Structure and properties of AB21, a novel Agaricus bisporus protein with structural relation to bacterial pore‐forming toxins

Abstract

We report the characterization of the dimeric protein AB21 from Agaricus bisporus, one of the most commonly and widely consumed mushrooms in the world. The protein shares no significant sequence similarity with any protein of known function, and it is the first characterized member of its protein family. The coding sequence of the ab21 gene was determined and the protein was expressed in E. coli in a recombinant form. We demonstrated a high thermal and pH stability of AB21 and proved the weak affinity of the protein to divalent ions of some transition metals (nickel, zinc, cadmium, and cobalt). The reported crystallographic structure exhibits an interesting rod-like helical bundle fold with structural similarity to bacterial toxins of the ClyA superfamily. By immunostaining, we demonstrated an abundance of AB21 in the fruiting bodies of A. bisporus.

Agaricus bisporus Crude Extract: Characterization and Analytical Application

“…The recently characterized AB21 protein A. bisporus was found in the ABE in significant quantities (Figure 1 A2). The reported crystallographic structure of AB21 protein exhibits a rod-like helical bundle fold with a structural similarity to bacterial toxins of the ClyA superfamily [35]. An abundance of AB21 in the fruiting bodies of A. bisporus was demonstrated by immunostaining.…”

Lectins from the Edible Mushroom Agaricus bisporus and Their Therapeutic Potentials

“…To date, only few proteins from A. bisporus have been investigated experimentally using an active fraction isolated from the fruiting bodies or as a recombinant protein. They are ABL [5], Abmb [20], PPO1 and PPO2 [21], PPO3 [4,22], PPO4 [23], and the most recently reported AB21 [24]. The latter is stable at a wide pH range (4.5-10.5), is thermostable, and has an affinity to transition metal ions, but displays no lectin activity.…”

“…The latter is stable at a wide pH range (4.5-10.5), is thermostable, and has an affinity to transition metal ions, but displays no lectin activity. The AB21 structure consists of a helix bundle organized as collagen-like [24]. The AB21 structure resembles the animal mannose-binding protein, but AB21 occurs as a dimer instead of trimer.…”