Lee S F, Davey L
1 Department of Microbiology and Immunology, Dalhousie University, Halifax, NS, Canada.
2 Canadian Center for Vaccinology, Dalhousie University and the IWK Health Centre, Halifax, NS, Canada.
J Dent Res. 2017 Dec;96(13):1465-1473. doi: 10.1177/0022034517725059. Epub 2017 Aug 10.
Disulfide bonds are a common posttranslational modification that contributes to the folding and stability of extracytoplasmic proteins. Almost all organisms, from eukaryotes to prokaryotes, have evolved enzymes to make and break these bonds. Accurate and efficient disulfide bond formation can be vital for protein function; therefore, the enzymes that catalyze disulfide bond formation are involved in multiple biological processes. Recent advances clearly show that oral bacteria also have the ability to from disulfide bonds, and this ability has an effect on a range of dental plaque-related phenotypes. In the gram-positive Streptococcus gordonii, the ability to form disulfide bonds affected autolysis, extracellular DNA release, biofilm formation, genetic competence, and bacteriocin production. In Actinomyces oris, disulfide bond formation is needed for pilus assembly, coaggregation, and biofilm formation. In other gram-positive bacteria, such as Enterococcus faecalis, disulfide bonds are formed in secreted bacteriocins and required for activity. In these oral bacteria, the enzymes that catalyze the disulfide bonds are quite diverse and share little sequence homology, but all contain a CXXC catalytic active site motif and a conserved C-terminal cis-proline, signature features of a thiol-disulfide oxidoreductase. Emerging evidence also indicates that gram-negative oral bacteria, such as Porphyromonas gingivalis and Tannerella forsythia, use disulfide bonds to stabilize their outer membrane porin proteins. Bioinformatic screens reveal that these gram-negative bacteria carry genes coding for thiol-disulfide oxidoreductases in their genomes. In conclusion, disulfide bond formation in oral bacteria is an emerging field, and the ability to form disulfide bonds plays an important role in dental plaque formation and fitness for the bacteria.
二硫键是一种常见的翻译后修饰，有助于胞外蛋白的折叠和稳定性。几乎所有生物，从真核生物到原核生物，都进化出了形成和断裂这些键的酶。准确而高效的二硫键形成对于蛋白质功能至关重要；因此，催化二硫键形成的酶参与多种生物学过程。最近的进展清楚地表明，口腔细菌也有形成二硫键的能力，并且这种能力对一系列与牙菌斑相关的表型有影响。在革兰氏阳性的戈登链球菌中，形成二硫键的能力影响自溶、细胞外DNA释放、生物膜形成、遗传感受态和细菌素产生。在口腔放线菌中，菌毛组装、共聚和生物膜形成需要二硫键形成。在其他革兰氏阳性细菌，如粪肠球菌中，分泌的细菌素中形成二硫键且活性需要二硫键。在这些口腔细菌中，催化二硫键的酶种类繁多且序列同源性低，但都含有CXXC催化活性位点基序和保守的C端顺式脯氨酸，这是硫醇-二硫键氧化还原酶的标志性特征。新出现的证据还表明，革兰氏阴性口腔细菌，如牙龈卟啉单胞菌和福赛坦氏菌，利用二硫键来稳定其外膜孔蛋白。生物信息学筛选显示，这些革兰氏阴性细菌在其基因组中携带编码硫醇-二硫键氧化还原酶的基因。总之，口腔细菌中二硫键形成是一个新兴领域，形成二硫键的能力在牙菌斑形成和细菌适应性方面发挥着重要作用。
