A Transposon Screen Identifies Genetic Determinants of Vibrio cholerae Resistance to High-Molecular-Weight Antibiotics.

Gram-negative bacteria are notoriously resistant to a variety of high-molecular-weight antibiotics due to the limited permeability of their outer membrane (OM). The basis of OM barrier function and the genetic factors required for its maintenance remain incompletely understood. Here, we employed transposon insertion sequencing to identify genes required for Vibrio cholerae resistance to vancomycin and bacitracin, antibiotics that are thought to be too large to efficiently penetrate the OM.

Molecular Dissection of the Essential Features of the Origin of Replication of the Second Vibrio cholerae Chromosome.

Unlabelled: Vibrionaceae family members are interesting models for studying DNA replication initiation, as they contain two circular chromosomes. Chromosome II (chrII) replication is governed by two evolutionarily unique yet highly conserved elements, the origin DNA sequence oriCII and the initiator protein RctB. The minimum functional region of oriCII, oriCII-min, contains multiple elements that are bound by RctB in vitro, but little is known about the specific requirements for individual elements during oriCII initiation.

Regulatory cross-talk links Vibrio cholerae chromosome II replication and segregation.

There is little knowledge of factors and mechanisms for coordinating bacterial chromosome replication and segregation. Previous studies have revealed that genes (and their products) that surround the origin of replication (oriCII) of Vibrio cholerae chromosome II (chrII) are critical for controlling the replication and segregation of this chromosome. rctB, which flanks one side of oriCII, encodes a protein that initiates chrII replication; rctA, which flanks the other side of oriCII, inhibits rctB activity.

Self-enhanced accumulation of FtsN at Division Sites and Roles for Other Proteins with a SPOR domain (DamX, DedD, and RlpA) in Escherichia coli cell constriction.

Of the known essential division proteins in Escherichia coli, FtsN is the last to join the septal ring organelle. FtsN is a bitopic membrane protein with a small cytoplasmic portion and a large periplasmic one. The latter is thought to form an alpha-helical juxtamembrane region, an unstructured linker, and a C-terminal, globular, murein-binding SPOR domain.

The trans-envelope Tol-Pal complex is part of the cell division machinery and required for proper outer-membrane invagination during cell constriction in E. coli.

Fission of bacterial cells involves the co-ordinated invagination of the envelope layers. Invagination of the cytoplasmic membrane (IM) and peptidoglycan (PG) layer is likely driven by the septal ring organelle. Invagination of the outer membrane (OM) in Gram-negative species is thought to occur passively via its tethering to the underlying PG layer with generally distributed PG-binding OM (lipo)proteins.