The opportunistic pathogen Acinetobacter baumannii is commonly associated with hospital-acquired bacteremia and respiratory infections. Antibiotic resistance is rapidly emerging in A. baumannii, posing such a risk that the World Health Organisation has listed it as a priority 1 critical organism where new antibiotic agents are urgently required. Many strains of A. baumannii express a type VI secretion system (T6SS). This molecular machine delivers antibacterial toxins directly into competitor bacteria, providing T6SS+ cells with a competitive advantage in certain niches. T6SS+ cells also express cognate immunity proteins that directly bind and neutralise effectors. One such effector-immunity pair from A. baumannii strain AB307-0294 is the Type VI DNase effector 16 (Tde16) and its cognate DNase immunity protein (Tdi16). To confirm the activity of effector Tde16, attempts were made to express and purify the predicted Tde16 DNase domain in a bacterial expression system; however, E. coli cells expressing the DNase domain were not viable. Therefore, guided by homology to other DNases, a double alanine mutant at the predicted active site was constructed (AHH to AAA) to produce Tde16AAA. Tde16AAA was non-toxic when expressed in E. coli and purification confirmed the protein was monomeric and capable of binding DNA. Purification of the full-length cognate immunity protein, Tdi16, showed that the two proteins directly interact with a likely binding stoichiometry of 1:1 and that presence of Tdi16 disrupts Tde16AAA DNA binding. The DNA binding properties of Tde16AAA are currently being investigated and crystallisation studies are underway to solve the structure of Tde16AAA, both alone and in combination with Tdi16. Exploring these effector/immunity interactions may allow for manipulation and treatment of A. baumannii infections in future. The effectors alone may also represent novel antimicrobial agents to aid in combating antimicrobial resistance.