The Transmembrane Helix of the
            <i>Escherichia coli</i>
            Division Protein FtsI Localizes to the Septal Ring

Wissel, Mark C.; Wendt, Jennifer L.; Mitchell, Calista J.; Weiss, David S.

doi:10.1128/jb.187.7.2558.2005

Cited by 19 publications

(30 citation statements)

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“…This resulted in a complete loss of septal localization. It was later demonstrated that a 26 aa fragment, corresponding roughly to the transmembrane helix of PBP3, is sufficient to direct GFP to the septum of Escherichia coli cells (Wissel et al, 2005). Our results show that a non-functional PBP2x hybrid protein in which the native cytoplasmic and transmembrane domains have been exchanged with the corresponding domains from PBP2b still localizes to the septum (Fig.…”

Section: Discussionsupporting

confidence: 51%

“…This could be due to mislocalization of the protein. It has been reported previously that the membrane anchor of PBP3 (FtsI), which is the Escherichia coli homologue of PBP2x, functions as a cell surface localization signal (Weiss et al, 1999;Wissel et al, 2005). We therefore wondered whether exchanging the native transmembrane segment and cytoplasmic tail of PBP2x with the corresponding regions from PBP2b would interfere with the localization of the resulting hybrid protein.…”

Section: Role Of Membrane-anchoring Domains Of Pbp2x and Pbp2bmentioning

confidence: 98%

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The function of the transmembrane and cytoplasmic domains of pneumococcal penicillin-binding proteins 2x and 2b extends beyond that of simple anchoring devices

2014

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The biosynthesis of cell-wall peptidoglycan is a complex process that involves six different penicillin-binding proteins (PBPs) in Streptococcus pneumoniae. Two of these, PBP2x and PBP2b, are monofunctional transpeptidases that catalyse the formation of peptide cross-links between adjacent glycan strands. Both of them are bitopic membrane proteins with a small cytoplasmic and a large extracellular domain. PBP2x and PBP2b are essential for septal and peripheral peptidoglycan synthesis, respectively. Although several studies have investigated the properties of their extracellular catalytic domains, it is not known whether the role of their N-terminal non-catalytic domains extends beyond that of being simple anchoring devices. We therefore decided to use reciprocal domain swapping and mutational analysis to gain more information about the biological function of the membrane anchors and cytoplasmic tails of PBP2x and PBP2b. In the case of PBP2x both domains are essential, but neither the membrane anchor nor the cytoplasmic domain of PBP2x appear to serve as major localization signals. Instead, our results suggest that they are involved in interactions with other components of the divisome. Mutations of conserved amino acids in the cytoplasmic domain of PBP2x resulted in loss of function, underlining the importance of this region. The cytoplasmic domain of PBP2b could be swapped with the corresponding domain from PBP2x, whereas replacement of the PBP2b transmembrane domain with the corresponding PBP2x domain gave rise to slow-growing cells with grossly abnormal morphology. When both domains were exchanged simultaneously the cells were no longer viable.

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Section: Discussionsupporting

confidence: 51%

Section: Role Of Membrane-anchoring Domains Of Pbp2x and Pbp2bmentioning

confidence: 98%

The function of the transmembrane and cytoplasmic domains of pneumococcal penicillin-binding proteins 2x and 2b extends beyond that of simple anchoring devices

2014

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“…This localization was shown to be dependent on the PBP3 transmembrane domain and cell division proteins FtsZ, -A, -Q, -L, and -W (118,204). Recently it was shown that the transmembrane domain of PBP3 alone localizes to the division septum, with residues on one side of the helix being essential for localization, forming a proposed helix-helix interaction with another division protein (144,209). Using a two-hybrid analysis that is suitable for membrane proteins, Karimova et al identified interactions of PBP3 with several other cell division proteins in E. coli (FtsA, FtsL, FtsN, FtsQ, and FtsW) and an uncharacterized but potential cell division protein (YmgF) (91).…”

Section: Localization Of Pbpsmentioning

confidence: 99%

“…The requirement of FtsW (the putative PG precursor translocase) for recruitment of PBP3 to the division site is particularly well documented (118), and PBP3 localization seems to be dependent on the periplasmic loop located between transmembrane segments 9 and 10 of FtsW (140). The use of truncated forms of PBP3 fused to GFP showed that the transmembrane helix of PBP3 is sufficient to target the fusion protein to the division septum (209). This suggests that the PBP3 transmembrane helix is required for protein-protein interactions that mediate localization, through interaction with another membrane protein such as FtsW or FtsQ.…”

Section: A Model For Pbp Localizationmentioning

confidence: 99%

Bacterial Cell Wall Synthesis: New Insights from Localization Studies

Scheffers

Pinho

2005

Microbiol Mol Biol Rev

539

489

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SUMMARY In order to maintain shape and withstand intracellular pressure, most bacteria are surrounded by a cell wall that consists mainly of the cross-linked polymer peptidoglycan (PG). The importance of PG for the maintenance of bacterial cell shape is underscored by the fact that, for various bacteria, several mutations affecting PG synthesis are associated with cell shape defects. In recent years, the application of fluorescence microscopy to the field of PG synthesis has led to an enormous increase in data on the relationship between cell wall synthesis and bacterial cell shape. First, a novel staining method enabled the visualization of PG precursor incorporation in live cells. Second, penicillin-binding proteins (PBPs), which mediate the final stages of PG synthesis, have been localized in various model organisms by means of immunofluorescence microscopy or green fluorescent protein fusions. In this review, we integrate the knowledge on the last stages of PG synthesis obtained in previous studies with the new data available on localization of PG synthesis and PBPs, in both rod-shaped and coccoid cells. We discuss a model in which, at least for a subset of PBPs, the presence of substrate is a major factor in determining PBP localization.

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“…However, this is not the case for all secreted proteins some of which have no readily identifiable "export signals" or even use "piggy-back" mechanisms or undergo the so called nonclassical secretion (16). Additional secondary structural elements such as TMs (17,18), beta-barrels (19 -21), amphiphilic alpha-helical anchors (22)(23)(24) and functional domains such as peptidoglycan (25,26) and DNA (27,28) binding domains can also serve as indicators of subcellular location.…”

mentioning

confidence: 99%

Proteome-wide Subcellular Topologies of E. coli Polypeptides Database (STEPdb)

Orfanoudaki

Economou

2014

Molecular & Cellular Proteomics

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Cell compartmentalization serves both the isolation and the specialization of cell functions. After synthesis in the cytoplasm, over a third of all proteins are targeted to other subcellular compartments. Knowing how proteins are distributed within the cell and how they interact is a prerequisite for understanding it as a whole. Surface and secreted proteins are important pathogenicity determinants. Here we present the STEP database (STEPdb) that contains a comprehensive characterization of subcellular localization and topology of the complete proteome of Escherichia coli. Two widely used E. coli proteomes (K-12 and BL21) are presented organized into thirteen subcellular classes. STEPdb exploits the wealth of genetic, proteomic, biochemical, and functional information on protein localization, secretion, and targeting in E. coli, one of the best understood model organisms. Subcellular annotations were derived from a combination of bioinformatics prediction, proteomic, biochemical, functional, topological data and extensive literature re-examination that were refined through manual curation. Strong experimental support for the location of 1553 out of 4303 proteins was based on 426 articles and some experimental indications for another 526. Annotations were provided for another 320 proteins based on firm bioinformatic predictions. STEPdb is the first database that contains an extensive set of peripheral IM proteins (PIM proteins) and includes their graphical visualization into complexes, cellular functions, and interactions. It also summarizes all currently known protein export machineries of E. coli K-12 and pairs them, where available, with the secretory proteins that use them. It catalogs the Sec-and TAT-utilizing secretomes and summarizes their topological features such as signal peptides and transmembrane regions, transmembrane topologies and orientations. It also catalogs physicochemical and structural features that influence topology such as abundance, solubility, disorder, heat resistance, and structural domain families. Finally, STEPdb incorporates prediction tools for topology (TMHMM, SignalP, and Phobius) and disorder (IUPred) and implements the BLAST2STEP that performs protein homology searches against the STEPdb. Molecular &

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

Cited by 19 publications

References 0 publications

The function of the transmembrane and cytoplasmic domains of pneumococcal penicillin-binding proteins 2x and 2b extends beyond that of simple anchoring devices

The function of the transmembrane and cytoplasmic domains of pneumococcal penicillin-binding proteins 2x and 2b extends beyond that of simple anchoring devices

Bacterial Cell Wall Synthesis: New Insights from Localization Studies

Proteome-wide Subcellular Topologies of E. coli Polypeptides Database (STEPdb)

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