Extreme divergence of a novel wheat thionin generated by a mutational burst specifically affecting the mature protein domain of the precursor

CASTAGNARO, ATILIO; MARAÑA, CARMEN; CARBONERO, PILAR; GARCÍA-OLMEDO, FRANCISCO

JOURNAL OF MOLECULAR BIOLOGY

ACADEMIC PRESS LTD-ELSEVIER SCIENCE LTD

Año: 1992 vol. 224 p. 1003 - 1009

0022-2836

A new type of neutral thionin (type V), specifically expressed in developing wheat endosperm, has been found to be encoded by a set of single-copy genes located in the long arms of chromosomes 1A, 1B and 1D, within less than 10,000 base-pairs of those corresponding to the highly basic type-I thionins. Divergence between types I and V has occurred through a process of accelerated evolution that has affected the amino acid sequence of the mature thionin but not the precursor domains corresponding to the N-terminal signal peptide and the long C-terminal acidic peptide. This process involved a deletion and a non-synonymous nucleotide substitution rate equal to the synonymous rate in the thionin sequence. © 1992.