Author(s)

Arnaud Vanden Broeck¹, Eric Sauvage², Bernard Joris^1*, Colette Duez^1*

¹Institut de Chimie, Centre for Protein Engineering, University of Liège, Liège, Belgium.
²Institut de Physique, Centre for Protein Engineering, University of Liège, Liège, Belgium.

Purpose: The PBP4* is a Penicillin Binding Protein belonging to the class C of AmpH type whose function remains poorly understood. This study aimed to evaluate the biophysical and enzymatic properties of the Bacillus subtilis PBP4* to gain insights into its role in the context of bacterial cell wall recycling. Methods: To characterize the PBP4*, the full-length PBP4* and its N-terminal penicillin-binding domain have been produced in Escherichia coli and purified. Results: A comparison of biophysical properties has shown that both recombinant proteins are monomeric in solution and retain the same thermal stability. On the other hand, the D-alanine methyl esterase activity detected with the full-length PBP4* is impeded by the cleavage of the 92 amino acid C-terminal domain. The esterase activity of the full-length PBP4* strates a clear D-stereospecificity. The PBP4* is also active on B. subtilis cell walls bearing teichoic acids, compounds commonly substituted with D-alanine residues. Conclusions: Our results are in agreement with the hypothesis that PBP4* could play a role in recycling cell wall components, as previously suggested.

B. subtilis PBP4*, Class-C PBP, D-Stereospecific Esterase

Broeck, A. , Sauvage, E. , Joris, B. and Duez, C. (2019) Characterization of the Bacillus subtilis Penicillin-Binding Protein PBP4. Advances in Microbiology, 9, 164-176. doi: 10.4236/aim.2019.93013.