title: A novel Mitosomal β-barrel Outer Membrane Protein in Entamoeba.
abstract: Entamoeba possesses a highly divergent mitochondrion-related organelle known as the mitosome. Here, we report the discovery of a novel protein in Entamoeba, which we name Mitosomal β-barrel Outer Membrane Protein of 30 kDa (MBOMP30). Initially identified through in silico analysis, we experimentally confirmed that MBOMP30 is indeed a β-barrel protein. Circular dichroism analysis showed MBOMP30 has a predominant β-sheet structure. Localization to Entamoeba histolytica mitosomes was observed through Percoll-gradient fractionation and immunofluorescence assay. Mitosomal membrane integration was demonstrated by carbonate fractionation, proteinase K digestion, and immunoelectron microscopy. Interestingly, the deletion of the putative β-signal, a sequence believed to guide β-barrel outer membrane protein (BOMP) assembly, did not affect membrane integration, but abolished the formation of a ~240 kDa complex. MBOMP30 represents only the seventh subclass of eukaryotic BOMPs discovered to date and lacks detectable homologs outside Entamoeba, suggesting that it may be unique to Entamoeba mitosomes.
authors.affiliation: 1] Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan [2] Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan [3] Institute of Biology, College of Science, University of the Philippines Diliman, Quezon City, 1101 Philippines.
authors.forename: Herbert J
authors.initials: HJ
authors.lastname: Santos
authors.affiliation: Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Imai
authors.affiliation: Department of Infectious Diseases, Tokai University School of Medicine, Isehara, Kanagawa 259-1193, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Makiuchi
authors.affiliation: Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Tomii
authors.affiliation: Computational Biology Research Center (CBRC), National Institute of Advanced Industrial Science and Technology (AIST), 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.
authors.forename: Paul
authors.initials: P
authors.lastname: Horton
authors.affiliation: Proteo-Science Center, Ehime University, 3 Bunkyo-cho, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Nozawa
authors.affiliation: Botany Department, Faculty of Science, Ain Shams University, Khalifa El-Maamon St, Abbasiya Sq., Cairo, 11566, Egypt.
authors.forename: Mohamed
authors.initials: M
authors.lastname: Ibrahim
authors.affiliation: Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Sakura-ku, Saitama, Saitama 338-8570, Japan.
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Tozawa
authors.affiliation: 1] Department of Parasitology, National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjuku-ku, Tokyo 162-8640, Japan [2] Graduate School of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki 305-8572, Japan.
authors.forename: Tomoyoshi
authors.initials: T
authors.lastname: Nozaki
mesh_terms: D000595:Amino Acid Sequence; D002942:Circular Dichroism; D004748:Entamoeba histolytica / Q000378:metabolism*; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D016253:Microscopy, Immunoelectron; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D013056:Spectrophotometry, Ultraviolet
chemical_list: D008565:Membrane Proteins