一组由美国、韩国和法国的科学家组成的研究小组最近完成了对两种实验室常用的大肠杆菌(E. coli)菌株基因组的测序工作。这项研究发表在10月17日Journal of Molecular Biology杂志上。
E. coli常与一些食源性疾病有关，但从人体肠道内分离出来的两种命名为K-12和B的良性大肠杆菌菌株却是两种重要实验用菌株。大肠杆菌K-12的基因组的测序工作已于1997年完成。而大肠杆菌B菌株自1918年被分离出来后，在1959年被分离为两类实验用菌株：一类REL606用于研究长期计划作用；另一类BL21(DE3)在医学和工业上用于生产蛋白质。因此，对这两类B菌株的测序工作直到最近才完成。
通过序列比较，研究人员发现，K-12和B这两种菌株基因序列的单个碱基对差异是非随机分布的。此外，通过对比两种不同的B菌株也发现了二者存在差异。（生物谷Bioon.com）
生物谷推荐原始出处：
Journal of Molecular Biology doi:10.1016/j.jmb.2009.09.052
Genome Sequences of Escherichia coli B strains REL606 and BL21(DE3)
Haeyoung Jeong1, Valérie Barbe2, Choong Hoon Lee1, 3, David Vallenet2, Dong Su Yu1, Sang-Haeng Choi1, Arnaud Couloux2, Seung-Won Lee1, Sung Ho Yoon1, Laurence Cattolico2, Cheol-Goo Hur1, 4, Hong-Seog Park1, 4, Béatrice Ségurens2, Sun Chang Kim3, Tae Kwang Oh1, 5, Richard E. Lenski6, F. William Studier7, , , Patrick Daegelen2, 8, , and Jihyun F. Kim1, 4, ,
1Korea Research Institute of Bioscience and Biotechnology (KRIBB), 111 Gwahangno, Yuseong, Daejeon 305-806, Korea
2CNRS UMR 8030, Genoscope (CEA), 2 rue Gaston Crémieux, CP 5706, 91000 Evry Cedex, France
3Department of Biological Sciences, Korea Advanced Institute of Science and Technology, Daejeon 305-701, Korea
4Functional Genomics Program, University of Science and Technology, Yuseong, Daejeon 305-333, Korea
521C Frontier Microbial Genomics and Applications Center, Yuseong, Daejeon 305-806, Korea
6Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI 48824, USA
7Biology Department, Brookhaven National Laboratory, P.O. Box 5000, Upton, NY 11973-5000, USA
8Inserm, 101 rue de Tolbiac, 75013 Paris, France
Escherichia coli K-12 and B have been the subjects of classical experiments from which much of our understanding of molecular genetics has emerged. We present here complete genome sequences of two E. coli B strains, REL606, used in a long-term evolution experiment, and BL21(DE3), widely used to express recombinant proteins. The two genomes differ in length by 72,304 bp and have 426 single base pair differences, a seemingly large difference for laboratory strains having a common ancestor within the last 67 years. Transpositions by IS1 and IS150 have occurred in both lineages. Integration of the DE3 prophage in BL21(DE3) apparently displaced a defective prophage in the λ attachment site of B. As might have been anticipated from the many genetic and biochemical experiments comparing B and K-12 over the years, the B genomes are similar in size and organization to the genome of E. coli K-12 MG1655 and have > 99% sequence identity over 92% of their genomes. E. coli B and K-12 differ considerably in distribution of IS elements and in location and composition of larger mobile elements. An unexpected difference is the absence of a large cluster of flagella genes in B, due to a 41 kbp IS1-mediated deletion. Gene clusters that specify the LPS core, O antigen, and restriction enzymes differ substantially, presumably because of horizontal transfer. Comparative analysis of 32 independently isolated E. coli and Shigella genomes, both commensals and pathogenic strains, identifies a minimal set of genes in common plus many strain-specific genes that constitute a large E. coli pan-genome.
