3D Blockage Mapping for Identifying Familial Point Mutations in Single Amyloid‐β Peptides with a Nanopore

Abstract

Accurate discrimination of amyloid-β (Aβ) peptides containing familial point mutations would advance the knowledge of their roles in early-onset Alzheimer's disease. Herein, we simultaneously identified the mutant A21G, E22G, E22Q, and the wild-type (WT) Aβ 18-26 peptides with aerolysin nanopore using a 3D blockage mapping strategy. The standard deviation of current blockade fluctuations (σ b ) was proposed as a new supplement to current blockage (I b /I 0 ) and duration time (t D ) to profile the blockage characteristics of single molecules. Although the WT and A21G Aβ 18-26 are indistinguishable in a traditional I b /I 0 -t D 2D description, ~87 % of the blockade events can be accurately classified with half reduction of false identification using a combination of I b /I 0 , t D, and σ b . This work offers an easy and reliable strategy to promote nanopore sensitivity of peptide mutants, leading to a more precise analysis of pathogenic mutations for developing effective diagnosis and treatment.

Engineering Biological Nanopore Approaches toward Protein Sequencing

“…The task of developing a uniform modification method for different AAs is further complicated by the need to incorporate target AAs into predesigned, charged peptide chains while preserving the self-identity of the AAs. Furthermore, due to the diversity of AAs, current blockage measurements commonly used for analyte identification are insufficient for protein sequencing; more parameters from current traces, such as standard variation of the current, , peak shape, and the frequency in the current recording need to be considered. ,, Evidently, achieving nanopore protein sequencing through AA discrimination remains an ongoing endeavor that requires a multidisciplinary approach and a systematic engineering solutions.…”

Narrowing Signal Distribution by Adamantane Derivatization for Amino Acid Identification Using an α-Hemolysin Nanopore

“…Recent studies have shown that ionic current blockade fluctuations (σ b ), indicating nanopore current “noise”, can distinguish analyte species differently from the traditional blockade and dwell time measurements. ,, This “noise” varies with each analyte, reflecting diverse interaction dynamics in the nanopore sensing space. ,− We analyzed the standard deviation of these fluctuations in individual events, presenting them as distribution histograms with Gaussian fitting (Figure a-c, right panel and Figure S3) for better discrimination of the ALAAs. With such additional information, all AAs in each group were successfully distinguished despite minor overlaps of the distributions.…”