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| Thursday, June 21, 2012
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Noon - 1:00 PM
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The ABCs of bacterial cell division
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| Description: |
Speaker: Thomas G. Bernhardt, Ph.D., Harvard Medical School
Location: The Forsyth Institute, Seminar Room A, 245 First Street, 17th Floor, Cambridge
Abstract: ABC transporters are ubiquitous membrane protein complexes that move substrates across membranes. They do so using ATP-induced conformational changes in their nucleotide binding domains (NBDs) to alter the conformation of the transport cavity formed by their transmembrane domains (TMDs). In Escherichia coli, an ABC transporter-like complex composed of FtsE (NBD) and FtsX (TMD) has long been known to be important for cytokinesis, but its role in the process has remained mysterious. Here I will present our identification of FtsEX as a regulator of cell wall hydrolysis at the division site. Cell wall material synthesized by the division machinery is initially shared by daughter cells and must be split by hydrolytic enzymes called amidases to drive daughter cell separation. We recently showed that the amidases require activation at the cytokinetic ring by proteins with LytM domains, of which EnvC is the most critical. I will show that the FtsEX directly recruits EnvC to the septum via an interaction between EnvC and a periplasmic loop of FtsX. Importantly, I will also show that FtsEX variants predicted to be ATPase defective still recruit EnvC to the septum but fail to promote cell separation. Our results thus suggest the attractive possibility that amidase activation via EnvC in the periplasm is regulated by conformational changes in the FtsEX complex mediated by ATP hydrolysis in the cytoplasm. Since FtsE has been reported to interact with the tubulin-like FtsZ protein, this provides a potential mechanism for coupling amidase activity with the contraction of the FtsZ cytoskeletal ring.
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| Contact: |
Pam Quattrocchi
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Week of Sunday, June 17, 2012
