International Journal of the Physical Sciences Vol. 6(15), pp. 3733-3744, 4 August, 2011 Available online at http://www.academicjournals.org/IJPS DOI: 10.5897/IJPS10.250 ISSN 1992 - 1950 ©2011 Academic Journals Full Length Research Paper Spatial distributions and energy landscape of MinE protein dynamics via the biophysical spot tracking technique Sitta Aroonnual 1 , Waipot Ngamsaad 1,7 , Paisan Kanthang 1,2 , Narin Nuttawut 1,6 , Wannapong Triampo 1,4,6 *, Darapond Triampo 3,6 and Chartchai Krittanai 5 1 R&D Group of Biological and Environmental Physics, Department of Physics, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. 2 Rajamangala University of Technology, Phra Nakhon, Bangkok 10800, Thailand. 3 Department of Chemistry, Center of Excellence for Innovation in Chemistry, Faculty of Science, Mahidol University, Bangkok 10400, Thailand. 4 Institute for Innovative Learning, Mahidol University, 999, Phuttamonthon 4 Road, Salaya, Nakorn Pathom 73170, Thailand. 5 Institute of Molecular Biosciences, Mahidol University, Salaya Campus, Nakhon Pathom, Thailand. 6 ThEP Center, CHE, 328 Si Ayutthaya Road, Bangkok, 10400 Thailand. 7 School of Science, University of Phayao, Phayao 56000, Thailand. Accepted 2 June, 2011 The MinCDE protein system is known to dictate cytokinesis cell division in prokaryotes by spatial regulation of the Z-ring. The oscillatory dynamics of MinC and MinD depends on the presence of MinE, where the MinE protein dynamics acts as a topological specificity to the midcell. In this work, the Spot Tracking Technique is used to determine the biophysical quantities of MinE protein dynamics, namely, diffusive motion, velocity distribution, spatial distribution, and energy profile. An alternative quantity that indicates the potential of the mean force characteristic function is proposed to be an effective potential parameter to indicate the optimal energy to generate a stable spatial-temporal pattern formation of MinE proteins. The localization and distribution patterns along the cell length were well confirmed, while other quantitative information related to MinE cluster positions have been revealed. In addition, the effective potential was found to relate to the spring-like potential. The minimum region indicates the potential cluster depth that occurs near the midcell zone, which corresponds to the finding that the MinE cluster is mostly concentrated at midcell. Key words: Spot tracking technique, cell division, MinE proteins, protein oscillation. INTRODUCTION Cytokinesis in prokaryotes needs to be spatially regulated in order to ensure that it occurs between daughter genomes. In Escherichia coli (E. coli) and other rod-shaped bacteria, cytokkinesis is initiated by the tubulin-like GTP *Corresponding author. E-mail: scwtr@mahidol.ac.th, wtriampo@gmail.com. Tel: 662 441-9816 ext. 1131. Fax: 662 441-9322. FtsZ in a polymeric ring at center of the cell that is called Z-ring (Lutkenhaus and Addinall, 1997; Rothfield et al., 1999). The midcell positioning of Z-ring is controlled by two major negative regulatory systems. The first system is called nucleoid occlusion, blocks Z-ring assembly in the cellular space that is occupied by nucleoid mass (Woldringh et al., 1991; Yu and Margolin, 1999). The other system consists of three proteins, MinC, MinD, and MinE, which prevent Z-ring assembly at the cell poles (de Boer et al., 1989; Rothfield et al., 2001).