Structural analysis of a bacterial ankyrin-like protein secreted by Acinetobacter baumannii

In bacteria, the ankyrin-like protein AnkB helps overcome stress by regulating catalase activity when expressed under stressful conditions. As the structural properties of AnkB are largely unexplored, our understanding of various AnkB-mediated functions in bacteria remains limited. In the present study, we describe the structure of AnkB from Acinetobacter baumannii, hereafter referred to as “AbAnkB,” which has a unique tertiary configuration compared with that of other ankyrin domain-containing proteins. Structural analysis revealed that AbAnkB has a relatively long loop between AKR3 and AKR4 and an oppositely positioned α8 helix. Based on amino acid conservation and protein surface analyses, we identified a hydrophobic patch that might be critical for the function of AbAnkB. To the best of our knowledge, our study is the first to report the structure of a bacterial AnkB protein; our findings will markedly enhance our understanding of its functions in bacteria. •We report the structure of ankyrin-like protein AnkB from Acinetobacter baumannii.•AbAnkB consists of only ankyrin repeat domains.•AbAnkB features a long AKR3–4 loop containing a small α-helix.•We identified a central hydrophobic patch that may be critical for AbAnkB function.•Our findings will enhance our understanding of the functions of bacterial ankyrins-like protein.