Adaptation of the binding domain of Lactobacillus acidophilus S-layer protein as a molecular tag for affinity chromatography development

Abstract

The SLAP TAG is a novel molecular TAG derived from a protein domain present in the sequence of22 Lactobacillus acidophilus SlpA (SlpA284-444 ). Proteins from different biological sources, with different23 molecular weights or biochemical functions, can be fused in frame to the SLAP TAG and efficiently purified24 by the specific binding to a bacterial-derived chromatographic matrix named here Bio-Matrix (BM).25 Different binding and elution conditions were evaluated to set an optimized protocol for the SLAP TAG -26 based affinity chromatography (SAC). The binding equilibrium between SLAP TAG and BM was reached after27 a few minutes at 4 o C, being the apparent dissociation constant (K D ) of 4.3 μM, a value which is similar to28 different Kd determined for other S-layer proteins and their respective bacterial cell walls. A reporter29 protein was generated (H6-GFP-SLAP TAG ) to compare the efficiency of the SAC against a commercial30 system based on a Ni2+ -charged agarose matrix, observing no differences in the H6-GFP-SLAP TAG31 purification performance.