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Characterizing proteases in an Antarctic Janthinobacterium sp. isolate: Evidence of a protease horizontal gene transfer event

Cecilia Martinez-Rosales1,2☆, Juan José Marizcurrena1☆, Andrés Iriarte3,4,5☆,Natalia Fullana1, Héctor Musto5 & Susana Castro-Sowinski1,2*   

  1. 1 Sección Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de la República (UdelaR), Igua 4225, 11400, Montevideo, Uruguay;
    2 Microbiología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE). Av Italia 3318, 11600, Montevideo, Uruguay;
    3 Dpto de Bioquímica y Genómica Microbiana and Dpto de Genómica (IIBCE);
    4 Dpto de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, UdelaR;
    5 Laboratorio de Organización y Evolución del Genoma, Facultad de Ciencias, UdelaR
  • 出版日期:1965-03-30 发布日期:1965-03-30
  • 通讯作者: Susana Castro-Sowinski

Characterizing proteases in an Antarctic Janthinobacterium sp. isolate: Evidence of a protease horizontal gene transfer event

Cecilia Martinez-Rosales1,2☆, Juan José Marizcurrena1☆, Andrés Iriarte3,4,5☆,Natalia Fullana1, Héctor Musto5 & Susana Castro-Sowinski1,2*   

  1. 1 Sección Bioquímica y Biología Molecular, Facultad de Ciencias, Universidad de la República (UdelaR), Igua 4225, 11400, Montevideo, Uruguay;
    2 Microbiología Molecular, Instituto de Investigaciones Biológicas Clemente Estable (IIBCE). Av Italia 3318, 11600, Montevideo, Uruguay;
    3 Dpto de Bioquímica y Genómica Microbiana and Dpto de Genómica (IIBCE);
    4 Dpto de Desarrollo Biotecnológico, Instituto de Higiene, Facultad de Medicina, UdelaR;
    5 Laboratorio de Organización y Evolución del Genoma, Facultad de Ciencias, UdelaR
  • Online:1965-03-30 Published:1965-03-30
  • Contact: Susana Castro-Sowinski

摘要: We report the isolation of a cold-adapted bacterium belonging to the genus Janthinobacterium (named AU11), from a water sample collected in Lake Uruguay (King George Island, South Shetlands). AU11 (growth between 4°C and 30°C) produces a single cold-active extracellular protease (ExPAU11), differentially expressed at low temperature. ExPAU11 was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) as an alkaline metallo-protease (70% coverage with an extracellular protease of Janthinobacterium sp. PI12), and by protease-inhibitor screening identified as a serine-protease. To the best of our knowledge this is the first experimental evidence of a cold-active extracellular protease produced by Janthinobacterium. Furthermore, we identified a serine-protease gene (named JSP8A) showing 60% identity (98% query coverage) to subtilisin peptidases belonging to the S8 family (S8A subfamily) of many cyanobacteria. A phylogenetic analysis of the JSP8A protease, along with related bacterial protein sequences, confirms that JSP8A clusters with S8A subtilisin sequences from different cyanobacteria, and is clearly separated from S8A bacterial sequences of other phyla (including its own). An analysis of the genomic organization around JSP8A suggests that this protease gene was acquired in an event that duplicated a racemase gene involved in transforming L- to D-amino acids. Our results suggest that AU11 probably acquired this subtilisin-like protease gene by horizontal gene transfer (HGT) from a cyanobacterium. We discuss the relevance of a bacterial protease-HGT in the Antarctic environment in light of this hypothesis.

关键词: Antarctic, cold-active protease, horizontal gene transfer, Janthinobacterium, subtilisin

Abstract: We report the isolation of a cold-adapted bacterium belonging to the genus Janthinobacterium (named AU11), from a water sample collected in Lake Uruguay (King George Island, South Shetlands). AU11 (growth between 4°C and 30°C) produces a single cold-active extracellular protease (ExPAU11), differentially expressed at low temperature. ExPAU11 was identified by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToF MS) as an alkaline metallo-protease (70% coverage with an extracellular protease of Janthinobacterium sp. PI12), and by protease-inhibitor screening identified as a serine-protease. To the best of our knowledge this is the first experimental evidence of a cold-active extracellular protease produced by Janthinobacterium. Furthermore, we identified a serine-protease gene (named JSP8A) showing 60% identity (98% query coverage) to subtilisin peptidases belonging to the S8 family (S8A subfamily) of many cyanobacteria. A phylogenetic analysis of the JSP8A protease, along with related bacterial protein sequences, confirms that JSP8A clusters with S8A subtilisin sequences from different cyanobacteria, and is clearly separated from S8A bacterial sequences of other phyla (including its own). An analysis of the genomic organization around JSP8A suggests that this protease gene was acquired in an event that duplicated a racemase gene involved in transforming L- to D-amino acids. Our results suggest that AU11 probably acquired this subtilisin-like protease gene by horizontal gene transfer (HGT) from a cyanobacterium. We discuss the relevance of a bacterial protease-HGT in the Antarctic environment in light of this hypothesis.

Key words: Antarctic, cold-active protease, horizontal gene transfer, Janthinobacterium, subtilisin