Our central goal is to create a nanopore sensor that can be tuned to specifically detect virtually any of these disease-related protein. The sensor is an engineered form of outer membrane protein G (OmpG) from E. coli. The loops that connect the strands of OmpG's ?-barrel are either appended with a ligand or lengthened with a recognition sequence to create the specific sensing elements. Our preliminary results demonstrate that the OmpG nanopore sensor is remarkably sensitive, able to distinguish variants within a mixture of antibodies that were all raised against the same hapten. To expand the utility of the sensor, we will explore the fundamental mechanisms that govern sensor-target interactions. Furthermore, the incorporation of new binding sites within OmpG's loops will proceed by two routes. The first is rational design, where we will incorporate known polypeptide sequences that recognize established targets. The second route takes advantage of OmpG's expression in the E. coli outer membrane. A randomized library of OmpG mutants will be selected for novel target affinity directly from the bacteria using a high- throughput screening and enrichment approach.
Detection of protein-based biomarkers is of great interest in the diagnosis and subsequent treatment of cancer or viral infection. This proposal outlines a new approach to create a nanopore sensor platform that can be rapidly tuned to detect virtually any specific protein.
