Manakova E, Mikutenaite M, Golovenko D, Gražulis S, Tamulaitiene G. Crystal structure of restriction endonuclease Kpn2I of CCGG-family.
Biochim Biophys Acta Gen Subj 2021;
1865:129926. [PMID:
33965438 DOI:
10.1016/j.bbagen.2021.129926]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2020] [Revised: 05/02/2021] [Accepted: 05/04/2021] [Indexed: 10/21/2022]
Abstract
BACKGROUND
Restriction endonucleases belong to prokaryotic restriction-modification systems, that protect host cells from invading DNA. Type II restriction endonucleases recognize short 4-8 bp sequences in the target DNA and cut both DNA strands producing double strand breaks. Type II restriction endonuclease Kpn2I cleaves 5'-T/CCGGA DNA sequence ("/" marks the cleavage position). Analysis of protein sequences suggested that Kpn2I belongs to the CCGG-family, which contains ten enzymes that recognize diverse nucleotides outside the conserved 5'-CCGG core and share similar motifs for the 5'-CCGG recognition and cleavage.
METHODS
We solved a crystal structure of Kpn2I in a DNA-free form at 2.88 Å resolution. From the crystal structure we predicted active center and DNA recognition residues and tested them by mutational analysis. We estimated oligomeric state of Kpn2I by SEC-MALS and performed plasmid DNA cleavage assay to elucidate DNA cleavage mechanism.
RESULTS
Structure comparison confirmed that Kpn2I shares a conserved active site and structural determinants for the 5'-CCGG tetranucleotide recognition with other restriction endonucleases of the CCGG-family. Guided by structural similarity between Kpn2I and the CCGG-family restriction endonucleases PfoI and AgeI, Kpn2I residues involved in the outer base pair recognition were proposed.
CONCLUSIONS
Kpn2I is an orthodox Type IIP restriction endonuclease, which acts as a dimer. Kpn2I shares structural similarity to the CCGG-family restriction endonucleases PfoI, AgeI and PspGI.
GENERAL SIGNIFICANCE
The Kpn2I structure concluded the studies of the CCGG-family, covering detailed structural and biochemical characterization of eleven restriction enzymes and their complexes with DNA.
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