1uca: Difference between revisions

Revision as of 11:01, 3 May 2008

Crystal structure of the Ribonuclease MC1 from bitter gourd seeds complexed with 2'-UMP

OverviewOverview

Ribonuclease MC1 (RNase MC1) isolated from seeds of bitter gourd (Momordica charantia) consists of 190 amino acids and is characterized by a preferential cleavage at the 5'-side of uridine. This uridine specificity distinguishes RNase MC1 from other enzymes belonging to the RNase T2 family. The three-dimensional structures of RNase MC1, in a complex with either 2'-UMP or 3'-UMP, were determined at 1.48 and 1.77 A resolutions, respectively. The side chains of Gln9 and Asn71 interact with O4 and N3, respectively, of the uracil base by hydrogen bondings. In addition, the uracil base is sandwiched by the hydrophobic side chains of Leu73 and Phe80. Compared with these amino acid residues and corresponding residues in RNases in the RNase T2 family, Gln9 and Phe80 are highly conserved in the RNases in T2 family, while Asn71 and Leu73 in RNase MC1 are variant in sequences. It is thus likely that interactions of the side chains of Asn71 and Leu73 with the uracil base are responsible for the absolute uridine specificity of RNase MC1. Site-directed mutagenesis experiments showed that replacement of Asn by Thr decreased both the catalytic efficiency and the binding affinity by 2.3- and 7.0-fold, respectively, and substitution of Leu73 for Ala predominantly decreased the binding affinity by 14. 5-fold, compared with findings in case of wild-type RNase MC1. It is thus demonstrated that Asn71 and Leu73 play an essential role in uridine preference for RNase MC1.

About this StructureAbout this Structure

1UCA is a Single protein structure of sequence from Momordica charantia. Full crystallographic information is available from OCA.

ReferenceReference

Crystal structures of the ribonuclease MC1 from bitter gourd seeds, complexed with 2'-UMP or 3'-UMP, reveal structural basis for uridine specificity., Suzuki A, Yao M, Tanaka I, Numata T, Kikukawa S, Yamasaki N, Kimura M, Biochem Biophys Res Commun. 2000 Aug 28;275(2):572-6. PMID:10964705 Page seeded by OCA on Sat May 3 11:01:51 2008

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OCA

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 '''Crystal structure of the Ribonuclease MC1 from bitter gourd seeds complexed with 2'-UMP'''
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 Crystal structures of the ribonuclease MC1 from bitter gourd seeds, complexed with 2'-UMP or 3'-UMP, reveal structural basis for uridine specificity., Suzuki A, Yao M, Tanaka I, Numata T, Kikukawa S, Yamasaki N, Kimura M, Biochem Biophys Res Commun. 2000 Aug 28;275(2):572-6. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/10964705 10964705]
 [[Category: Momordica charantia]]
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 [[Category: Kikukawa, S.]]
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 [[Category: Yamasaki, N.]]
 [[Category: Yao, M.]]
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+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May  3 11:01:51 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 00:08:21 2008''