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首页> 外文期刊>Infection and immunity >Characterization of a Tn4351-generated hemin uptake mutant of Porphyromonas gingivalis: evidence for the coordinate regulation of virulence factors by hemin.
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Characterization of a Tn4351-generated hemin uptake mutant of Porphyromonas gingivalis: evidence for the coordinate regulation of virulence factors by hemin.

机译：Tn4351生成的牙龈卟啉单胞菌的血红素摄取突变体的表征：血红素对毒力因子的协调调节的证据。

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The ability of Porphyromonas gingivalis to acquire iron in the iron-limited environment of the host is crucial to the colonization of this organism. We report here on the isolation and characterization of a transpositional insertion mutant of P. gingivalis A7436 (designated MSM-3) which is defective in the utilization and transport of hemin. P. gingivalis MSM-3 was selected on the basis of its nonpigmented phenotype on anaerobic blood agar following mutagenesis with the Bacteroides fragilis transposon Tn4351. P. gingivalis MSM-3 grew poorly when supplied with hemin as a sole source of iron; however, growth was observed with hemoglobin or inorganic iron. P. gingivalis MSM-3 grown in either hemin-replete or hemin-depleted conditions bound and transported less [14C]hemin or [59Fe]hemin than did the parent strain. At 4 h, P. gingivalis MSM-3 grown in hemin-replete conditions transported only 10,000 pmol of hemin per mg of protein, or 14% of the amount transported by P. gingivalis A7436. Unlike P. gingivalis A7436, hemin binding and transport by P. gingivalis MSM-3 were not tightly regulated by hemin or iron. Examination of P. gingivalis MSM-3 cultures by electron microscopy revealed an overproduction of membrane vesicles, and determination of the dry weight of purified vesicles indicated that P. gingivalis MSM-3 produced twice as much membrane vesicles as did strain A7436. Extracellular vesicles isolated from P. gingivalis MSM-3 also were found to express increased hemolytic and trypsin-like protease activities compared with the parent strain. When inoculated into subcutaneous chambers implanted in mice, P. gingivalis MSM-3 was highly infectious and more invasive than the parent strain, as indicated by secondary lesion formation and death. Taken together, these results indicate that the decreased transport of hemin by P. gingivalis MSM-3 results in the increased expression of several virulence factors which may be coordinately regulated by hemin.
机译：牙龈卟啉单胞菌在宿主的铁受限环境中获得铁的能力对于该生物的定殖至关重要。我们在此报告了牙龈卟啉单胞菌A7436（称为MSM-3）的转座插入突变体的分离和表征，该突变体在血红素的利用和运输中存在缺陷。在用脆弱的拟杆菌（Bacteroides fragilis）转座子Tn4351诱变后，根据厌氧血琼脂上无色素表型选择牙龈卟啉单胞菌MSM-3。牙龈卟啉单胞菌MSM-3补充有血红素作为唯一的铁源时生长缓慢。然而，观察到血红蛋白或无机铁的生长。在贫血红素或贫血贫血条件下生长的牙龈卟啉单胞菌MSM-3与亲本菌株相比，结合和转运的[14C] hemin或[59Fe] hemin更少。在4 h时，在富含血红素的条件下生长的牙龈卟啉单胞菌MSM-3每毫克蛋白质仅运送10,000 pmol的血红素，占牙龈卟啉单胞菌A7436运送量的14％。与牙龈卟啉单胞菌A7436不同，牙龈卟啉单胞菌MSM-3的血红素结合和转运不受血红素或铁的严格调控。通过电子显微镜检查牙龈卟啉单胞菌MSM-3培养物显示出膜囊泡的过量产生，并且对纯化的囊泡的干重的测定表明牙龈卟啉单胞菌MSM-3产生的膜囊泡是菌株A7436的两倍。与亲本菌株相比，还发现从牙龈卟啉单胞菌MSM-3分离的细胞外囊泡表达增加的溶血和胰蛋白酶样蛋白酶活性。如继发性病变形成和死亡所示，当将牙龈卟啉单胞菌MSM-3接种到植入小鼠的皮下腔室中时，其感染性和侵袭性均比亲代菌株高。两者合计，这些结果表明牙龈卟啉单胞菌MSM-3减少的血红素运输导致几种毒力因子的表达增加，这些毒力因子可能由血红素协同调节。

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