The ribonuclease MC1 (RNase MC1) from seeds of bitter gourd (Momordica charantia) consists of 190 amino acid residues with four disulfide bridges and belongs to the RNase T2 family, including fungal RNases typified by RNase Rh from Rhizopus niveus and RNase T2 from Aspergillus oryzae. The crystal structure of RNase MC1 has been determined at 1.75 A resolution with an R-factor of 19.7% using the single isomorphous replacement method. RNase MC1 structurally belongs to the (α+β) class of proteins, having ten helices (six α-helices and four 310-helices) and eight β-strands. When the structures of RNase MC1 and RNase Rh are superposed, the close agreement between the α-carbon positions for the total structure is obvious: the root mean square deviations calculated only for structurally related 151 α-carbon atoms of RNase MC1 and RNase Rh molecules was 1.76 A. Furthermore, the conformation of the catalytic residues His-46, Glu-105, and His-109 in RNase Rh can be easily superposed with that of the possible catalytic residues His-34, Glu-84, and His-88 in RNase MC1. This observation strongly indicates that RNase MC1 from a plant origin catalyzes RNA degradation in a similar manner as fungal RNases. Copyright (C) 1999 Elsevier Science B.V.
|Number of pages||8|
|Journal||Biochimica et Biophysica Acta - Protein Structure and Molecular Enzymology|
|Publication status||Published - Aug 17 1999|
All Science Journal Classification (ASJC) codes
- Structural Biology
- Molecular Biology