Anaplasma phagocytophilum APH_0032 is expressed late during infection and localizes to the pathogen-occupied vacuolar membrane

Microb Pathog. 2010 Nov;49(5):273-84. doi: 10.1016/j.micpath.2010.06.009. Epub 2010 Jun 30.


Anaplasma phagocytophilum infects neutrophils and myeloid, endothelial, and tick cell lines to reside within a host cell-derived vacuole that is indispensible for its survival. Here, we identify APH_0032 as an Anaplasma-derived protein that associates with the A. phagocytophilum-occupied vacuolar membrane (AVM). APH_0032 is a 66.1 kDa acidic protein that electrophoretically migrates with an apparent molecular weight of 130 kDa. It contains a predicted transmembrane domain and tandemly arranged direct repeats that comprise 46% of the protein. APH_0032 is undetectable on Anaplasma organisms bound to the surfaces of HL-60 cells, but is detected on the AVM and surfaces of intravacuolar bacteria beginning 24 h post-infection. APH_0032 localizes to the AVM in HL-60, THP-1, HMEC-1, and ISE6 cells. APH_0032, along with APH_1387, which encodes a confirmed AVM protein, is transcribed during A. phagocytophilum infection of tick salivary glands and murine neutrophils. APH_0032 localizes to the AVM in neutrophils recovered from infected mice. The Legionella pneumophila Dot/IcM type IV secretion system (T4SS) can heterologously secrete a CyaA-tagged version of the A. phagocytophilum VirB/D T4SS effector, AnkA, but fails to secrete CyaA-tagged APH_0032 or APH_1387. These data confirm APH_0032 as an Anaplasma-derived AVM protein and hint that neither it nor APH_1387 are T4SS effectors.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Anaplasma phagocytophilum / pathogenicity*
  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / metabolism*
  • Cells, Cultured
  • Gene Expression Profiling
  • Gene Expression Regulation, Bacterial*
  • Host-Pathogen Interactions*
  • Humans
  • Intracellular Membranes / chemistry*
  • Legionella pneumophila / genetics
  • Legionella pneumophila / metabolism
  • Membrane Transport Proteins / metabolism
  • Mice
  • Molecular Sequence Data
  • Molecular Weight
  • Neutrophils / microbiology
  • Protein Structure, Tertiary
  • Tandem Repeat Sequences
  • Ticks
  • Transcription, Genetic
  • Vacuoles / chemistry*
  • Vacuoles / microbiology*


  • Bacterial Proteins
  • Membrane Transport Proteins