CDNA cloning and deduced amino acid sequences of three storage proteins in the common cutworm, Spodoptera litura (Lepidoptera: Noctuidae).

Abstract

Three storage proteins, hexamerins of 80-90 kDa subunits, have been purified and characterized from the common cutworm, Spodoptera litura. We have cloned the cDNAs of these storage proteins by immunoscreening and rapid amplification of cDNA ends (RACE). The deduced amino acid sequence of SL-1, a basic protein containing 7.7% methionine showed 82.3 and 68.4% identities to the Trichoplusia ni basic juvenile hormone-suppressible storage protein (8.4% methionine) and to the Bombyx mori methionine-rich storage protein (11.8% methionine), respectively. The amino acid sequences of α and β subunits with ca 4% methionine of SL-2, another basic protein, were 84% identical to that of T. ni basic juvenile hormone-suppressible storage protein with moderate methionine content (5.3%), but showed only 45% identity to SL-1. SL-3, an arylphorin was very similar (54-63% identity) to known other arylphorins, but differed considerably (31-35% identity) from SL-1 and SL-2 in their amino acid alignments. The most parsimonious tree obtained by systematic analyses of the sequence alignments of 16 lepidopteran storage proteins demonstrated that three storage proteins of S. litura are clustered into three sister groups, although they share extensive similarities throughout the alignment.