Holliday　junction　(HJ)　is　a　four-way　structured　DNA　intermediate　in　homologous　recombination.　In　bacteria,　the　HJ-specific　binding　protein　RuvA　and　the　motor　protein　RuvB　together　form　the　RuvAB　complex　to　catalyze　HJ　branch　migration.　Pseudomonas　aeruginosa　(P.　aeruginosa,　Pa)　is　a　ubiquitous　opportunistic　bacterial　pathogen　that　can　cause　serious　infection　in　a　variety　of　host　species,　including　vertebrate　animals,　insects　and　plants.　Here,　we　describe　the　cryo-Electron　Microscopy　(cryo-EM)　structure　of　the　RuvAB-HJ　intermediate　complex　from　P.　aeruginosa.　The　structure　shows　that　two　RuvA　tetramers　sandwich　HJ　at　the　junction　center　and　disrupt　base　pairs　at　the　branch　points　of　RuvB-free　HJ　arms.　Eight　RuvB　subunits　are　recruited　by　the　RuvA　octameric　core　and　form　two　open-rings　to　encircle　two　opposite　HJ　arms.　Each　RuvB　subunit　individually　binds　a　RuvA　domain　III.　The　four　RuvB　subunits　within　the　ring　display　distinct　subdomain　conformations,　and　two　of　them　engage　the　central　DNA　duplex　at　both　strands　with　their　C-terminal　β-hairpins.　Together　with　the　biochemical　analyses,　our　structure　implicates　a　potential　mechanism　of　RuvB　motor　assembly　onto　HJ　DNA.　Copyright　©　2023　Zhang,　Zhou,　Dai,　Chao,　Liu,　Huang,　Qu　and　Lin.