2C6W:
reference: Crystal structure of penicillin-binding protein 1a (PBP1a) reveals a mutational hotspot implicated in beta-lactam resistance in Streptococcus pneumoniae., Contreras-Martel C, Job V, Di Guilmi AM, Vernet T, Dideberg O, Dessen A, J Mol Biol. 2006 Jan 27;355(4):684-96. Epub 2005 Nov 9. PMID: 16316661

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