Team:ETHZ Basel/Biology

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• Introduction
• Biology & Wet Laboratory
• Mathematical Modeling
• Information Processing
• Achievements
• Team

• Overview
• Molecular Mechanism
• Archeal Light Receptor
• Cloning Strategy
• Implementation
• Safety

Biology & Wet Laboratory Overview

Molecular mechanism of E. lemming. A light-sensitive dimerizing complex fused to proteins of the chemotaxis pathway at a spatially fixed location is induced by light pulses and therefore localization of the two molecules can be manipulated.

The core element of E. lemming is spatial localization of certain elements of the chemotactic network (Che proteins) and thus affecting the activity of their downstream partners. This anchoring is achieved with the help of light-sensitive proteins LSP's that dimerize upon a light signal. Dimerization results in spatial relocalization of the Che-protein and therefore altering the ratio between tumbling and directed flagellar movement.

Inside the cell, the chemotactic proteins CheA, CheY and CheZ tend to co-localize with methyl accepting chemotaxis protein MCPs at the membrane. But whereas CheA and CheZ nearly only localize at the MCPs, CheY is also present in significant concentrations in the cytoplasm making it's localization more straightforward [1].

For spatial localization of the Che-protein complex, three different anchor-proteins have been investigated:

1. The tetracyclin repressor tetR anchoring the Che-protein to the DNA by binding to it's operator site tetO that has been inserted into a plasmid [2].
2. The triggor factor TrigA binding to the large ribosomal subunit [3].
3. The prokaryotic actin homologue MreB which assembles into helical filaments underneath the cytoplasmic membrane [4].

These anchors should enable to control the tumbling frequency by localizing a Che-protein and therefore interfering with its activity.