title: Orientia tsutsugamushi Ank9 is a multifunctional effector that utilizes a novel GRIP-like Golgi localization domain for Golgi-to-endoplasmic reticulum trafficking and interacts with host COPB2.
abstract: Orientia tsutsugamushi causes scrub typhus, a potentially fatal infection that afflicts 1 million people annually. This obligate intracellular bacterium boasts one of the largest microbial arsenals of ankyrin repeat-containing protein (Ank) effectors, most of which target the endoplasmic reticulum (ER) by undefined mechanisms. Ank9 is the only one proven to function during infection. Here, we demonstrate that Ank9 bears a motif that mimics the GRIP domain of eukaryotic golgins and is necessary and sufficient for its Golgi localization. Ank9 reaches the ER exclusively by retrograde trafficking from the Golgi. Consistent with this observation, it binds COPB2, a host protein that mediates Golgi-to-ER transport. Ank9 destabilizes the Golgi and ER in a Golgi localization domain-dependent manner and induces the activating transcription factor 4-dependent unfolded protein response. The Golgi is also destabilized in cells infected with O. tsutsugamushi or treated with COPB2 small interfering RNA. COPB2 reduction and/or the cellular events that it invokes, such as Golgi destabilization, benefit Orientia replication. Thus, Ank9 or bacterial negative modulation of COPB2 might contribute to the bacterium's intracellular replication. This report identifies a novel microbial Golgi localization domain, links Ank9 to the ability of O. tsutsugamushi to perturb Golgi structure, and describes the first mechanism by which any Orientia effector targets the secretory pathway.
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.|Department of Biology, Virginia State University, Petersburg, VA, USA.
authors.forename: Andrea R
authors.initials: AR
authors.lastname: Beyer
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Kyle G
authors.initials: KG
authors.lastname: Rodino
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: VieBrock
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Green
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.|Kaztronix, McLean, VA, USA.
authors.forename: Brittney K
authors.initials: BK
authors.lastname: Tegels
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Lee D
authors.initials: LD
authors.lastname: Oliver
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Richard T
authors.initials: RT
authors.lastname: Marconi
authors.affiliation: Department of Microbiology and Immunology, Virginia Commonwealth University School of Medicine, Richmond, VA, USA.
authors.forename: Jason A
authors.identifier: 0000-0003-2778-5066
authors.initials: JA
authors.lastname: Carlyon
mesh_terms: D051701:Activating Transcription Factor 4 / Q000378:metabolism; D017487:Ankyrins / Q000378:metabolism*; D001426:Bacterial Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D020756:Coatomer Protein / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D012285:Orientia tsutsugamushi / Q000472:pathogenicity*; D011485:Protein Binding / Q000502:physiology; D000072417:Protein Domains / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D012612:Scrub Typhus / Q000382:microbiology; D056811:Unfolded Protein Response / Q000502:physiology
chemical_list: C497109:ATF4 protein, human; D017487:Ankyrins; D001426:Bacterial Proteins; C000619331:COPB2 protein, human; D020756:Coatomer Protein; D034741:RNA, Small Interfering; D051701:Activating Transcription Factor 4
keywords: Golgi localization domain; Rickettsia; ankyrin repeat-containing proteins; bacterial effectors; intracellular bacteria; retrograde trafficking