title: Proteome analysis of excretory-secretory proteins ofEntamoeba histolyticaHM1:IMSS via LC-ESI-MS/MS and LC-MALDI-TOF/TOF.
abstract: BACKGROUND
  Excretory-secretory (ES) proteins ofE. histolyticaare thought to play important roles in the host invasion, metabolism, and defence. Elucidation of the types and functions ofE. histolyticaES proteins can further our understanding of the disease pathogenesis. Thus, the aim of this study is to use proteomics approach to better understand the complex ES proteins of the protozoa.
  
  
  METHODS
  E. histolyticaES proteins were prepared by culturing the trophozoites in protein-free medium. The ES proteins were identified using two mass spectrometry tools, namely, LC-ESI-MS/MS and LC-MALDI-TOF/TOF. The identified proteins were then classified according to their biological processes, molecular functions, and cellular components using the Panther classification system (PantherDB).
  
  
  RESULTS
  A complementary list of 219 proteins was identified; this comprised 201 proteins detected by LC-ESI-MS/MS and 107 proteins by LC-MALDI-TOF/TOF. Of the 219 proteins, 89 were identified by both mass-spectrometry systems, while 112 and 18 proteins were detected exclusively by LC-ESI-MS/MS and LC-MALDI-TOF/TOF respectively. Biological protein functional analysis using PantherDB showed that 27% of the proteins were involved in metabolic processes. Using molecular functional and cellular component analyses, 35% of the proteins were found to be involved in catalytic activity, and 21% were associated with the cell parts.
  
  
  CONCLUSIONS
  This study showed that complementary use of LC-ESI-MS/MS and LC-MALDI-TOF/TOF has improved the identification of ES proteins. The results have increased our understanding of the types of proteins excreted/secreted by the amoeba and provided further evidence of the involvement of ES proteins in intestinal colonisation and evasion of the host immune system, as well as in encystation and excystation of the parasite.
authors.affiliation: Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia.
authors.forename: Jorim Anak
authors.initials: JA
authors.lastname: Ujang
authors.affiliation: Analytical Biochemistry Research Centre, Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia.
authors.forename: Soon Hong
authors.initials: SH
authors.lastname: Kwan
authors.affiliation: Analytical Biochemistry Research Centre, Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia.
authors.forename: Mohd Nazri
authors.initials: MN
authors.lastname: Ismail
authors.affiliation: School of Health Sciences, Universiti Sains Malaysia, 16150 Kubang Kerian, Kelantan Malaysia.
authors.forename: Boon Huat
authors.initials: BH
authors.lastname: Lim
authors.affiliation: Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia.
authors.forename: Rahmah
authors.initials: R
authors.lastname: Noordin
authors.affiliation: Institute for Research in Molecular Medicine (INFORMM), Universiti Sains Malaysia, 11800 Gelugor, Penang Malaysia.
authors.forename: Nurulhasanah
authors.initials: N
authors.lastname: Othman
keywords: Entamoeba histolytica; Excretory-secretory (ES) proteins; LC–ESI–MS/MS; LC–MALDI–TOF/TOF