3DHZ

Apo (iron free) structure of C. ammoniagenes R2 protein

Summary for 3DHZ

• Entry DOI: 10.2210/pdb3dhz/pdb
• Related: 1KGN 1KGO 1KGP 1OQU
• Descriptor: Ribonucleotide reductase subunit R2F, FE (II) ION (3 entities in total)
• Functional Keywords: metal free, ribonucleotide reductase, hydrogen bond, metal binding protein
• Biological source: Corynebacterium ammoniagenes (Brevibacterium ammoniagenes)
• Total number of polymer chains: 2
• Total formula weight: 76141.43

Authors

Hogbom, M.,Nordlund, P. (deposition date: 2008-06-19, release date: 2008-07-01, Last modification date: 2024-02-21)

Primary citation

Andersson, M.E.,Hogbom, M.,Rinaldo-Matthis, A.,Blodig, W.,Liang, Y.,Persson, B.O.,Sjoberg, B.M.,Su, X.D.,Nordlund, P.
Structural and mutational studies of the carboxylate cluster in Iron-free Ribonucleotide Reductase R2.
Biochemistry, 43:7966-7972, 2004

PubMed Abstract: The R2 protein of ribonucleotide reductase features a di-iron site deeply buried in the protein interior. The apo form of the R2 protein has an unusual clustering of carboxylate side chains at the empty metal-binding site. In a previous study, it was found that the loss of the four positive charge equivalents of the diferrous site in the apo protein appeared to be compensated for by the protonation of two histidine and two carboxylate side chains. We have studied the consequences of removing and introducing charged residues on the local hydrogen-bonding pattern in the region of the carboxylate cluster of Corynebacterium ammoniagenes and Escherichia coli protein R2 using site-directed mutagenesis and X-ray crystallography. The structures of the metal-free forms of wild-type C. ammoniagenes R2 and the mutant E. coli proteins D84N, S114D, E115A, H118A, and E238A have been determined and their hydrogen bonding and protonation states have been structurally assigned as far as possible. Significant alterations to the hydrogen-bonding patterns, protonation states, and hydration is observed for all mutant E. coli apo proteins as compared to wild-type apo R2. Further structural variations are revealed by the wild-type apo C. ammoniagenes R2 structure. The protonation and hydration effects seen in the carboxylate cluster appear to be due to two major factors: conservation of the overall charge of the site and the requirement of electrostatic shielding of clustered carboxylate residues. Very short hydrogen-bonding distances between some protonated carboxylate pairs are indicative of low-barrier hydrogen bonding.

PubMed: 15196041
DOI: 10.1021/bi036088l

Experimental method

X-RAY DIFFRACTION (1.63 Å)