1R4V:
reference: The crystal structure of Aq_328 from the hyperthermophilic bacteria Aquifex aeolicus shows an ancestral histone fold., Qiu Y, Tereshko V, Kim Y, Zhang R, Collart F, Yousef M, Kossiakoff A, Joachimiak A, Proteins. 2006 Jan 1;62(1):8-16. PMID: 16287087

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