Brucella NyxA and NyxB dimerization enhances effector function during infection.

Brucella abortus is the cause of one of the most prevalent zoonoses worldwide. We have recently discovered two translocated effectors, NyxA and NyxB, that contribute to the late stages of the infectious cycle. Although their structure was solved, the importance of their interactions and dimeric states remains unknown. We found that NyxA and NyxB directly interact and that their dimerization is essential for their function during infection. We show that monomeric forms of the Nyx effectors still interact with their host cellular target, the deSUMOylase sentrin-specific protease 3 (SENP3) but are less able than the dimers to delocalize SENP3 from the nucleoli. This study provides new insights into the intra- and inter-effector molecular interactions during Brucella pathogenesis.