成功测序肉毒杆菌基因组

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成功测序肉毒杆菌基因组 英国诺丁汉大学科学家在最新一期《基因组研究》杂志上发表报告说，他们成功地对肉毒杆菌的基因组进行了测序。肉毒杆菌可产生致命毒素，因此破译它的基因组将有助于更好地了解和利用这种特殊细菌。
英国诺丁汉大学科学家在最新一期《基因组研究》杂志上发表报告说，他们成功地对肉毒杆菌的基因组进行了测序。肉毒杆菌可产生致命毒素，因此破译它的基因组将有助于更好地了解和利用这种特殊细菌。  

  据美国科学促进会网站２５日报道，诺丁汉大学的基因组测序小组介绍，通常情况下，肉毒杆菌都处于休眠孢子状态，或者在土壤里的动物腐尸中“谋生”。它会伺机而动，通过受污染的食物或外部伤口，进入活体动物体内，引发宿主中毒甚至致命。  

   研究小组说，肉毒杆菌的独特之处就在于，在环境不宜时它可以处于冬眠状态“休养生息”，一旦成功进入活体动物体内，肉毒杆菌立即激活，猛烈攻击宿主。攻下一个宿主之后，肉毒杆菌便以此为新的冬眠环境，耐心等待下一次机会。研究人员称，肉毒杆菌的这种生存机制与大多数细菌迥然不同，“是另一种极端的机会主义生存方式”。  

  肉毒杆菌的基因组十分稳定，属“梭状芽孢杆菌属”。与“梭状芽孢杆菌属”其他５种已破译基因组的细菌相比，肉毒杆菌仅有１６％的基因是与其他５种共有的，而４３％的基因都是肉毒杆菌所特有的。  

  肉毒杆菌本身通常又可细分为几个不同变种，但实际上肉毒杆菌不同变种之间的差异也颇大，唯一的共性就是它们都能分泌致命毒素。这种毒素可以破坏神经功能，因此在医学领域用于治疗眼睑及面肌痉挛，美容领域还用它来除皱。

原始出处:

Published online before print May 22, 2007
Genome Research, DOI: 10.1101/gr.6282807
Letter

Genome sequence of a proteolytic (Group I) Clostridium botulinum strain Hall A and comparative analysis of the clostridial genomes
Mohammed Sebaihia1, Michael W. Peck2, Nigel P. Minton3, Nicholas R. Thomson1, Matthew T.G. Holden1, Wilfrid J. Mitchell4, Andrew T. Carter2, Stephen D. Bentley1, David R. Mason2, Lisa Crossman1, Catherine J. Paul5, Alasdair Ivens1, Marjon H.J. Wells-Bennik2, Ian J. Davis3, Ana M. Cerde駉-Tárraga1, Carol Churcher1, Michael A. Quail1, Tracey Chillingworth1, Theresa Feltwell1, Audrey Fraser1, Ian Goodhead1, Zahra Hance1, Kay Jagels1, Natasha Larke1, Mark Maddison1, Sharon Moule1, Karen Mungall1, Halina Norbertczak1, Ester Rabbinowitsch1, Mandy Sanders1, Mark Simmonds1, Brian White1, Sally Whithead1, and Julian Parkhill1,6

1 Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA, United Kingdom; 2 Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, United Kingdom; 3 Centre for Biomolecular Sciences, Institute of Infection, Immunity and Inflammation, School of Molecular Medical Sciences, University of Nottingham, Nottingham NG7 2RD, United Kingdom; 4 School of Life Sciences, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, United Kingdom; 5 Bureau of Microbial Hazards, Health Canada, Ottawa, Ontario, K1A 0L2, Canada

Abstract

Clostridium botulinum is a heterogeneous Gram-positive species that comprises four genetically and physiologically distinct groups of bacteria that share the ability to produce botulinum neurotoxin, the most poisonous toxin known to man, and the causative agent of botulism, a severe disease of humans and animals. We report here the complete genome sequence of a representative of Group I (proteolytic) C. botulinum (strain Hall A, ATCC 3502). The genome consists of a chromosome (3,886,916 bp) and a plasmid (16,344 bp), which carry 3650 and 19 predicted genes, respectively. Consistent with the proteolytic phenotype of this strain, the genome harbors a large number of genes encoding secreted proteases and enzymes involved in uptake and metabolism of amino acids. The genome also reveals a hitherto unknown ability of C. botulinum to degrade chitin. There is a significant lack of recently acquired DNA, indicating a stable genomic content, in strong contrast to the fluid genome of Clostridium difficile, which can form longer-term relationships with its host. Overall, the genome indicates that C. botulinum is adapted to a saprophytic lifestyle both in soil and aquatic environments. This pathogen relies on its toxin to rapidly kill a wide range of prey species, and to gain access to nutrient sources, it releases a large number of extracellular enzymes to soften and destroy rotting or decayed tissues

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