Assembly and Function of a Spore Coat-Associated Transglutaminase of <i>Bacillus subtilis</i>

DOI Web Site 2 Citations
  • Rita Zilhão
    Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras Codex, Portugal
  • Rachele Isticato
    Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras Codex, Portugal
  • Lígia O. Martins
    Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras Codex, Portugal
  • Leif Steil
    Ernst-Moritz-Arndt-University, Medical Faculty, Laboratory for Functional Genomics, D-17487 Greifswald, Germany
  • Uwe Völker
    Ernst-Moritz-Arndt-University, Medical Faculty, Laboratory for Functional Genomics, D-17487 Greifswald, Germany
  • Ezio Ricca
    Dipartimento di Fisiologia Generale ed Ambientale, Università Federico II, Napoli, Italy
  • Charles P. Moran
    Emory University School of Medicine, Department of Microbiology and Immunology, Atlanta, Georgia 30322
  • Adriano O. Henriques
    Instituto de Tecnologia Química e Biológica, Universidade Nova de Lisboa, Avenida da República, Apartado 127, 2781-901 Oeiras Codex, Portugal

Abstract

<jats:title>ABSTRACT</jats:title> <jats:p> The assembly of a multiprotein coat around the <jats:italic>Bacillus subtilis</jats:italic> spore confers resistance to lytic enzymes and noxious chemicals and ensures normal germination. Part of the coat is cross-linked and resistant to solubilization. The coat contains ε-(γ-glutamyl)lysyl cross-links, and the expression of the gene ( <jats:italic>tgl</jats:italic> ) for a spore-associated transglutaminase was shown before to be required for the cross-linking of coat protein GerQ. Here, we have investigated the assembly and function of Tgl. We found that Tgl associates, albeit at somewhat reduced levels, with the coats of mutants that are unable to assemble the outer coat ( <jats:italic>cotE</jats:italic> ), that are missing the inner coat and with a greatly altered outer coat ( <jats:italic>gerE</jats:italic> ), or that are lacking discernible inner and outer coat structures ( <jats:italic>cotE gerE</jats:italic> double mutant). This suggests that Tgl is present at various levels within the coat lattice. The assembly of Tgl occurs independently of its own activity, as a single amino acid substitution of a cysteine to an alanine (C116A) at the active site of Tgl does not affect its accumulation or assembly. However, like a <jats:italic>tgl</jats:italic> insertional mutation, the <jats:italic>tglC116A</jats:italic> allele causes increased extractability of polypeptides of about 40, 28, and 16 kDa in addition to GerQ (20 kDa) and affects the structural integrity of the coat. We show that most Tgl is assembled onto the spore surface soon after its synthesis in the mother cell under σ <jats:sup>K</jats:sup> control but that the complete insolubilization of at least two of the Tgl-controlled polypeptides occurs several hours later. We also show that a multicopy allele of <jats:italic>tgl</jats:italic> causes increased assembly of Tgl and affects the assembly, structure, and functional properties of the coat. </jats:p>

Journal

  • Journal of Bacteriology

    Journal of Bacteriology 187 (22), 7753-7764, 2005-11-15

    American Society for Microbiology

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