Biosensing MAPs as "roadblocks": kinesin-based functional analysis of tau protein isoforms and mutants using suspended microtubules (sMTs).

Abstract

The concept of a reconstructed microtubule kinesin-based transport system was originally introduced for studies of underlying biophysical mechanisms of intracellular transport and its potential applications in bioengineering at micro- and nanoscale levels. However, several technically challenging shortcomings prohibit its use in practical applications. One of them is the propensity of microtubules to bind various protein molecules creating "roadblocks" for kinesin molecule movement and subsequently preventing efficient delivery of the molecular cargo. The interruption in kinesin movement strictly depends on the specific type of "roadblock", i.e. the microtubule associated protein (MAP). Therefore, we propose to use the "roadblock" effect as a molecular sensor that may be used for functional characterization of particular MAPs with respect to their role in MT-based transport and associated pathologies, such as neurodegeneration. Here, we applied a kinesin-based assay using a suspended MT design (sMT assay) to functionally characterize known MAP tau protein isoforms and common mutations found in familial frontotemporal dementia (FTD). The proposed sMT assay is compatible with an on-chip format and may be used for the routine characterization of MT associated molecules applicable to diagnostics and translational research.