Sequence determinants of amyloid fibril formation

The establishment of rules that link sequence and amyloid feature is critical for our understanding of misfolding diseases. To this end, we have performed a saturation mutagenesis analysis on the de novo-designed amyloid peptide STVIIE (1). The positional scanning mutagenesis has revealed that there is a position dependence on mutation of amyloid fibril formation and that both very tolerant and restrictive positions to mutation can be found within an amyloid sequence. In this system, mutations that accelerate β-sheet polymerization do not always lead to an increase of amyloid products. On the contrary, abundant fibrils are typically found for mutants that polymerize slowly. From these experiments, we have extracted a sequence pattern to identify amyloidogenic stretches in proteins. The pattern has been validated experimentally. In silico sequence scanning of amyloid proteins also supports the pattern. Analysis of protein databases has shown that highly amyloidogenic sequences matching the pattern are less frequent in proteins than innocuous amino acid combinations and that, if present, they are surrounded by amino acids that disrupt their aggregating capability (amyloid breakers). This study provides the potential for a proteome-wide scanning to detect fibril-forming regions in proteins, from which molecules can be designed to prevent and/or disrupt this process

Nanosensors based detection of foodborne pathogens

Contaminated food cause by pathogens is one of the main reasons incidences of human diseases cases all around the world. Typically, most foodborne contaminants caused by bacteria, parasites and virus that have a major economic impact. It is important to restrain them, thus early detection system is very crucial. Several methods have been explored for the detection and identification of these microorganisms in food samples. However, some of these methods are involves complicated sample pre-treatment, laborious, time-consuming and are not suitable for on-site applications. Therefore, it is very important to develop rapid, sensitive, selective and more approachable detection methods. Recently, biosensors have been explored as alternative approach method and considered as one of most rapid and on-site applicable methods. Advancements in nanotechnology have provided biosensor with novel architecture by using nanoscaled materials and structures for enhance the biosensing performance. This article highlights the significant progress of nanosensor based on electrochemical and optical, and other types of nanosensors with the focus on the foodborne pathogen detection