The transmembrane helix of the Escherichia coli division protein FtsI localizes to the septal ring.
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Wissel MC, Wendt JL, Mitchell CJ, Weiss DS
The transmembrane helix of the Escherichia coli division protein FtsI localizes to the septal ring.
J Bacteriol. 2005 Jan;187(1):320-8.
- PubMed ID
- 15601716 [ View in PubMed]
- Abstract
FtsI (also called PBP3) of Escherichia coli is a transpeptidase required for synthesis of peptidoglycan in the division septum and is one of about a dozen division proteins that localize to the septal ring. FtsI comprises a short amino-terminal cytoplasmic domain, a single transmembrane helix (TMH), and a large periplasmic domain that encodes the catalytic (transpeptidase) activity. We show here that a 26-amino-acid fragment of FtsI is sufficient to direct green fluorescent protein to the septal ring in cells depleted of wild-type FtsI. This fragment extends from W22 to V47 and corresponds to the TMH. This is a remarkable finding because it is unusual [corrected] for a TMH to target a protein to a site more specific than the membrane. Alanine-scanning mutagenesis of the TMH identified several residues important for septal localization. These residues cluster on one side of an alpha-helix, which we propose interacts directly with another division protein to recruit FtsI to the septal ring.