Open AccessAmino acid sequence of an extracellular, phosphate‐starvation‐induced ribonuclease from cultured tomato ( Lycopersicon esculentum ) cells
Author(s) -
JOST Wolfgang,
BAK Henk,
GLUND Konrad,
TERPSTRA Peter,
BEINTEMA Jaap J.
Publication year - 1991
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1991.tb15978.x
Subject(s) - ribonuclease , rnase p , biology , s tag , biochemistry , lycopersicon , peptide sequence , amino acid , pentapeptide repeat , microbiology and biotechnology , isoelectric point , molecular mass , protein primary structure , complementary dna , enzyme , gene , rna , peptide , botany
The primary structure of an extracellular ribonuclease (RNase LE) from P i ‐depleted media of cultured cells of Lycopersicon esculentum L. cv. Lukullus has been determined. This was carried out by analysis of peptides isolated after enzymatic and chemical cleavage of the reduced and S ‐ethylpyridylated protein. RNase LE consists of 205 amino acid residues and has a molecular mass of 22666 Da and an isoelectric point of 4.24. The enzyme contains 10 half‐cystines. There are no potential N ‐glycosylation sites in the sequence. The sequence of RNase LE is homologous with those of self‐incompatibility proteins of several higher plant species and with those of a number of fungal RNases. The sequence similarity with the family of self‐incompatility proteins is greater than with the fungal RNases, suggesting that the self‐incompatibility proteins arose from ancestral RNase by gene duplication after the divergence of higher plants and fungi. Two pentapeptide sequences, i.e. HGLWP and KHGTC (or KHGSC), are present at identical positions in all the aligned proteins, suggesting that they contribute to the active site.