Capestany Cindy A, Tribble Gena D, Maeda Kazuhiko, Demuth Donald R, Lamont Richard J
Department of Oral Biology, College of Dentistry, University of Florida, Gainesville, FL 32610-0424, USA.
J Bacteriol. 2008 Feb;190(4):1436-46. doi: 10.1128/JB.01632-07. Epub 2007 Dec 7.
Clp proteases and chaperones are ubiquitous among prokaryotes and eukaryotes, and in many pathogenic bacteria the Clp stress response system is also involved in regulation of virulence properties. In this study, the roles of ClpB, ClpC, and ClpXP in stress resistance, homotypic and heterotypic biofilm formation, and intracellular invasion in the oral opportunistic pathogen Porphyromonas gingivalis were investigated. Absence of ClpC and ClpXP, but not ClpB, resulted in diminished tolerance to high temperatures. Response to oxidative stress was not affected by the loss of any of the Clp proteins. The clpC and clpXP mutants demonstrated elevated monospecies biofilm formation, and the absence of ClpXP also enhanced heterotypic P. gingivalis-Streptococcus gordonii biofilm formation. All clp mutants adhered to gingival epithelial cells to the same level as the wild type; however, ClpC and ClpXP were found to be necessary for entry into host epithelial cells. ClpB did not play a role in entry but was required for intracellular replication and survival. ClpXP negatively regulated the surface exposure of the minor fimbrial (Mfa) protein subunit of P. gingivalis, which stimulates biofilm formation but interferes with epithelial cell entry. Collectively, these results show that the Clp protease complex and chaperones control several processes that are important for the colonization and survival of P. gingivalis in the oral cavity.
Clp蛋白酶和伴侣蛋白在原核生物和真核生物中普遍存在，并且在许多致病细菌中，Clp应激反应系统也参与毒力特性的调控。在本研究中，我们调查了ClpB、ClpC和ClpXP在口腔机会致病菌牙龈卟啉单胞菌的应激抗性、同型和异型生物膜形成以及细胞内侵袭中的作用。ClpC和ClpXP的缺失而非ClpB的缺失导致对高温的耐受性降低。氧化应激反应不受任何Clp蛋白缺失的影响。clpC和clpXP突变体表现出单菌种生物膜形成增加，并且ClpXP的缺失还增强了牙龈卟啉单胞菌与戈登链球菌的异型生物膜形成。所有clp突变体与野生型一样能黏附到牙龈上皮细胞；然而，发现ClpC和ClpXP是进入宿主上皮细胞所必需的。ClpB在进入过程中不起作用，但对于细胞内复制和存活是必需的。ClpXP负向调节牙龈卟啉单胞菌次要菌毛（Mfa）蛋白亚基的表面暴露，该亚基刺激生物膜形成但干扰上皮细胞进入。总的来说，这些结果表明Clp蛋白酶复合体和伴侣蛋白控制着对牙龈卟啉单胞菌在口腔中的定植和存活很重要的几个过程。
