|Yennamalli, Ragothaman - Iowa State University|
|Rader, Andrew - Indiana University-Purdue University|
|Wolt, Jeffrey - Iowa State University|
Submitted to: Annual Biophysical Meeting
Publication Type: Abstract Only
Publication Acceptance Date: 10/18/2010
Publication Date: 3/9/2011
Citation: Yennamalli, R.M., Rader, A.J., Wolt, J.D., Sen, T.Z. 2011. Sequence, structure and dynamics analysis of thermostability in endoglucanases. Annual Biophysical Meeting. 2011(1):134.
Technical Abstract: Endoglucanases are crucial enzymes used in the production of biofuels from cellulosic biomass, a process that requires thermostability at high processing temperatures. Despite the economic importance of these industrial proteins, we currently lack a basic understanding of how some endoglucanases can efficiently function at elevated processing temperatures, while others with the same fold have substantial reduction in activity. Here we explore the origins of thermostability in endoglucanases from sequence, structure, and dynamics perspectives using thermostable and mesostable protein sets. We performed a comparative sequence and structure analysis for thermophilic and mesophilic endoglucanases in (a/B)8, B-jelly roll, and (a/a)6 folds, followed by a dynamics analysis of the (a/B)8 fold using elastic network models. We observed that thermophilic endoglucanases and their mesophilic counterparts differ significantly in their amino acid compositions. Interestingly, these compositional differences are specific to protein folds and enzyme families and lead to modification in hydrophobic, aromatic, and ionic interactions in a fold-dependent fashion. We then focused specifically on a pair of thermostable and mesostable endoglucanases for a detailed dynamics analysis. It is often the case that thermophiles have shorter loops than their mesophilic counterparts, which was suggested to impart thermostability. In our case, however, the thermophile surprisingly possessed three insertions in the mesophilic loop regions and therefore has longer loops. The comparative structural dynamics analysis using elastic network models of (a/B)8 fold indicate that these three loops may contribute to the thermostability by modulating the direction of correlated motions between the catalytic residues (acid/base donor and nucleophile). We also observed that the thermostable protein showed larger dynamic domains than its mesostable counterpart, which suggests that cooperative dynamics is a critical contributing factor to thermostability.