Nepomuceno R S L, Tavares M B, Lemos J A, Griswold A R, Ribeiro J L, Balan A, Guimarães K S, Cai S, Burne R A, Ferreira L C S, Ferreira R C C
Department of Microbiology, Biomedical Sciences Institute, University of São Paulo, Cidade Universitária, SP, Brazil.
Oral Microbiol Immunol. 2007 Aug;22(4):277-84. doi: 10.1111/j.1399-302X.2007.00368.x.
The Opp system is an ATP-binding cassette-type transporter formed by membrane-associated proteins required for the uptake of oligopeptides in bacteria. In gram-positive bacteria, the Opp system, and particularly the oligopeptide-binding protein (OppA), has been shown to be involved in different aspects of cell physiology, including intercellular communication and binding to host proteins.
In the present study we began to investigate the Opp system of Streptococcus mutans, the main etiological agent of dental caries.
Five opp genes (oppABCDF) organized in a single operon were identified in the genome of the S. mutans UA159 strain. Amino acid sequence analyses showed that the S. mutans OppA is closely related to an ortholog found in Streptococcus agalactiae. Incubation of S. mutans UA159 cells with an anti-OppA-specific serum did not inhibit biofilm formation on polystyrene plates. Moreover, S. mutans UA159 derivatives carrying deletions on the oppA or oppB genes did not show significant growth impairment, increased sensitivity to aminopterin, or defective capacity to form biofilms on polystyrene wells in the presence or not of saliva. Remarkably, only two out of three laboratory strains and one out of seven clinical strains recovered from tooth decay processes harbored a copy of the oppA gene and expressed the OppA protein.
Collectively, these results indicate that, in contrast to other Streptococcus species, the S. mutans Opp system, and particularly the OppA protein, does not represent an important trait required for growth and colonization.
Opp系统是一种ATP结合盒式转运体，由细菌摄取寡肽所需的膜相关蛋白组成。在革兰氏阳性菌中，Opp系统，尤其是寡肽结合蛋白（OppA），已被证明参与细胞生理的不同方面，包括细胞间通讯和与宿主蛋白的结合。
在本研究中，我们开始研究变形链球菌（龋齿的主要病原体）的Opp系统。
在变形链球菌UA159菌株的基因组中鉴定出五个以单个操纵子形式组织的opp基因（oppABCDF）。氨基酸序列分析表明，变形链球菌OppA与无乳链球菌中发现的直系同源物密切相关。用抗OppA特异性血清孵育变形链球菌UA159细胞不会抑制聚苯乙烯平板上的生物膜形成。此外，在oppA或oppB基因上携带缺失的变形链球菌UA159衍生物在有无唾液的情况下，在聚苯乙烯孔中均未显示出明显的生长受损、对氨蝶呤敏感性增加或生物膜形成能力缺陷。值得注意的是，从龋齿过程中分离出的三株实验室菌株中只有两株以及七株临床菌株中的一株携带oppA基因拷贝并表达OppA蛋白。
总体而言，这些结果表明，与其他链球菌物种不同，变形链球菌的Opp系统，尤其是OppA蛋白，并不代表生长和定殖所需的重要特征。
