3WOE:
reference: Structural basis for promoter specificity switching of RNA polymerase by a phage factor., Tagami S, Sekine S, Minakhin L, Esyunina D, Akasaka R, Shirouzu M, Kulbachinskiy A, Severinov K, Yokoyama S, Genes Dev. 2014 Mar 1;28(5):521-31. doi: 10.1101/gad.233916.113. PMID: 24589779

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