4CHG:
reference: Crystal structure of the VapBC-15 complex from Mycobacterium tuberculosis reveals a two-metal ion dependent PIN-domain ribonuclease and a variable mode of toxin-antitoxin assembly., Das U, Pogenberg V, Subhramanyam UK, Wilmanns M, Gourinath S, Srinivasan A, J Struct Biol. 2014 Oct 22;188(3):249-258. doi: 10.1016/j.jsb.2014.10.002. PMID: 25450593

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