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Microbial Development

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Bacterial spores are encased in a protein shield (or coat) that confers resistance against noxious chemicals and predation, protects the underlying cortex peptidoglycan layer from the action of lytic enzymes, and is a key sensor of the environment. The spore surface proteins are synthesized in the mother cell, one of the two compartments of the sporulating cell.
 

 


Adriano O. Henriques
Professor Associado
PhD 1993 in Cell Biology, Universidade de Coimbra, Portugal

Phone (+351) 214469521 | Extension 1521
aoh@itqb.unl.pt

 

Research Interests

Bacterial spores are encased in a protein shield (or coat) that confers resistance against noxious chemicals and predation, protects the underlying cortex peptidoglycan layer from the action of lytic enzymes, and is a key sensor of the environment. The spore surface proteins are synthesized in the mother cell, one of the two compartments of the sporulating cell.

Bacterial spores rely on morphogenetic proteins such as SpoVID and SafA for their targeting to the surface of the developing spore. In the absence of SpoVID, for instance, the surface proteins are misassembled as swirls throughout the mother cell cytoplasm, and the resulting spores, with an exposed cortex, are susceptible to lysozyme. Both SpoVID and SafA, orthologs of which are found in all Bacillus species, have LysM domains for peptidoglycan binding and localize to the cortex-coat interface. We have shown that a 13 amino acid region (region A) just downstream of the N-terminal LysM domain of SafA, is critical for its interaction with SpoVID. Lesions in region  impair the interaction of SafA with SpoVID in vitro, and while not affecting the accumulation of SafA in vivo, interfere with the localization of SafA around the developing spore, causing aberrant assembly of the coat and lysozyme sensitivity. A peptide corresponding to region A interacts with SpoVID, showing that residues within this region directly contact SpoVID. Since region A is highly conserved among SafA orthologs, this motif is likely to be an important determinant of coat assembly in the Bacillus group of spore-formers. Our results show that the function of SafA relies on the ability of the protein to reach its fi nal cellular address trough a direct interaction with SpoVID. The localization of SpoVID in turn, relies on proper localization of another morphogenetic protein, SpoIVA, to the surface of the developing spore. Hence, the early stages in the attachment of the coat to the spore surface involve a cascade of protein-protein interactions among key morphogenetic proteins. These morphogenetic proteins have no counterparts in unrelated organisms and are likely to function in novel ways in the assembly of a multi-protein structure. Interference with their function will result in unstable spores, in what could be the basis for novel inactivation strategies of spores produced by pathogens such as B. cereus or B. anthracis.

 

Group Members

    • Mónica Serrano, Post-doc
    • Gonçalo Real, Post-doc
    • Anabela Isidro, Post-doc
    • Luísa Côrte, PhD student
    • Cláudia Serra, PhD student
    • Carla Esteves, Master Student
    • Pedro Rodrigues, Master Student
    • Catarina Fernandes, Undergraduate
    • Ana Almeida, Volunteer

 

Selected Publications

  1. Uyen, NQ, Tam, NMK, Hong, HA., Duc, LH, Hoa, TT, Serra, C, Henriques, AO, and Cutting, SM (2006) The intestinal life cycle of Bacillus subtilis and close relatives. Journal of Bacteriology 188(7): 2692-2700.
  2. Costa, T, Isidro, AL, Moran CP Jr., and Henriques, AO (2006) The interaction between coat morphogenetic proteins SafA and SpoVID. Journal of Bacteriology 188(22): 7731-7741.
  3. Thompson, LS, Beech, P, Real, G, Henriques, AO, and Harry, EJ (2006) A requirement for the cell division protein, DivIB, in polar cell division and engulfment during sporulation in Bacillus subtilis. Journal of Bacteriology 188(21):7677-7685.


Laboratory's Website

For further information visit the laboratory's website
 

Desenvolvimento Microbiano (PT)

Em condições nutricionais muito adversas, algumas bactérias iniciam um processo de diferenciação celular que resulta na produção de esporos. Os esporos são estruturas celulares metabolicamente adormecidas, capazes de resistir a condições extremas, incluindo ambientes extraterrestres simulados ou reais, que resultariam na destruição rápida das células originais. Acima de tudo, os esporos bacterianos resistem ao tempo podendo permanecer viáveis durante muitos milhões de anos. Representam assim um meio efi ciente de preservação do genoma, actuando como verdadeiras cápsulas do tempo. A nossa actividade centra-se no estudo dos mecanismos moleculares que controlam a metamorfose da célula bacteriana num esporo, incluindo a geração de assimetria e de informação posicional, a coordenação entre a expressão genética e o curso da morfogénese, e a montagem de estruturas supramoleculares. Utilizamos sobretudo o organismo modelo não patogénico Bacillus subtilis, para o qual existem ferramentas poderosas de análise genética. Alguns projectos do laboratório procuram tirar partido das propriedades únicas destes esporos para aplicações em biotecnologia  e em biomedicina. Outros projectos lidam com a identificação e a inactivação de esporos já que noutras espécies, por exemplo em B. cereus ou B. anthracis, estes são determinantes no estabelecimento  de doenças.

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