RESUMEN
The genome sequence of the Salmonella enterica serovar Anatum-specific, serotype-converting bacteriophage epsilon15 has been completed. The nonredundant genome contains 39,671 bp and 51 putative genes. It most closely resembles the genome of phiV10, an Escherichia coli O157:H7-specific temperate phage, with which it shares 36 related genes. More distant relatives include the Burkholderia cepacia-specific phage, BcepC6B (8 similar genes), the Bordetella bronchiseptica-specific phage, BPP-1 (8 similar genes) and the Photobacterium profundum prophage, P Pphipr1 (6 similar genes). epsilon15 gene identifications based on homologies with known gene families include the terminase small and large subunits, integrase, endolysin, two holins, two DNA methylase enzymes (one adenine-specific and one cytosine-specific) and a RecT-like enzyme. Genes identified experimentally include those coding for the serotype conversion proteins, the tail fiber, the major capsid protein and the major repressor. epsilon15's attP site and the Salmonella attB site with which it interacts during lysogenization have also been determined.
Asunto(s)
Genoma Viral , Fagos de Salmonella/genética , Salmonella enterica/virología , Secuencia de Aminoácidos , Tipificación de Bacteriófagos , Secuencia de Bases , ADN Bacteriano/genética , ADN Viral/genética , Datos de Secuencia Molecular , Fagos de Salmonella/clasificación , Fagos de Salmonella/fisiología , Salmonella enterica/clasificación , Salmonella enterica/genética , Homología de Secuencia de Ácido Nucleico , Serotipificación , Especificidad de la Especie , Proteínas Virales/genética , Ensamble de Virus , Integración ViralRESUMEN
OBJECTIVE: Monosodium urate monohydrate (MSU) crystals have remarkable inflammatory potential. However, gouty inflammation is spontaneously self-limited, an occurrence recognized since antiquity. Gouty synovitis is driven and sustained by neutrophil influx. Importantly, macrophage phagocytosis of apoptotic (but not necrotic) neutrophils is antiinflammatory. Therefore, we tested the hypothesis that efficient clearance of apoptotic neutrophils by macrophages is one of the factors that restrains the progression of gouty inflammation. Macrophage expression of transglutaminase 2 (TG2), a multifunctional protein with reciprocally regulated transamidation and purine nucleotide-binding activities, promotes apoptotic leukocyte uptake. In this study, we tested the specific role of macrophage TG2 expression in MSU crystal-induced inflammation. METHODS: We studied MSU crystal-induced peritonitis in TG2-/- and congenic TG2+/+ mice. We also studied the effects of TG2 on apoptotic cell uptake by cultured macrophages. RESULTS: TG2-/- mice demonstrated more progressive neutrophilic accumulation than did TG2+/+ mice, which was associated with delayed clearance of apoptotic neutrophils during MSU crystal-induced peritonitis. We observed defective phagocytosis of apoptotic leukocytes by TG2-/- peritoneal macrophages, which was corrected by soluble extracellular TG2. Transamidation catalytic activity of TG2 was not required to mediate macrophage uptake of apoptotic leukocytes. In contrast, the TG2 nucleotide binding site residue K173 was critical for this TG2 function. TG2 bound to GDP, ADP, or ATP (but not to GTP) rescued defective apoptotic leukocyte uptake by TG2-/- macrophages. CONCLUSION: Enhancement of apoptotic neutrophil uptake by macrophage-derived TG2 restrains gout-like neutrophilic peritoneal inflammation. Differential binding of TG2 by purine nucleotides may contribute to clinical variability in the extent and duration of gouty inflammation.