The Zinc-Finger Thylakoid-Membrane Protein FIP Is Involved With Abiotic Stress Response in Arabidopsis thaliana

Abstract

Many plant genes have their expression modulated by stress conditions. Here, we used <i>Arabidopsis</i> FtsH5 protease, which expression is regulated by light stress, as bait in a yeast two-hybrid screen to search for new proteins involved in the stress response. As a result, we found FIP (FtsH5 Interacting Protein), which possesses an amino proximal cleavable transit peptide, a hydrophobic membrane-anchoring region, and a carboxyl proximal C₄-type zinc-finger domain. <i>In vivo</i> experiments using FIP fused to green fluorescent protein (GFP) showed a plastid localization. This finding was corroborated by chloroplast import assays that showed FIP inserted in the thylakoid membrane. <i>FIP</i> expression was down-regulated in plants exposed to high light intensity, oxidative, salt, and osmotic stresses, whereas mutant plants expressing low levels of <i>FIP</i> were more tolerant to these abiotic stresses. Our data shows a new thylakoid-membrane protein involved with abiotic stress response in <i>Arabidopsis thaliana</i>.