The respiratory pathogen moraxella catarrhalis binds to laminin via ubiquitous surface proteins A1 and A2.

Moraxella catarrhalis is one of the leading causes of exacerbations in chronic obstructive pulmonary disease (COPD). In the present article, we show that moraxella (n=15) binds to the major basement-membrane glycoprotein laminin, which is thickened in the airways of smokers. Using clinical strains of M. catarrhalis and their corresponding ubiquitous surface protein (Usp) A1/A2 mutants, we demonstrate that UspA1 and UspA2 are important for the laminin interaction. Binding assays with recombinant proteins demonstrated that the binding regions are localized within the N-terminal fragments, where both proteins form a globular head. Thus, UspA1/A2-dependent interactions with laminin might promote bacterial adhesion, particularly in smokers with COPD.