A NOVEL NUCLEIC-ACID HELICASE GENE IDENTIFIED BY PROMOTER TRAPPING INARABIDOPSIS

A gene encoding a predicted nucleic acid helicase was identified in Ar abidopsis thaliana by activation of a promoter trap. An in vivo transc riptional fusion between the helicase gene and a promoterless uidA (gu sA) gene was generated, which was expressed specifically in the tapetu m and vascular tissues. The tagged gene, designated HVT1 (Helicase in Vascular tissue and Tapetum), encodes a native transcript of approxima tely 4.4 kb, which is of very low abundance. The predicted HVT1 protei n, of 1291 amino acid residues, is homologous to the Drosophila MALELE SS, human RNA helicase A and bovine nuclear DNA helicase proteins, and represents the first identified member of a new subgroup within the m le group of the DEAH family. Low stringency genomic Southern blot anal ysis indicates that at least two structurally related genes exist in A rabidopsis. We suggest that the HVT1 protein may play a role in nuclei c acid unwinding in restricted cell types during both vegetative and r eproductive phases of the Arabidopsis life cycle.