Cloning of lipopolysaccharide binding protein genes of Lotus japonicus

Abstract

Lipopolysaccharides (LPS) are structural components of the outer membrane of Gram-negative bacteria and LPS of pathogen induce the plant resistant. LPS are also related in the establishment of symbiosis between legume and rhizobium. Thus, the elucidation of the LPS recognition system is important for understanding the plant-bacteria interaction. However, LPS recognition system is not clear in plants. In animal, the LPS receptor and LPS binding protein (LBP) have been identified. Refering LPS recognition systems of animal, we tried to clone LBP genes of Lotus japonicus. As the result of BLAST in the genome library of L. japonicus, there are four high similarity regions with human LBP. We cloned three genes derived from these four regions by RT-PCR and referred to as LjLBP1, 2, 3. Similarity of these LjLBPs to human LBP is about 40% and expressed protein correspond to N-terminal domain of LjLBP1 showed the LPS binding activity.