Molecular characterization of the EhaG and UpaG trimeric autotransporter proteins from pathogenic Escherichia coli

Trimeric autotransporter proteins (TAAs) are important virulence factors of many Gram-negative bacterial pathogens. A common feature of most TAAs is the ability to mediate adherence to eukaryotic cells or extracellular matrix (ECM) proteins via a cell surface-exposed passenger domain. Here we describe the characterization of EhaG, a TAA identified from enterohemorrhagic Escherichia coli (EHEC) O157:H7. EhaG is a positional orthologue of the recently characterized UpaG TAA from uropathogenic E. coli (UPEC). Similarly to UpaG, EhaG localized at the bacterial cell surface and promoted cell aggregation, biofilm formation, and adherence to a range of ECM proteins. However, the two orthologues display differential cellular binding: EhaG mediates specific adhesion to colorectal epithelial cells while UpaG promotes specific binding to bladder epithelial cells. The EhaG and UpaG TAAs contain extensive sequence divergence in their respective passenger domains that could account for these differences. Indeed, sequence analyses of UpaG and EhaG homologues from several E. coli genomes revealed grouping of the proteins in clades almost exclusively represented by distinct E. coli pathotypes. The expression of EhaG (in EHEC) and UpaG (in UPEC) was also investigated and shown to be significantly enhanced in an hns isogenic mutant, suggesting that H-NS acts as a negative regulator of both TAAs. Thus, while the EhaG and UpaG TAAs contain some conserved binding and regulatory features, they also possess important differences that correlate with the distinct pathogenic lifestyles of EHEC and UPEC

The Effect of Megan\u27s Law on Sex Offender Reintegration

The purpose of this study is to better understand the positive and negative, intended and unintended, consequences of community notification on sex offenders\u27 rehabilitation and reintegration. A sample of 183 convicted male sex offenders from Florida completed the survey. Overall, about one third of participants had experienced dire events, such as the loss of a job or home, threats or harassment, or property damage. Physical assaultwas a relatively rare occurrence. The majority identified negative effects, such as stress, isolation, loss of relationships, fear, shame, embarrassment, and hopelessness. Some participants noted positive effects of Megan\u27s Law, including motivation to prevent reoffense and increased honesty with friends and family. Fewsex offenders believed that communities are safer because of Megan\u27s Law, and more than half reported that the information posted about them on Florida\u27s Internet registry was incorrect. Implications for practice and policy are discussed