design and diversity in bacterial chemotaxis a comparative study in escherichia coli and bacillus subtilis设计和多样性细菌趋化性大肠杆菌和枯草芽孢杆菌的比较研究.pdfVIP

PLoS BIOLOGY Design and Diversity in Bacterial Chemotaxis: A Comparative Study in Escherichia coli and Bacillus subtilis 1 2 1,3* Christopher V. Rao , John R. Kirby , Adam P. Arkin 1 Department of Bioengineering, University of California, Berkeley, California, United States of America, 2 School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America, 3 Howard Hughes Medical Institute, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America Comparable processes in different species often involve homologous genes. One question is whether the network structure, in particular the feedback control structure, is also conserved. The bacterial chemotaxis pathways in E. coli and B. subtilis both regulate the same task, namely, excitation and adaptation to environmental signals. Both pathways employ many orthologous genes. Yet how these orthologs contribute to network function in each organism is different. To investigate this problem, we propose what is to our knowledge the first computational model for B. subtilis chemotaxis and compare it to previously published models for chemotaxis in E. coli. The models reveal that the core control strategy for signal processing is the same in both organisms, though in B. subtilis there are two additional feedback loops that provide an additional layer of regulation and robustness. Furthermore, the network structures are different despite the similarity of the proteins in each organism. These results demonstrate the limitations of pathway inferences based solely on homology and suggest that the control strategy is an evolutionarily conserved property. Introduction