Affiliation:
1. Department of Plant Biology, University of Minnesota, St. Paul, Minnesota 55108
Abstract
ABSTRACT
The gene for ribonucleotide reductase from
Anabaena
sp. strain PCC 7120 was identified and expressed in
Escherichia coli
. This gene codes for a 1,172-amino-acid protein that contains a 407-amino-acid intein. The intein splices itself from the protein when it is expressed in
E. coli
, yielding an active ribonucleotide reductase of 765 residues. The mature enzyme was purified to homogeneity from
E. coli
extracts.
Anabaena
ribonucleotide reductase is a monomer with a molecular weight of approximately 88,000, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Superose 12 column chromatography. The enzyme reduces ribonucleotides at the triphosphate level and requires a divalent cation and a deoxyribonucleoside triphosphate effector. The enzyme is absolutely dependent on the addition of the cofactor, 5′-adenosylcobalamin. These properties are characteristic of the class II-type reductases. The cyanobacterial enzyme has limited sequence homology to other class II reductases; the greatest similarity (38%) is to the reductase from
Lactobacillus leichmannii
. In contrast, the
Anabaena
reductase shows over 90% sequence similarity to putative reductases found in genome sequences of other cyanobacteria, such as
Nostoc punctiforme, Synechococcus
sp. strain WH8102, and
Prochlorococcus marinus
MED4, suggesting that the cyanobacterial reductases form a closely related subset of the class II enzymes.
Publisher
American Society for Microbiology
Subject
Molecular Biology,Microbiology
Reference23 articles.
1. Isolation, sequence, and expression in Escherichia coli of an unusual thioredoxin gene from the cyanobacterium Anabaena sp. strain PCC 7120
2. Booker, S., S. Licht, J. Broderick, and J. A. Stubbe. 1994. Coenzyme B12-dependent ribonucleotide reductase: evidence for the participation of five cysteine residues in ribonucleotide reduction. Biochemistry33:12676-12685.
3. Copeland R. A. 1994. Methods for protein analysis. Chapman & Hall New York N.Y.
4. Eliasson, R., E. Pontis, A. Jordan, and P. Reichard. 1999. Allosteric control of three B12-dependent (class II) ribonucleotide reductases. Implications for the evolution of ribonucleotide reduction. J. Biol. Chem.274:7182-7189.
5. Eriksson, M., U. Uhlin, S. Ramaswamy, M. Ekberg, K. Regnström, B.-M. Sjöberg, and H. Eklund. 1997. Binding of allosteric effectors to ribonucleotide reductase system from Escherichia coli. J. Biol. Chem.267:25541-25547.
Cited by
19 articles.
订阅此论文施引文献
订阅此论文施引文献,注册后可以免费订阅5篇论文的施引文献,订阅后可以查看论文全部施引文献