After the incubation (2 months), only a few protein bands were detected, one of which corresponded to the outer membrane protein isolated from the same bacterium. We also examined degradation of bacterial membrane proteins radiolabeled with 14C or 3H leucine. Data showed that membrane proteins are less easily degraded than soluble proteins. However, after the extraction of proteins from membrane components, these proteins were degraded as easily as soluble proteins. These results are consistent with the hypothesis that bacterial membrane proteins resist enzymatic hydrolysis because of steric protection by membrane matrix.
Day: Thursday, Feb. 4
Time: Poster
Location: Sweeney Center
Code: SS33TH1166S