title: Identification of Anaplasma marginale type IV secretion system effector proteins.
abstract: BACKGROUND
  Anaplasma marginale, an obligate intracellular alphaproteobacterium in the order Rickettsiales, is a tick-borne pathogen and the leading cause of anaplasmosis in cattle worldwide. Complete genome sequencing of A. marginale revealed that it has a type IV secretion system (T4SS). The T4SS is one of seven known types of secretion systems utilized by bacteria, with the type III and IV secretion systems particularly prevalent among pathogenic Gram-negative bacteria. The T4SS is predicted to play an important role in the invasion and pathogenesis of A. marginale by translocating effector proteins across its membrane into eukaryotic target cells. However, T4SS effector proteins have not been identified and tested in the laboratory until now.
  
  
  RESULTS
  By combining computational methods with phylogenetic analysis and sequence identity searches, we identified a subset of potential T4SS effectors in A. marginale strain St. Maries and chose six for laboratory testing. Four (AM185, AM470, AM705 [AnkA], and AM1141) of these six proteins were translocated in a T4SS-dependent manner using Legionella pneumophila as a reporter system.
  
  
  CONCLUSIONS
  The algorithm employed to find T4SS effector proteins in A. marginale identified four such proteins that were verified by laboratory testing. L. pneumophila was shown to work as a model system for A. marginale and thus can be used as a screening tool for A. marginale effector proteins. The first T4SS effector proteins for A. marginale have been identified in this work.
authors.affiliation: School of Electrical Engineering and Computer Science, Washington State University, Pullman, Washington, United States of America.
authors.forename: Svetlana
authors.initials: S
authors.lastname: Lockwood
authors.forename: Daniel E
authors.initials: DE
authors.lastname: Voth
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Brayton
authors.forename: Paul A
authors.initials: PA
authors.lastname: Beare
authors.forename: Wendy C
authors.initials: WC
authors.lastname: Brown
authors.forename: Robert A
authors.initials: RA
authors.lastname: Heinzen
authors.forename: Shira L
authors.initials: SL
authors.lastname: Broschat
mesh_terms: D037361:Adenylate Cyclase Toxin / Q000378:metabolism; D042322:Anaplasma marginale / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D001681:Biological Assay; D002417:Cattle; D023061:Gene Order / Q000235:genetics; D016680:Genome, Bacterial / Q000235:genetics; D021381:Protein Transport; D015203:Reproducibility of Results
chemical_list: D037361:Adenylate Cyclase Toxin; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems