Lotte Søgaard-Andersen

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Max Planck Institute for Terrestrial Microbiology
Sogaard-Andersen, Lotte

Lotte Søgaard-Andersen obtained her M.D. and PhD in molecular biology from the University of Odense in Denmark. She moved to Marburg in 2004 as Director and Head of the Department of Ecophysiology at the Max Planck Institute for Terrestrial Microbiology.

Her research interests focuses on how bacterial cells process information to generate and regulate output responses such as adaptation, differentiation, growth and cell movement. Information processing is carried out by complex networks of signal transduction proteins. A challenging problem is to understand how these protein networks are organized in space and time to allow the ordered execution of these various tasks. We probe this question by studying signal transduction pathways and networks governing development, motility, cell polarity, and cell cycle in Myxococcus xanthus.

ABSTRACT: Defining a molecular module for regulation of dynamic cell polarity

All natural cells display regulated gene expression and are spatially highly organized. Major strides have been made in synthetic biology to design and engineer circuits that control gene expression. In comparison, the design and engineering of circuits for the spatial organization of cells remain a central challenge. This deficit is, at least in part, due to our poor understanding of the mechanisms responsible for spatially organizing cells. Bacterial cells display polarity with many proteins localizing asymmetrically to specific subcellular regions. Moreover, several of these proteins localize dynamically and change their localization over time. For most of these proteins, changes in localization are intimately tied in with cell cycle progression. A comparatively simpler case of bacterial cell polarity is represented by motility proteins in the rod-shaped cells of M. xanthus that localize dynamically to the cell poles in a cell cycle-independent manner, i.e. during a cellular reversal motility proteins localizing to the lagging cell pole switch to the new lagging cell pole and proteins at the old leading pole switch to the new leading cell pole. This system for cell cycle-independent regulation of dynamic cell polarity is built around the small GTPase MglA, which functions as a nucleotide-dependent molecular switch, and its cognate GAP MglB. MglA/GTP and MglB bind to the leading and lagging cell pole, respectively and define the leading/lagging polarity axis in M. xanthus. In response to signaling by the Frz chemosensory system, MglA/GTP and MglB switch poles resulting in an inversion of the polarity axis. We use this system to understand design rules for circuits regulating dynamic cell polarity. Our work to characterize the components of the system as well as our efforts to establish this system as a module for regulation of dynamic cell polarity in other bacteria will be presented.