NUCLEOTIDE-SEQUENCE OF A 1446 BASE-PAIR SALI FRAGMENT AND STRUCTURE OF A NOVEL EARLY GENE OF LEUCANIA-SEPERATA NUCLEAR POLYHEDROSIS-VIRUS

A 1446 bp Sa1I fragment of LsNPV was sequenced by the silver staining method, and two large open reading frames (ORFs, ORF1 and ORF2) were f ound, both contain typical characteristics of the 5' regulatory elemen ts of baculovirus early genes. ORF1 is 345 bp long with the capacity t o encode a putative protein of 114 amino acid residues with MW about 1 3 kDa and was designated p13 gene, ORF2 comprises 248 bp from the 3' e nd of the fragment. In the untranslated region (UTR) of ORF1, a 33 bp mini cistron (ORF3), a core recognition sequence (CGTCG) for many bHLH zip transcription factors and a late promoter sequence TTAAG are prese nt. In the UTR of ORF2, two host transcription factor binding elements (CACGTG and GATA motif) and two CGT motifs were found. Some regular l eucine zipper-like structures, designated leucine trans-conformation s tructure and LVT repeat, were found near the N-terminus and the middle of p13 protein. The leucine trans-conformation structure that is near the N-terminus consists of 4 leucines and 7 other amino acids between every two leucines, and every leucine is located at a conformation sh ift point of the predicted secondary structure of the p 13 protein. In LVT repeat, L-6aa-V-6aa-T-6aa is repeated once. The functions of thos e structures remain unclear, and the two ORFs, not found in the genome of Autographa californica nuclear polyhedrosis virus, are possibly tw o new genes.