RESUMO
HlyU is a transcription factor of the ArsR/SmtB family and activates the expression of the pathogenic Vibrio vulnificus RTX toxin. In contrast to the other metal-responding ArsR/SmtB proteins, HlyU does not sense metal ions. To provide its structural information, we elucidated the crystal structure of HlyU from V. vulnificus CMCP6 (HlyU_Vv). The monomeric HlyU_Vv architecture of five alpha-helices and two beta-strands, some of which constitute a typical DNA-binding winged helix-turn-helix (wHTH) motif, is very similar to that of other transcription regulators. Nonetheless, the homo-dimeric HlyU_Vv structure shows several different, three-dimensional features in the spatial position and the detailed dimeric interaction, which were not observed in the modeling study based on the same protein family and sequence similarity.
Assuntos
Fatores de Hemolisina/química , Vibrio vulnificus , Sequência de Aminoácidos , Sítios de Ligação , Cristalografia por Raios X , DNA Bacteriano/metabolismo , Fatores de Hemolisina/metabolismo , Metais Pesados/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Ligação Proteica , Conformação Proteica , Multimerização Proteica , Homologia de Sequência de Aminoácidos , Transativadores/química , Transativadores/metabolismo , Vibrio vulnificus/genética , Vibrio vulnificus/metabolismoRESUMO
A retrospective study was conducted to determine case histories, microbiological characteristics, and molecular subtypes associated with Listeria monocytogenes infections of the eye in large animals. For selected cases, environmental L. monocytogenes contamination patterns on case farms were also evaluated to probe for potential sources and spread of listerial eye infections. Records of 170 L. monocytogenes isolates from animal infections were reviewed to determine the fraction of isolates associated with eye infections (conjunctivitis, keratitis, and uveitis) of animals and to gather information on the clinical history of these cases. Overall, 4 of 170 Listeria monocytogenes isolates were associated with eye infections; 3 of these had occurred in cows and 1 in a horse. Molecular subtyping (by EcoRI ribotying) showed that 4 different L. monocytogenes subtypes were isolated from these 4 cases; the same ribotypes had previously been found among invasive animal listeriosis infections. Although a variety of L. monocytogenes subtypes were isolated from environmental sources, on 1 farm, the same ribotype associated with the eye infection was also isolated from a fecal sample of a healthy animal and from a soil sample. The data reported in this study further suggest that L. monocytogenes can be a cause of eye infections in several animal species. Listerial eye infections do not seem to require specific pathogen-related virulence characteristics but rather seem to be a function of environmental or host factors, such as direct exposure of the eyes of susceptible animals to high numbers of the pathogen. Although listerial eye infections are rarely diagnosed because of its ubiquitous nature, L. monocytogenes may have to be considered more commonly as a causative agent of eye infections in ruminants and horses.
Assuntos
Doenças dos Bovinos/microbiologia , Infecções Oculares Bacterianas/veterinária , Doenças dos Cavalos/microbiologia , Listeria monocytogenes/isolamento & purificação , Listeriose/veterinária , Animais , Bovinos , DNA Bacteriano/química , DNA Bacteriano/genética , Exposição Ambiental , Infecções Oculares Bacterianas/microbiologia , Feminino , Fatores de Hemolisina/química , Fatores de Hemolisina/genética , Cavalos , Listeria monocytogenes/genética , Listeriose/microbiologia , Reação em Cadeia da Polimerase/veterinária , Polimorfismo Genético , Polimorfismo de Fragmento de Restrição , Estudos Retrospectivos , Ribotipagem/veterináriaRESUMO
Exosubstances (cohemolysins) produced by Streptococcus agalactiae (CAMP-factor) and Streptococcus uberis (Uberis-factor) showing hemolytic synergism with beta-lysin produced by Staphylococcus aureus were compared. Cohemolytic activity was evaluated in the supernatants of bacterial cultures, before and after ammonium sulfate precipitation. Sheep erythrocytes sensitized with beta-lysin were used as substrate. The assays were performed in microtiter plates and results were expressed as cohemolytic units/ml. Maximum cohemolytic activity was detected, respectively, after 8 h and 14 h of growth in Columbia broth in S. uberis and S. agalactiae cultures. Cohemolytic activities of both microorganisms showed similarities when submitted to various physical and chemical treatments. They were significantly decreased by heating at 60 degrees C and 100 degrees C, or in presence of trypsin, and were abolished in the presence of Tween 20. Activities were found to be stable in crude supernatants and concentrated preparations maintained at -20 degrees C for 3 months. Differences were related to levels of activity and kinetics of detection during the growth cycle. The results indicate the proteic nature, at least in part, of the Uberis factor. Analysis by PAGE in the presence or absence of SDS allowed us to correlate Uberis activity with a protein band with apparent molecular mass of 42 kDa, while CAMP activity was associated with a protein band of 27 kDa.
