2JB0

CRYSTAL STRUCTURE OF THE MUTANT H573A OF THE NUCLEASE DOMAIN OF COLE7 IN COMPLEX WITH IM7

Summary for 2JB0

• Entry DOI: 10.2210/pdb2jb0/pdb
• Related: 1AYI 1CEI 1M08 1MZ8 1PT3 1UJZ 1UNK 1ZNS 1ZNV 2AXC 2ERH 2IVH 2JAZ 7CEI
• Descriptor: COLICIN E7 IMMUNITY PROTEIN, COLICIN E7, ZINC ION, ... (4 entities in total)
• Functional Keywords: hydrolase/inhibitor, hydrolase-inhibitor complex, zinc, toxin, plasmid, nuclease, hydrolase, antibiotic, h-n-h motif, bacteriocin, endonuclease, metal-binding, antimicrobial, dna hydrolysis, bacteriocin immunity, his metal finger motif
• Biological source: ESCHERICHIA COLI; More
• Total number of polymer chains: 2
• Total formula weight: 24967.41

Authors

Huang, H.,Yuan, H.S. (deposition date: 2006-12-01, release date: 2007-04-03, Last modification date: 2023-12-13)

Primary citation

Huang, H.,Yuan, H.S.
The Conserved Asparagine in the Hnh Motif Serves an Important Structural Role in Metal Finger Endonucleases.
J.Mol.Biol., 368:812-, 2007

PubMed Abstract: The HNH motif is a small nucleic acid binding and cleavage module, widespread in metal finger endonucleases in all life kingdoms. Here we studied a non-specific endonuclease, the nuclease domain of ColE7 (N-ColE7), to decipher the role of the conserved asparagine and histidine residues in the HNH motif. We found, using fluorescence resonance energy transfer (FRET) assays, that the DNA hydrolysis activity of H545 N-ColE7 mutants was completely abolished while activities of N560 and H573 mutants varied from 6.9% to 83.2% of the wild-type activity. The crystal structures of three N-ColE7 mutants in complex with the inhibitor Im7, N560A-Im7, N560D-Im7 and H573A-Im7, were determined at a resolution of 1.9 A to 2.2 A. H573 is responsible for metal ion binding in the wild-type protein, as the zinc ion is still partially associated in the structure of H573A, suggesting that H573 plays a supportive role in metal binding. Both N560A and N560D contain a disordered loop in the HNH motif due to the disruption of the hydrogen bond network surrounding the side-chain of residue 560, and as a result, the imidazole ring of the general base residue H545 is tilted slightly and the scissile phosphate is shifted, leading to the large reductions in hydrolysis activities. These results suggest that the highly conserved asparagine in the HNH motif, in general, plays a structural role in constraining the loop in the metal finger structure and keeping the general base histidine and scissile phosphate in the correct position for DNA hydrolysis.

PubMed: 17368670
DOI: 10.1016/J.JMB.2007.02.044

Experimental method

X-RAY DIFFRACTION (1.91 Å)