Evidence of mutualism between two periodontal pathogens: co-operative haem acquisition by the HmuY haemophore of Porphyromonas gingivalis and the cysteine protease interpain A (InpA) of Prevotella intermedia
Evidence of mutualism between two periodontal pathogens: co-operative haem acquisition by the HmuY haemophore of Porphyromonas gingivalis and the cysteine protease interpain A (InpA) of Prevotella intermedia
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DOI：
10.1111/omi.12018
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发表时间：
2013-06-01
影响因子：
3.7
通讯作者：
Smalley, J. W.
中科院分区：
文献类型：
--
作者：
Byrne, D. P.;Potempa, J.;Smalley, J. W.
血红素（铁原卟啉IX）是牙周病原体牙龈卟啉单胞菌和中间普雷沃氏菌必不可少的生长因子和毒力调节剂，它们通过血红蛋白和其他携带血液的血浆蛋白的蛋白水解降解获得血红素。牙龈卟啉卟啉菌的血红蛋白结合血红蛋白和牙龈蛋白酶形成一个独特的合成系统，负责从血红蛋白和甲基血红蛋白中捕获血红素。在这个系统中，血红蛋白是由氧合血红蛋白在牙龈蛋白酶的作用下形成的，血红蛋白是HmuY捕获血红素的易溶底物。本研究探讨了HmuY在血红素获取过程中与pr.m intermedia的半胱氨酸蛋白酶interpain A （InpA）合作的可能性。利用紫外可见光谱和聚丙烯酰胺凝胶电泳，HmuY被证明具有抗蛋白水解能力，因此能够与InpA合作从血红蛋白中提取血红素，血红素被蛋白酶水解转化为血红蛋白。光谱pH滴定表明，铁（II）和铁（III）原卟啉IXHmuY复合物在pH范围410内都是稳定的，这表明血团可以在牙菌斑生物膜中可能遇到的pH范围内发挥作用。这是首次证明细菌血红细胞与另一种细菌的蛋白酶一起从血红蛋白中获取血红素，并可能代表牙龈假单胞菌和中间假单胞菌共同居住在牙周袋中的相互作用。
Haem (iron protoporphyrin IX) is both an essential growth factor and a virulence regulator of the periodontal pathogens Porphyromonas gingivalis and Prevotella intermedia, which acquire it through the proteolytic degradation of haemoglobin and other haem-carrying plasma proteins. The haem-binding lipoprotein HmuY haemophore and the gingipain proteases of P.gingivalis form a unique synthrophic system responsible for capture of haem from haemoglobin and methaemalbumin. In this system, methaemoglobin is formed from oxyhaemoglobin by the activities of gingipain proteases and serves as a facile substrate from which HmuY can capture haem. This study examined the possibility of cooperation between HmuY and the cysteine protease interpain A (InpA) of Pr.intermedia in the haem acquisition process. Using UV-visible spectroscopy and polyacrylamide gel electrophoresis, HmuY was demonstrated to be resistant to proteolysis and so able to cooperate with InpA to extract haem from haemoglobin, which was proteolytically converted to methaemoglobin by the protease. Spectroscopic pH titrations showed that both the iron(II) and iron(III) protoporphyrin IXHmuY complexes were stable over the pH range 410, demonstrating that the haemophore could function over a range of pH that may be encountered in the dental plaque biofilm. This is the first demonstration of a bacterial haemophore working in conjunction with a protease from another bacterial species to acquire haem from haemoglobin and may represent mutualism between P.gingivalis and Pr. intermedia co-inhabiting the periodontal pocket.