Identification and cloning of odorant binding proteins from the scarab beetle Phyllopertha diversa

We have identified, cloned, and characterized two odorant binding proteins from the pale brown chafer, Phyllopertha diversa. One of the proteins (OEP1 , 116 amino acids long) showed high amino acid identity (>90%) to two previ ously identified PBPs from scarab beetles. The second protein (OBP2) showed limited sequence similarity to lepidopteran and dipteran OBPs, but contain ed only 133 amino acids. Both proteins showed the occurrence of six highly conserved cysteines; electrospray mass spectral data suggested they are all bound in three disulfide bonds. During purification, OBP2 separated into s everal isoforms; N-terminal amino acid sequencing and electrospray ionizati on mass spectrometry demonstrated that they are different conformations of the same protein. In the native gel electrophoresis binding experiments, no ne of the OBPs bound 1,3-dimethyl-2,4-(1H,3H)-quinazolinedione but differen t isoforms showed different binding affinities for (R)-japonilure, a pherom one from related scarab beetles, and bombykol, the pheromone from the silkw orm moth, Bombyx mori. OBP1 aIsobound (R)-japonilure. (C) 1999 Academic Pre ss.