CLONING AND EXPRESSION OF A NEW CDNA FROM MONOCOTYLEDONOUS PLANTS CODING FOR A DIADENOSINE 5',5'''-P-1,P-4-TETRAPHOSPHATE HYDROLASE FROM BARLEY (HORDEUM-VULGARE)

From a cDNA library generated from mRNA of white leaf tissues of the r ibosome-deficient mutant 'albostrians' of barley (Hordeum vulgare cv. Haisa) a cDNA mas isolated carrying 54.2% identity to a recently publi shed cDNA which codes for the diadenosine-5',5'''-P-1,P-4-tetraphospha te (Ap(4)A) hydrolase of Lupinus angustifolius (Maksel et al, (1998) B iochem, J, 329, 313-319), and 69% identity to four partial peptide seq uences of Ap(4)A hydrolase of tomato. Overexpression in Escherichia co li revealed a protein of about 19 kDa, which exhibited Ap(4)A hydrolas e activity and cross-reactivity with an antibody raised against a puri fied tomato Ap(4)A hydrolase (Feussner et al, (1996) Z, Naturforsch, 5 1c, 477-486), Expression studies showed an mRNA accumulation in all or gans of a barley seedling, Possible functions of Ap(4)A hydrolase in p lants will be discussed. (C) 1998 Federation of European Biochemical S ocieties.