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Hints on the evolutionary design of a dimeric RNase with special bioactions
Author(s) -
Donato Alberto Di,
Cafaro Valeria,
Romeo Ivana,
D'Alessio Giuseppe
Publication year - 1995
Publication title -
protein science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.353
H-Index - 175
eISSN - 1469-896X
pISSN - 0961-8368
DOI - 10.1002/pro.5560040804
Subject(s) - rnase p , rnase ph , mutant , rnase mrp , rnase h , cleavage (geology) , stereochemistry , chemistry , biochemistry , biology , genetics , gene , rna , fracture (geology) , paleontology
Residues P19, L28, C31, and C32 have been implicated (Di Donato A, Cafaro V, D'Alessio G, 1994, J Biol Chem 269 :17394–17396; Mazzarella L, Vitagliano L, Zagari A, 1995, Proc Natl Acad Sci USA : forthcoming) with key roles in determining the dimeric structure and the N‐terminal domain swapping of seminal RNase. In an attempt to have a clearer understanding of the structural and functional significance of these residues in seminal RNase, a series of mutants of pancreatic RNase A was constructed in which one or more of the four residues were introduced into RNase A. The RNase mutants were examined for: (1) the ability to form dimers; (2) the capacity to exchange their N‐terminal domains; (3) resistance to selective cleavage by subtilisin; and (4) antitumor activity. The experiments demonstrated that: (1) the presence of intersubunit disulfides is both necessary and sufficient for engendering a stably dimeric RNase; (2) all four residues play a role in determining the exchange of N‐teminal domains; (3) the exchange is the molecular basis for the RNase antitumor action; and (4) this exchange is not a prerequisite in an evolutionary mechanism for the generation of dimeric RNases.