Lil3 dimerization and chlorophyll binding in Arabidopsis thaliana

The two-helix light harvesting like (Lil) protein Lil3 belongs to the family of chlorophyll binding light harvesting proteins of photosynthetic membranes. A function in tetrapyrrol synthesis and stabilization of geranylgeraniol reductase has been shown. Lil proteins contain the chlorophyll a/b-binding motif; however, binding of chlorophyll has not been demonstrated. We find that Lil3.2 from Arabidopsis thaliana forms heterodimers with Lil3.1 and binds chlorophyll. Lil3.2 heterodimerization (25 +/- 7.8 nM) is favored relative to homodimerization (431 +/- 59 nM). Interaction of Lil3.2 with chlorophyll a (231 +/- 49 nM) suggests that heterodimerization precedes binding of chlorophyll in Arabidopsis thatiana. (C) 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.