A(I) Wilson B-factor Rmerge Rmeas CC12 R-work R-free Number of atoms Macromolecules Ligands Protein residues RMS bonds ( RMS angles ( Ramachandran favoredRamachandran allowedRamachandran outliersAverage B-factor Macromolecules Ligands SolventValues in parentheses are for highest resolution shell. Rmerge P pffiffiffiffi Pn n I kl I kl n i hkl P Pn j ihklI kli iI kli iSupplementary Table 1). Moreover, a number of other striking contacts are established through salt bridges involving Asp161 on fHbp and Arg54 around the heavy chain (Fig. 4b, upper left), and Lys185 on fHbp and Asp55Asp57 on the heavy chain (Fig. 4b, decrease left), and, via hydrogen bonds involving Asn190 on fHbp and Gln101 on VH CDR3 (Fig. 4b, upper right). Further, a water-mediated hydrogen bond is formed between Thr91 within the light chain CDR3 and Tyr214 on fHbp (Fig. 4b, reduced right). Importantly, Asn215 on fHbp simultaneously contacts both the heavy and light chains of Fab 1A12, by hydrogen bonding with the gamma oxygen| DOI: 10.1038s41467-018-02827-7 | www.nature.comnaturecommunicationsARTICLELIGHT CHAINNATURE COMMUNICATIONS | DOI: ten.1038s41467-018-02827-Fab 1A12 variable regionC-term N-term HEAVY CHAINfHbpFig. two The Fab 1A12-fHbp complex crystal structure. Ribbon diagram in which the heavy and light chains of Fab 1A12 are colored green and yellow, respectively; fHbp is represented in cyan with a transparent surface. Artwork was ready using PyMOLatoms of three serine residues (heavy chain Ser106 straight, and light chain Ser30 and Ser32 indirectly via water-mediated interactions) and with Val31 (backbone nitrogen) on the light chain (Fig. 4c). A surface representation of each of the fHbp residues that interact with 1A12 reveals the nature of your 4-Vinylphenol medchemexpress conformational epitope on fHbp, lying on a surface-exposed well-ordered area of your Cterminal barrel. The epitope is concentrated within a cluster of residues targeted by the VH CDR2 and CDR3 loops, and also a extra isolated area contacted by the light chain (Fig. 5a). Basis of 1A12 cross-reactivity in spite of antigenic diversity. The elucidation with the present structure allows us to supply a detailed molecular explanation for the versatility of mAb 1A12 to recognize fHbp antigens from all 3 variant groups. Remarkably, quite a few from the fHbp residues that take part in the interaction using the Fab (12 in the 17 residues in the 1A12 epitope) are AH-7614 site conserved across the 3 various fHbp variants tested here by SPR, i.e., var1.1, var2.16, and var3.45 (Fig. 5b). Notably, residues Asp161 and Asn190 are absolutely conserved in fHbp variants 1.1, 2.16, and 3.45, and play essential roles inside the all round network of interactions with all the Fab (Fig. 4b). Further, the motif 180KIEHLK185, and residues Asn190, Val191, and Tyr214 are also conserved within the very same three variants tested by SPR. For that reason, the degree of conservation assigns a leading function to these residues inside the crossrecognition by the human mAb 1A12. The Neisseria Multi Locus Sequence Typing database now contains 1000 distinctive polypeptide sequences for fHbp obtained from naturally occurring strains31. Hence, we performed a deeper evaluation in silico and calculated the degree of conservation associated with residues in the 1A12 epitope in 984 fHbp sequence variants offered to date, which consist of sequences from serogroup B strains and from other serogroups31. Most notably, five residues (Ile181, Glu182, Leu184, Val191, and Tyr214) are one hundred conserved throughout the entire fHbp sequence repertoire (Fig.