The viral V2 protein is one of the key factors that Tomato yellow leaf curl geminivirus (TYLCV), a major tomato pathogen worldwide, utilizes to combat the host defense. Besides suppressing the plant RNA silencing defense by targeting the host SGS3 component of the silencing machinery, V2 also interacts with the host CYP1 protein, a papain-like cysteine protease likely involved in hypersensitive response reactions. The biological effects of the V2-CYP1 interaction, however, remain unknown. We addressed this question by demonstrating that V2 inhibits the enzymatic activity of CYP1, but does not interfere with post-translational maturation of this protein. (C) 2015 Elsevier Inc. All rights reserved.