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The Transmembrane Helix of the Escherichia coli Division Protein FtsI Localizes to the Septal Ring
Journal article   Open access   Peer reviewed

The Transmembrane Helix of the Escherichia coli Division Protein FtsI Localizes to the Septal Ring

Mark C Wissel, Jennifer L Wendt, Calista J Mitchell and David S Weiss
Journal of bacteriology, Vol.187(1), pp.320-328
01/2005
DOI: 10.1128/JB.187.1.320-328.2005
PMID: 15601716
url
https://doi.org/10.1128/JB.187.1.320-328.2005View
Published (Version of record) Open Access

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 usual 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.
Microbial Cell Biology

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