IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...
IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...
IN INOCULANTS Nodulaid - 17th International Nitrogen Fixation ...
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17 th <strong>International</strong> Congress on <strong>Nitrogen</strong> <strong>Fixation</strong><br />
Fremantle, Western Australia<br />
27 November – 1 December 2011<br />
Title Functional characterization and interactions of the azorhizobial parA and parB proteins<br />
Author Min-Hua Peng 1 , Yu-Sheng Wang 1 , Ming-Yen Tsai 2 , Hisao-Lin Chien 2 , Kung-Ta Lee 1 ,<br />
Poster Board Number 46<br />
Chi-Te Liu 2,3, *<br />
1 Department of Biochemical Science and Technology, National Taiwan University, Taipei<br />
106, Taiwan<br />
2 Institute of Biotechnology, National Taiwan University, Taipei, 106, Taiwan<br />
3 Agricultural Biotechnology Research Centre, Academia Sinica, Taipei, 115, Taiwan<br />
Bacteroid development consists of several stages, and a number of bacterial genes that are involved in this<br />
process have been identified. However, the genes and factors that are engaged in the initiation of bacteroid<br />
formation, and those that regulate it, are incompletely identified. Our experimental evidence has demonstrated<br />
that the chromosome-partitioning gene (parA) gene of Azorhizobium caulinodans ORS571 not only plays crucial<br />
roles in cellular development when the microbe is free-living but also negatively regulates bacteroid formation in<br />
Sesbania rostrata stem nodules. In this study, we will clarify the functions of the recombinant ParA and ParB<br />
proteins of A. caulinodans, and the interactions between the par system and bacteroid differentiation related<br />
genes. We noticed that the ATPase activity of ParA can be enhanced in the presence of ParB protein. In<br />
addition, ParB bound to a centromere-like parS DNA fragment, and was stimulated by the increasing amounts of<br />
ParA protein. Interactions between ParA and ParB were confirmed by in vitro immunoprecipitation assay. Using<br />
gel mobility shift assay, we found that ParB bound to the bacteroid formation associative gene (bacA) and the<br />
promoter region of par operon. This binding seems to be regulated by mole ratio of ParB/ ParA . We proposed a<br />
mechanism for regulation of bacteroid differentiation of A. caulinodans. Interactions between azorhizobial ParA<br />
and ParB proteins may function as a checkpoint, which couples the chromosome partitioning to the onset of<br />
bacteroid formation in symbiosis.<br />
Liu, C.-T., Lee, K.-B., Wang, Y.-S., Peng, M.-H., Lee, K.-T., Suzuki, S., Suzuki, T. & Oyaizu, H. (2011).<br />
Involvement of the azorhizobial chromosome partition gene (parA) in the onset of bacteroid differentiation during<br />
Sesbania rostrata stem nodule development. Appl Environ Microbiol 77, 4371-4382.<br />
161<br />
2011