Nucleotide Sequence of a Gene Encoding a 58.5-Kilodalton Barley Dehydrin That Lacks a Serine Tract

Dehydrins, also known as the late embryogenesis abundant (LEA) D-11 family of proteins (Close et al., 1993, and refs. therein), generally accumulate in plants in response to water deficit, embryo desiccation, cold temperature, reduction in externa1 osmotic potential, or application of ABA. Over 40 examples of deduced amino acid sequences of higher plant dehydrins have been published to date, and there is immunological evidence of related proteins in organisms as distant from higher plants as cyanobacteria (Close and Lammers, 1993). Known members of this family of proteins are characterized by the presence of highly conserved repeating motifs including the Lys-rich 15amino acid consensus EKKGIMDKIKEKLPG, which is always located near the carboxy terminus (the lone exception being cotton LEA D-11). A related but slightly less conserved consensus sequence is usually repeated at least once and up to 10 additional times in published examples of plant dehydrins. Dehydrins can be divided into two main classes, those containing approximately nine consecutive Ser residues and those without this Ser tract. The Ser residues in this tract can be phosphorylated, and it has been proposed that phosphorylation of Ser's is related to the binding of nuclear localization signal peptides (Goday et al., 1994). Dehydrins have a nucleocytoplasmic location (Asghar et al., 1994; Goday et al., 1994). The majority of dehydrins identified to date fall into the class that contains the Ser tract, and the minority fall into the latter class, without the Ser tract. Those in the former class usually contain two or three Lys-rich consensus blocks. Dehydrins in the latter class usually contain six or more consensus blocks. There are exceptions to these generalizations, and each class can be subdivided further based on intervening amino acid sequences located between the consensus blocks. Examples of dehydrins that lack a Ser tract include spinach CAP85 (61.5 kD with 11 repeats) (Neven et al., 1993), wheat WCS120 (39.0 kD with 6 repeats) (Houde et al., 1992)' and wheat COR39 (39.1 kD