title: Chlamydia pneumoniae effector chlamydial outer protein N sequesters fructose bisphosphate aldolase A, providing a benefit to bacterial growth.
abstract: BACKGROUND
  Pathogenic chlamydiae are obligate intracellular pathogens and have adapted successfully to human cells, causing sexually transmitted diseases or pneumonia. Chlamydial outer protein N (CopN) is likely a critical effector protein secreted by the type III secretion system in chlamydiae, which manipulates host cells. However, the mechanisms of its action remain to be clarified. In this work, we aimed to identify previously unidentified CopN effector target in host cells.
  
  
  RESULTS
  We first performed a pull-down assay with recombinant glutathione S-transferase (GST) fusion CopN proteins (GST-CpCopN: Chlamydia pneumoniae TW183, GST-CtCopN: Chlamydia trachomatis D/UW-3/CX) as "bait" and soluble lysates obtained from human immortal epithelial HEp-2 cells as "prey", followed by SDS-PAGE with mass spectroscopy (MS). We found that a host cell protein specifically bound to GST-CpCopN, but not GST-CtCopN. MS revealed the host protein to be fructose bisphosphate aldolase A (aldolase A), which plays a key role in glycolytic metabolism. We also confirmed the role of aldolase A in chlamydia-infected HEp-2 cells by using two distinct experiments for gene knockdown with an siRNA specific to aldolase A transcripts, and for assessment of glycolytic enzyme gene expression levels. As a result, both the numbers of chlamydial inclusion-forming units and RpoD transcripts were increased in the chlamydia-infected aldolase A knockdown cells, as compared with the wild-type HEp-2 cells. Meanwhile, chlamydial infection tended to enhance expression of aldolase A.
  
  
  CONCLUSIONS
  We discovered that one of the C. pneumoniae CopN targets is the glycolytic enzyme aldolase A. Sequestering aldolase A may be beneficial to bacterial growth in infected host cells.
authors.affiliation: Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, 060-0812, Japan. kasumi_ishida@ec.hokudai.ac.jp.|Research Fellow of Japan Society for the Promotion of Science, Tokyo, 102-0083, Japan. kasumi_ishida@ec.hokudai.ac.jp.
authors.forename: Kasumi
authors.initials: K
authors.lastname: Ishida
authors.affiliation: Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, 060-0812, Japan. matsuo@hs.hokudai.ac.jp.
authors.forename: Junji
authors.initials: J
authors.lastname: Matsuo
authors.affiliation: Department of Biomedical Informatics, Osaka University Graduate School of Medicine, Suita, Osaka, 565-0871, Japan. yyamamoto@iph.pref.osaka.jp.|Japan Science and Technology Agency/Japan International Cooperation Agency, Science and Technology Research Partnership for Sustainable Development (JST/JICA, SATREPS), Osaka, Japan. yyamamoto@iph.pref.osaka.jp.|Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka, 537-0025, Japan. yyamamoto@iph.pref.osaka.jp.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Yamamoto
authors.affiliation: Department of Medical Laboratory Science, Faculty of Health Sciences, Hokkaido University, Sapporo, Hokkaido, 060-0812, Japan. hiroyuki@med.hokudai.ac.jp.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Yamaguchi
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000378:metabolism; D002460:Cell Line; D002690:Chlamydia Infections / Q000378:metabolism; D002692:Chlamydia trachomatis / Q000378:metabolism; D016993:Chlamydophila pneumoniae / Q000378:metabolism*; D005634:Fructose-Bisphosphate Aldolase / Q000378:metabolism*; D006019:Glycolysis / Q000502:physiology; D006801:Humans
chemical_list: D001425:Bacterial Outer Membrane Proteins; D005634:Fructose-Bisphosphate Aldolase