Extended N-terminal helix domains selectively decrease enzymatic activity in Sortase A

Class A Sortase enzymes covalently attach virulence factors to the cell wall of gram-positive bacteria. The mechanism by which this happens is thought to be mainly performed by the catalytic domain of the Sortase. However, a helical region on the N-terminus of the catalytic domain may be affecting the function of the enzyme as well. To investigate this region, extended catalytic domains were designed to include different amounts of the N-terminal helix. Results found that Sortase enzymes with these extended domains selectively showed lower enzymatic activity in class A Sortase for both staphylococcus aureus and streptococcus pyogenes, depending on the substrate. This opens the door for further studies on this region of Sortase.