title: Mycobacterium bovis BCG cell wall and lipopolysaccharide induce a novel gene, BIGM103, encoding a 7-TM protein: identification of a new protein family having Zn-transporter and Zn-metalloprotease signatures.
abstract: To identify novel genes induced during innate immune activation, we screened a cDNA library prepared from monocytes stimulated with Mycobacterium bovis BCG cell wall. A novel transcript with three-protein coding potential was identified, and the expressed proteins from individual frames showed distinct intracellular localization. Live and heat-killed Mycobacterium, bacterial cell wall, and inflammatory cytokines like TNFalpha were found to be potent inducers of the transcript. Expression of this gene is very low or undetectable in unstimulated monocytes, while a steady expression level was observed during differentiation of monocytes to dendritic cells and macrophages. The entire gene consisted of eight major exons and was localized on chromosome 4q22-q24, spanning approximately 84 kb. The main open reading frame of the transcript encoded a putative seven-transmembrane (TM) protein that showed homology with a number of functionally unknown proteins in the database. Further analysis revealed that all of these proteins have detectable similarity with the ZIP family of metal transporters. In fact, increased accumulation of intracellular Zn(2+) was observed due to the expression of BIGM103 in CHO cells. However, the identified proteins are structurally unique compared to known ZIP members and they also possess the hallmark of Zn-metalloproteases, suggesting a new class of multi-TM protein with dual features. Here we present a collection of these proteins and discuss the functional aspects of BIGM103, based on our results and current findings on two members of the family, Drosophila Catsup and Arabidopsis IAR1.
authors.affiliation: Department of Immunology, Osaka Medical Center for Cancer and Cardiovascular Diseases, Higashinari-ku, Osaka, 537-8511, Japan.
authors.forename: Nasim A
authors.initials: NA
authors.lastname: Begum
authors.forename: Mika
authors.initials: M
authors.lastname: Kobayashi
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Moriwaki
authors.forename: Misako
authors.initials: M
authors.lastname: Matsumoto
authors.forename: Kumao
authors.initials: K
authors.lastname: Toyoshima
authors.forename: Tsukasa
authors.initials: T
authors.lastname: Seya
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015152:Blotting, Northern; D019556:COS Cells; D002352:Carrier Proteins / Q000235:genetics; D002460:Cell Line; D017358:Cell Wall Skeleton / Q000737:chemistry / Q000494:pharmacology*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D003713:Dendritic Cells / Q000187:drug effects / Q000378:metabolism; D005091:Exons; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D005796:Genes / Q000235:genetics; D049452:Green Fluorescent Proteins; D006367:HeLa Cells; D006801:Humans; D007438:Introns; D008070:Lipopolysaccharides / Q000494:pharmacology*; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D009000:Monocytes / Q000187:drug effects / Q000378:metabolism; D009163:Mycobacterium bovis / Q000737:chemistry*; D010802:Phylogeny; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014407:Tumor Cells, Cultured; D015032:Zinc / Q000737:chemistry / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D017358:Cell Wall Skeleton; D018076:DNA, Complementary; D008070:Lipopolysaccharides; D008164:Luminescent Proteins; D008565:Membrane Proteins; D011993:Recombinant Fusion Proteins; C017800:zinc-binding protein; D049452:Green Fluorescent Proteins; D008666:Metalloendopeptidases; D015032:Zinc