5U89:
reference: X-Ray Crystallography and Electron Microscopy of Cross- and Multi-Module Nonribosomal Peptide Synthetase Proteins Reveal a Flexible Architecture., Tarry MJ, Haque AS, Bui KH, Schmeing TM, Structure. 2017 May 2;25(5):783-793.e4. doi: 10.1016/j.str.2017.03.014. Epub 2017, Apr 20. PMID: 28434915

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