Research progress: Integration of bacterial expansin-like proteins into cellulosome promotes the cellulose degradation

[2015.10.31] Cellulosome is the most efficient multi-enzyme complex for lignocellulose degradation. Recently, we make progress in the research of cellulosome components, and the results are published on Appl. Microbiol. Biotechnol. on Oct. 31.

Cellulosome has very complex components to synergistically degrade the lignocellulose. We found that there are two expansin-like genes in the genome of Clostridium clariflavum DSM 19732, and each of the two genes has a dockerin module which suggest that they are components of cellulosome. It is well established that bacterial expansin-like proteins can synergistically promote the cellulose degradation by cellulases although they do not have cellulase activity. We studied the function of the two dockerin-bearing expansin-like proteins. When the free recombinant expansin-like protein modules were mixed with native cellulosomes from Clostridium thermocellum or Clostridium clariflavum, they can significantly increase the activity of cellulosomes, which demonstrates that the two protein modules are functional expansin-like proteins. When the two expansin-like protein modules are integrated into a trivalent designer cellulosome, they can further promote the cellulase activity compared to free expansin-like modules. The sequence and structure analysis of the two proteins indicated that they have same functional mechanism as other well-known bacterial expansin-like protein. Our study demonstrated that bacterial expansin-like proteins can promote the activity of cellulosome by integrating into cellulosome, and the new functional implications of bacterial expansin-like proteins and cellulosomes are also discussed in the paper.

The research was supervised by Prof. Qiu Cui and Prof. Yingang Feng, and was financially supported by the 973 Program from Ministry of Science and Technology of China and the National Natural Science Foundation of China.

NCBI PubMed 

Chao Chen, Zhenling Cui, Xiangfei Song, Ya-Jun Liu, Qiu Cui*, and Yingang Feng* (2015) Integration of bacterial expansin-like proteins into cellulosome promotes the cellulose degradation. Appl. Microbiol. Biotechnol. In press. [PMID: 26521249] [Full text (Publisher website)]