Assembles with botulinum neurotoxin type E (BoNT/E) and protects it against pH-mediated inactivation or protease activity at pH 2.6 (the pH of the animal gastrointestinal tract) but not at pH 6.0 (By similarity). The non-toxic component is necessary to maintain toxicity. Forms a highly interlocked heterodimer with botulinum neurotoxin type E at pH 6.0 but not at pH 7.5 (By similarity). Belongs to the botulism non-toxic nonhemagglutinin family.