Role of Leucine Zipper Motifs in Association of the Escherichia coli Cell Division Proteins FtsL and FtsB

Institut Pasteur, CNRS URA 2185, Unité de Biochimie des Interactions Macromoléculaires, Département de Biologie Structurale et Chimie, 28 rue du Dr Roux, 75724 Paris Cedex 15, France.
Journal of bacteriology (Impact Factor: 2.69). 07/2011; 193(18):4988-92. DOI: 10.1128/JB.00324-11
Source: PubMed

ABSTRACT FtsL and FtsB are two inner-membrane proteins that are essential constituents of the cell division apparatus of Escherichia coli. In this study, we demonstrate that the leucine zipper-like (LZ) motifs, located in the periplasmic domain of FtsL and FtsB, are required for an optimal interaction between these two essential proteins.

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    ABSTRACT: Escherichia coli cell division is effected by a large assembly of proteins called the divisome, of which a subcomplex consisting of three bitopic inner membrane proteins, FtsQ, FtsB and FtsL, is an essential part. These three proteins, hypothesized to link cytoplasmic to periplasmic events during cell division, contain large periplasmic domains that are of major importance for function and complex formation. The essential nature of this subcomplex, its low abundance and its multiple interactions with key divisome components in the relatively accessible periplasm make it an attractive target for the development of protein-protein interaction inhibitors. Although the crystal structure of the periplasmic domain of FtsQ has been solved, the structure of the FtsQBL complex is unknown with only very crude indications of the interactions in this complex. In this study, we used in vivo site-specific photo cross-linking to probe the surface of the FtsQ periplasmic domain for its interaction interfaces with FtsB and FtsL. An interaction hotspot for FtsB was identified around residue S250 in the C-terminal region of FtsQ and a membrane proximal interaction region for both proteins around residue K59. Sequence alignment revealed a consensus motif overlapping with the C-terminal interaction hotspot underlining the importance of this region in FtsQ. The identification of contact sites in the FtsQBL complex will guide future development of interaction inhibitors that block cell division.
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    Journal of bacteriology 02/2014; DOI:10.1128/JB.01194-13 · 2.69 Impact Factor
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    ABSTRACT: FtsB and FtsL are two essential integral membrane proteins of the bacterial division complex or "divisome", both characterized by a single transmembrane helix and a juxta-membrane coiled coil domain. The two domains are important for the association of FtsB and FtsL, a key event for their recruitment to the divisome, that in turn enables recruitment of the late divisomal components to the Z-ring and subsequent completion of the division process. Here we present a biophysical analysis performed in vitro that shows that the transmembrane domains of FtsB and FtsL associate strongly in isolation. Using FRET, we have measured the oligomerization of fluorophore-labeled transmembrane domains of FtsB and FtsL in both detergent and lipid. The data indicates that the transmembrane helices are likely a major contributor to the stability of the FtsB-FtsL complex. Our analyses show that FtsB and FtsL form a 1:1 higher-order oligomeric complex, possibly a tetramer. This finding suggests that the FtsB-FtsL complex is capable of multi-valent binding to FtsQ and other divisome components, a hypothesis that is consistent with the possibility that the FtsB-FtsL complex has a structural role in the stabilization of the Z-ring.
    Biochemistry 10/2013; 52(43). DOI:10.1021/bi4009837 · 3.19 Impact Factor


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