Multidrug-resistant Acinetobacter baumannii has recently emerged as an important pathogen in nosocomial infection; thus, effective antimicrobial regimens are urgently needed. Human antimicrobial peptides (AMPs) exhibit multiple functions and antimicrobial activities against bacteria and fungi and are proposed to be potential adjuvant therapeutic agents. This study examined the effect of the hum...

We discovered a new small non-coding RNA (sRNA) gene, vrrA of Vibrio cholerae O1 strain A1552. A vrrA mutant overproduces OmpA porin, and we demonstrate that the 140 nt VrrA RNA represses ompA translation by base-pairing with the 5' region of the mRNA. The RNA chaperone Hfq is not stringently required for VrrA action, but expression of the vrrA gene requires the membrane stress sigma factor, si...

Chlamydia trachomatis is the leading cause of bacterial sexually transmitted diseases worldwide. Urogenital strains are classified into serotypes and genotypes based on the major outer membrane protein and its gene, ompA, respectively. Studies of the association of serotypes with clinical signs and symptoms have produced conflicting results while no studies have evaluated associations with ompA...

Coxiella burnetii is the agent of the emerging zoonosis Q fever. This pathogen invades phagocytic and non-phagocytic cells and uses a Dot/Icm secretion system to co-opt the endocytic pathway for the biogenesis of an acidic parasitophorous vacuole where Coxiella replicates in large numbers. The study of the cell biology of Coxiella infections has been severely hampered by the obligate intracellu...

E. coli O157:H7, one of the major EHEC serotypes, is capable of developing bloody diarrhea, hemorrhagic colitis (HC), and fatal hemolytic uremic syndrome (HUS) and is accompanied by high annual economic loss worldwide. Due to the increased risk of HC and HUS development following antibiotic therapy, the prevention of infections caused by this pathogen is considered to be one of the most effecti...

The outer membrane protein OmpA of Escherichia coli K-12 serves as a receptor for a number of T-even-like phages. We have isolated a series of ompA mutants which are resistant to such phages but which still produce the OmpA protein. None of the mutants was able to either irreversibly or reversibly bind the phage with which they had been selected. Also, the OmpA protein is required for the actio...

The folding mechanism of outer membrane proteins (OMPs) of Gram-negative bacteria into lipid bilayers has been studied using OmpA of E. coli and FomA of F. nucleatum as examples. Both, OmpA and FomA are soluble in unfolded form in urea and insert and fold into phospholipid bilayers upon strong dilution of the denaturant urea. OmpA is a structural protein and forms a small ion channel, composed ...

Outer membrane protein A (OmpA) of Escherichia coli is a beta-barrel membrane protein that unfolds in 8 M urea to a random coil. OmpA refolds upon urea dilution in the presence of certain detergents or lipids. To examine the minimal requirements for secondary and tertiary structure formation in beta-barrel membrane proteins, folding of OmpA was studied as a function of the hydrophobic chain len...

The onset and progressive pathogenesis of periodontal disease is thought to be initiated by the entry of Aggregatibacter actinomycetemcomitans (Aa) into periodontal tissue, especially gingival epithelium. Nonetheless, the mechanism underlying such bacterial entry remains to be clarified. Therefore, this study aimed to investigate the possible role of Aa outer membrane protein 29 kD (Omp29), a h...

Esherichia coli, the most common gram-negative bacteria, can penetrate the brain microvascular endothelial cells (BMECs) during the neonatal period to cause meningitis with significant morbidity and mortality. Experimental studies have shown that outer-membrane protein A (OmpA) of E. coli plays a key role in the initial steps of the invasion process by binding to specific sugar moieties present...