Bacterial membrane dynamics:Compartmentalization and repair

In every bacterial cell, the plasma membrane plays a key role in viability as it forms a selective barrier between the inside of the cell and its environment. This barrier function depends on the physical state of the lipid bilayer and the proteins embedded or associated with the bilayer. Over the past decade or so, it has become apparent that many membrane-organizing proteins and principles, which were described in eukaryote systems, are ubiquitous and play important roles in bacterial cells. In this minireview, we focus on the enigmatic roles of bacterial flotillins in membrane compartmentalization and bacterial dynamins and ESCRT-like systems in membrane repair and remodeling.</p

The Cell Wall of Bacillus subtilis

The cell wall of Bacillus subtilis is a rigid structure on the outside of the cell that forms the first barrier between the bacterium and the environment, and at the same time maintains cell shape and withstands the pressure generated by the cell's turgor. In this review, the chemical composition of peptidoglycan, teichoic and teichuronic acids, the polymers that comprise the cell wall, and the biosynthetic pathways involved in their synthesis will be discussed, as well as the architecture of the cell wall. B. subtilis has been the first bacterium for which the role of an actin-like cytoskeleton in cell shape determination and peptidoglycan synthesis was identified and for which the entire set of peptidoglycan synthesizing enzymes has been localised. The role of the cytoskeleton in shape generation and maintenance will be discussed and results from other model organisms will be compared to what is known for B. subtilis. Finally, outstanding questions in the field of cell wall synthesis will be discussed

LipidII:Just Another Brick in the Wall?

Nearly all bacteria contain a peptidoglycan cell wall. The peptidoglycan precursor molecule is LipidII, containing the basic peptidoglycan building block attached to a lipid. Although the suitability of LipidII as an antibacterial target has long been recognized, progress on elucidating the role(s) of LipidII in bacterial cell biology has been slow. The focus of this review is on exciting new developments, both with respect to antibacterials targeting LipidII as well as the emerging role of LipidII in organizing the membrane and cell wall synthesis. It appears that on both sides of the membrane, LipidII plays crucial roles in organizing cytoskeletal proteins and peptidoglycan synthesis machineries. Finally, the recent discovery of no less than three different categories of LipidII flippases will be discussed

A 1 MDa protein complex containing critical components of the Escherichia coli divisome

Cell division in bacteria is an essential process that is carried out at mid-cell by a group of cell division proteins referred to as the divisome. In Escherichia coli, over two dozen cell division proteins have been identified of which ten are essential. These division proteins localize sequentially and interdependently to the division site, after which constriction eventually produces two daughter cells. Various genetic and biochemical techniques have identified many interactions amongst cell division proteins, however the existence of the divisome as a large multi-protein complex has never been shown. Here, we identify a 1 MDa protein complex by native page that contains seven essential cell division proteins (FtsZ, ZipA, FtsK, FtsQ, FtsB, FtsL, and FtsN). The 1 MDa complex is present in rapidly dividing cells, but absent when cultures enter the stationary growth phase. Slight overexpression of the ftsQ D237N mutation that blocks cell division prevents formation of this 1 MDa complex. In cells depleted of FtsN, the 1 MDa complex is not assembled. Combined, our findings indicate that a large protein complex containing many different cell division proteins indeed exists. We note that this complex is very fragile and sensitive to the expression of tagged versions of FtsQ

An organogold compound as potential antimicrobial agent against drug resistant bacteria:Initial mechanistic insights

The rise of antimicrobial resistance has necessitated novel strategies to efficiently combat pathogenic bacteria. Metal‐based compounds have been proven as a possible alternative to classical organic drugs. Here, we have assessed the antibacterial activity of seven gold complexes of different families. One compound, a cyclometalated Au(III) C^N complex, showed activity against Gram‐positive bacteria, including multi‐drug resistant clinical strains. The mechanism of action of this compound was studied in Bacillus subtilis. Overall, the studies point towards a complex mode of antibacterial action, which does not include induction of oxidative stress or cell membrane damage. A number of genes related to metal transport and homeostasis were upregulated upon short treatment of the cells with gold compound. Toxicity tests conducted on precision‐cut mouse tissue slices ex vivo revealed that the organogold compound is poorly toxic to mouse liver and kidney tissues, and may thus, be treated as an antibacterial drug candidate