RqlH and RqlI proteins physically interact.

MG1655 bacteria that express full-length FLAG-tagged RqlI and HA-tagged RqlH (either full-length RqlH or the 1–509 truncation mutant lacking the PRTase domain) were grown for 4 h, then an additional hour in the presence of IPTG and arabinose, prior to lysis under non-denaturing conditions. As a control, MG1655 carrying the empty vectors pRR48 and pBAD33 were processed in parallel. Lysates were immunoprecipitated using anti-FLAG or anti-HA antibodies, and immunoprecipitates were resolved by SDS-PAGE in preparation for western blot analysis. Aliquots (5%) of the cell lysates that were used as input for the immunoprecipitations were also resolved. Immunoblots (IB) were probed using antibodies specific for the FLAG or HA epitopes or for LacI, as indicated.