A synthetic multicellular system for programmed pattern formation
(Mitja Crček)
A synthetic multicellular system for programmed pattern formation
Subhayu Basu, Yoram Gerchman, Cynthia H. Collins, Frances H. Arnold & Ron Weiss
Nature 434, 1130-1134 (28 April 2005)
INTRODUCTION
Pattern formation is a frequently observed behavior in the living world. Many years ago scientists started to examine a pattern formation in prokaryotes and later also in eukaryotes. Here we focus on bacterial patterns because their formation has lower complexity and is therefore easier to understand. Microbiologists found that in nature, bacteria have to deal with many different environmental conditions. To increase the viability of the single bacteria, bacterial colonies are formed. To do that, bacteria had to develop complex communication pathways. Those networks are nowadays well studied and therefore synthetic biologists could start researching synthetic multicellular systems for programmed pattern formation.
Here we first explain the basics of cell-cell communication using acyl-homoserine lactone (AHL) as signal molecule so the pattern formation process will be easier to understand. We describe Tet regulatory system, lux operon, lac operon and Lac repressor to explain the molecular basis and show the role of AHL.
In the second section we explain how the signaling process works in engineering cells and how the output protein is produced. We describe the molecular network in sender cells and receiver cells. The correlation between various AHL concentrations (high, medium or low) and output protein production (e.g. GFP) is shown as well as the role of repressors and activators. We show why only the receiver cells that are at appropriate distances from the sender cells can express GFP.
In the third part we focus on pattern formation. We first describe the construction of plasmids for sender and for receiver cells. We explain how bacterial strains for experiments were prepared and show simulations and experimental result of their GFP production. Illustrated with photographs we describe circular pattern formation and explain why the system works like that. Last but not least we describe the basics of ring formation dynamics and show the design of other patterns.
