Urick Tonia, I-Chang Chien, Arena Ellen, Xu Wenlian, Bessman Maurice J, Ruffolo Carmel G
Department of Biological Sciences, University of Wisconsin-Parkside, P.O. Box 2000, Kenosha, WI 53144, USA.
J Bacteriol. 2005 Aug;187(16):5809-17. doi: 10.1128/JB.187.16.5809-5817.2005.
The pnhA gene of Pasteurella multocida encodes PnhA, which is a member of the Nudix hydrolase subfamily of dinucleoside oligophosphate pyrophosphatases. PnhA hydrolyzes diadenosine tetra-, penta-, and hexaphosphates with a preference for diadenosine pentaphosphate, from which it forms ATP and ADP. PnhA requires a divalent metal cation, Mg(2+) or Mn(2+), and prefers an alkaline pH of 8 for optimal activity. A P. multocida strain that lacked a functional pnhA gene, ACP13, was constructed to further characterize the function of PnhA. The cellular size of ACP13 was found to be 60% less than that of wild-type P. multocida, but the growth rate of ACP13 and its sensitivity to heat shock conditions were similar to those of the wild type, and the wild-type cell size was restored in the presence of a functional pnhA gene. Wild-type and ACP13 strains were tested for virulence by using the chicken embryo lethality model, and ACP13 was found to be up to 1,000-fold less virulent than the wild-type strain. This is the first study to use an animal model in assessing the virulence of a bacterial strain that lacked a dinucleoside oligophosphate pyrophosphatase and suggests that the pyrophosphatase PnhA, catalyzing the hydrolysis of diadenosine pentaphosphates, may also play a role in facilitating P. multocida pathogenicity in the host.
多杀性巴氏杆菌的pnhA基因编码PnhA，它是二核苷寡磷酸焦磷酸酶的Nudix水解酶亚家族的成员。PnhA水解二腺苷四磷酸、五磷酸和六磷酸，优先水解二腺苷五磷酸，从中形成ATP和ADP。PnhA需要二价金属阳离子Mg(2+)或Mn(2+)，并且最适活性的pH值为8。构建了一株缺乏功能性pnhA基因的多杀性巴氏杆菌菌株ACP13，以进一步表征PnhA的功能。发现ACP13的细胞大小比野生型多杀性巴氏杆菌小60%，但ACP13的生长速率及其对热休克条件的敏感性与野生型相似，并且在存在功能性pnhA基因的情况下野生型细胞大小得以恢复。通过使用鸡胚致死模型测试野生型和ACP13菌株的毒力，发现ACP13的毒力比野生型菌株低多达1000倍。这是第一项使用动物模型评估缺乏二核苷寡磷酸焦磷酸酶的细菌菌株毒力的研究，表明催化二腺苷五磷酸水解的焦磷酸酶PnhA也可能在促进多杀性巴氏杆菌在宿主体内的致病性中发挥作用。
