scholarly journals New crystal forms of the small subunit of ribonucleotide reductase from Escherichia coli

FEBS Letters ◽  
1989 ◽  
Vol 258 (2) ◽  
pp. 251-254 ◽  
Author(s):  
Par Nordlund ◽  
Ulla Uhlin ◽  
Christina Westergren ◽  
Thorleif Joelsen ◽  
Britt-Marie Sjöberg ◽  
...  
1993 ◽  
Vol 290 (3) ◽  
pp. 807-810 ◽  
Author(s):  
M Atta ◽  
N Lamarche ◽  
J P Battioni ◽  
B Massie ◽  
Y Langelier ◽  
...  

Protein R2, the small subunit of ribonucleotide reductase, contains a diferric centre and a tyrosyl radical absolutely required for enzyme activity. The reduction of the tyrosyl radical and the mobilization of the iron centre result in the inhibition of the enzyme and thus of DNA synthesis. The chemical reactivity of the iron-radical centre of Escherichia coli and herpes simplex virus has been studied by u.v.-visible and e.p.r. spectroscopies. The tyrosyl radical is efficiently scavenged by hydroxamic acids and phenols during reactions controlled by steric hindrance and hydrophobic interactions. The reaction with o-disubstituted phenols yields the corresponding diphenoquinones. The reactivity of the bacterial radical greatly contrasts with that of the viral radical, and the iron centre in herpes-simplex-virus R2 is much more labile than that in E. coli R2, as shown from the facile mobilization of iron by chelators such as catechol. These results suggest that the active sites of the two enzymes are significantly different and might be useful for designing new antiviral agents.


Biochemistry ◽  
1989 ◽  
Vol 28 (6) ◽  
pp. 2618-2625 ◽  
Author(s):  
Margareta Sahlin ◽  
Astrid Graeslund ◽  
Leif Petersson ◽  
Anders Ehrenberg ◽  
Britt Marie Sjoeberg

Author(s):  
G. Stöffler ◽  
R.W. Bald ◽  
J. Dieckhoff ◽  
H. Eckhard ◽  
R. Lührmann ◽  
...  

A central step towards an understanding of the structure and function of the Escherichia coli ribosome, a large multicomponent assembly, is the elucidation of the spatial arrangement of its 54 proteins and its three rRNA molecules. The structural organization of ribosomal components has been investigated by a number of experimental approaches. Specific antibodies directed against each of the 54 ribosomal proteins of Escherichia coli have been performed to examine antibody-subunit complexes by electron microscopy. The position of the bound antibody, specific for a particular protein, can be determined; it indicates the location of the corresponding protein on the ribosomal surface.The three-dimensional distribution of each of the 21 small subunit proteins on the ribosomal surface has been determined by immuno electron microscopy: the 21 proteins have been found exposed with altogether 43 antibody binding sites. Each one of 12 proteins showed antibody binding at remote positions on the subunit surface, indicating highly extended conformations of the proteins concerned within the 30S ribosomal subunit; the remaining proteins are, however, not necessarily globular in shape (Fig. 1).


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