In gram-negative bacteria, high-affinity iron uptake requires the TonB/ExbB/ExbD envelope complex to release iron chelates from their specific outer membrane receptors into the periplasm. Based on sequence similarities, the Bordetella pertussis tonB exbB exbD locus was identified on a cloned DNA fragment. The tight organization of the three genes suggests that they are cotranscribed. A putative...

Polygalacturonase (PG) was purified from Erwinia carotovora EC. A hybrid cosmid, pSH711, that encodes PG activity but not pectate lyase activity was identified from an E. carotovora genomic library by an immunological screening method. A cell extract of Escherichia coli cells containing pSH711 was able to produce plant tissue maceration when spotted on carrot, potato, or turnip slices. In addit...

Fitness costs associated with resistance or virulence genes are thought to play a key role in determining the dynamics of gene-for-gene (GFG) host-parasite coevolution. However, the nature of interactions between fitness effects of multiple resistance or virulence genes (epistasis) has received less attention. To examine effects of the functional form of epistasis on the dynamics of GFG host-pa...

The Burkholderia cepacia complex (Bcc) is a group of genetically related environmental bacteria that can cause chronic opportunistic infections in patients with cystic fibrosis (CF) and other underlying diseases. These infections are difficult to treat due to the inherent resistance of the bacteria to antibiotics. Bacteria can spread between CF patients through social contact and sometimes caus...

Infections caused by multiple organisms, or polymicrobial infections, are likely more common than is broadly appreciated. Interaction among microbial communities (and with their host) can change the infection landscape by subverting immunity, providing nutrients and inhibiting competing microbes. Stacy et al. (A. Stacy, D. Fleming, R. J. Lamont, K. P. Rumbaugh, and M. Whiteley, mBio 7:e00782-16...

The major virulence determinant of the rodent malaria parasite, Plasmodium yoelii, has remained unresolved since the discovery of the lethal line in the 1970s. Because virulence in this parasite correlates with the ability to invade different types of erythrocytes, we evaluated the potential role of the parasite erythrocyte binding ligand, PyEBL. We found 1 amino acid substitution in a domain r...

Carbon catabolite protein A (CcpA) is known to function as a major regulator of gene expression in different gram-positive organisms. Deletion of the ccpA homologue (saCOL1786) in Staphylococcus aureus was found to affect growth, glucose metabolization, and transcription of selected virulence determinants. In liquid culture, deletion of CcpA decreased the growth rate and yield; however, the eff...

Granulomas are organized host immune structures composed of tightly interposed macrophages and other cells that form in response to a variety of persistent stimuli, both infectious and noninfectious. The tuberculous granuloma is essential for host containment of mycobacterial infection, although it does not always eradicate it. Therefore, it is considered a host-beneficial, if incompletely effi...