Determinants of IgA1 protease specificity
Tony Warren, Emily Kwan, Jenny Woof, Jiazhou Qiu, Andrew Plaut

Endoglucanse Cel6A and xylanase Xyn10A from Cellulomonas fimi each comprise a catalytic module and a carbohydrate-binding module connected by a proline-threonine linker. The sequences of the linkers are similar to that of the IgA1 hinge. IgA1 proteases cleave IgA1 at unique sites within the hinge. The proteases also cleave within the linkers of Cel6A qnd Xyn10A but not at unique sites. If the proline-threonine linkers of Cel6A qnd Xyn10A are substituted for the normal hinge sequence of IgA1, the modified IgA1s are still cleaved by IgA1 proteases, but not at unique sites. These results will be discussed within the context of determinants of the specificity of IgA1 proteases.