A protein secretion portal at the hyphal tips of Streptomyces coelicolor?

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Some bacterial proteins operate on the outside of the cell, for example the toxins produced by bacterial pathogens. Since all proteins are made inside the bacterium the extracellular proteins must be moved out of the cell across the normally impermeable cell membrane. This task is carried out by machines termed protein transporters that are located in the cell membrane. One type of transporter moves unfolded proteins, threading them across the membrane like string through the eye of a needle. By contrast, a second type of transporter, which we term the Tat system, moves folded proteins across the membrane. We want to study the Tat transporter in a bacterium called Streptomyces coelicolor. S. coelicolor is an organism that lives in the soil. It lives on dead plant and animal material and to break this material down it needs to export lots of proteins through the Tat transporter. S. coelicolor has a complex lifecycle because it germinates from a spore which grows into structures called hyphae. These hyphae can be thought of as long tubes, and we have shown that the Tat transporter is located at the very tip of these tubes. We have shown this by adding a label to one of the proteins involved in the Tat pathway which makes it appear as coloured spot when viewed in a special type of microscope. In this project we want to understand why and how the Tat transporter is located here. Some of the experiments we will do will find out whether other transporters are also located at the tips of these hyphae by labeling them in a similar way. We want to find mutants of S. coelicolor where the Tat transporter is no longer located in its normal place. We can use these mutants to give us information about the processes that help to locate the Tat transporter at the correct place in the cell.