Diamond x-rays uncover structure of tooth decay enzymes
4 May 2011
Tooth decay can occur when dental plaque - a 'biofilm' - is formed by a large and sticky glucose polymer called glucan. The glucan biofilm contains bacteria and food debris and forms on the surface of the tooth. As they grow, the bacteria secrete acids, which break down the tooth's hard enamel on the surface.
Together with researchers from the Photon Factory in Tsukuba city, Japan, scientists at Diamond have provided structural information on how the enzyme GTF-SI forms glucan. The research is published in the 'Journal of Molecular Biology'.
"We have been able to solve not only the structure of the enzyme alone but also its structure when bound to an existing inhibitor," says Sohei Ito from the University of Shizuoka in Japan, the lead researcher on the project. "Several inhibitors that prevent this type of enzyme forming glucan have been identified but to date there has been little structural information available.
"With the data we collected at Diamond and the Photon Factory, we now have a better understanding of how the enzyme functions and how it can be stopped. This structural information should be useful in the design of novel inhibitors that will prevent the biofilm formation… These novel inhibitors could be incorporated into toothpaste and mouthwash, making them more effective at preventing tooth decay."
According to the World Oral Health Report 2003, tooth decay, or dental caries, is a major health problem in most industrialised countries, affecting between six and nine in every ten schoolchildren and the vast majority of adults. If left untreated for a long period of time, it can result in pain and tooth loss and lead to gum disease and halitosis (bad breath). Novel inhibitors create the potential to reduce the risk of tooth decay by preventing the formation of dental plaque.
Principal Beamline Scientist at Diamond, Professor Thomas Sorensen, says: "Knowing the 3D structure of the enzyme is like knowing the shape of a lock you need to find a key for - it makes it much easier to find the right key that will fit. In this case, the inhibitor acts like the key, fitting into the lock in just the right way so that it can do its job."
Image: Structure of glucansucrase from the dental caries pathogen Streptococcus mutans. Credit: Sohei Ito, University of Shizuoka, Japan.
Reference
Ito K et al. Crystal structure of glucansucrase from the dental caries pathogen Streptococcus mutans. J Mol Biol 2011; 408(2): 177-86
