Recognition of 2′-hydroxyl groups by Escherichia coli ribonuclease HI

AbstractIn order to investigate the hydrogen-bonding interactions between Escherichia coli ribonuclease HI and the 2′-hydroxyl functions of the substrate, oligonucleotide duplexes containing 2′-amino-2′-deoxyuridine or 2′-fluoro-2′-deoxyuridine at a specific site were used, and their affinities for the enzyme were determined by kinetic analyses. The results indicate that the hydroxyl groups of the nucleoside 3′-adjacent to the cleaved phosphodiester linkage and the second nucleoside 5′ to the cleaved phosphodiester act as both a proton donor and an acceptor and as a proton acceptor, respectively, in the enzyme-substrate complex. A molecular model was constructed using the interactions derived from the results

Temporal differences of onset between primary skin lesions and regional lymph node lesions for tularemia in Japan: a clinicopathologic and immunohistochemical study of 19 skin cases and 54 lymph node cases

For tularemia, a zoonosis caused by the gram-negative coccobacillus Francisella tularensis, research of the relation between skin lesions and lymph node lesions has not been reported in the literature. This report describes skin lesions and lymph node lesions and their mutual relation over time for tularemia in Japan. Around the second day after infection (DAI), a subcutaneous abscess was observed (abscess form). Hand and finger skin ulcers formed during the second to the fourth week. Subcutaneous and dermal granulomas were observed with adjacent monocytoid B lymphocytes (MBLs) (abscess–granulomatous form). From the sixth week, large granulomas with central homogeneous lesions emerged diffusely (granulomatous form). On 2–14 DAI, F. tularensis antigen in skin lesions was detected in abscesses. During 7–12 DAI, abscesses with adjacent MBLs appeared without epithelioid granuloma (abscess form) in regional lymph nodes. During the second to fifth week, granulomas appeared with necrosis (abscess–granulomatous form). After the sixth week, large granulomas with a central homogeneous lesion (granulomatous form) appeared. F. tularensis antigen in lymph node lesions was observed in the abscess on 7–92 DAI. Apparently, F. tularensis penetrates the finger skin immediately after contact with infected hares. Subsequently, the primary lesion gradually transfers from skin to regional lymph nodes. The regional lymph node lesions induced by skin lesion are designated as dermatopathic lymphadenopathy. This study revealed temporal differences of onset among the skin and lymph node lesions