Glycoconjugates facilitate a myriad of biological processes, including cell-cell recognition and immune response, and they are generated by enzymes that transfer glycans. The orthologs MraY and DPAGT1 are dimeric phosphoglycosyltransferases involved in oligosaccharide biosynthesis for either bacterial peptidoglycan or eukaryotic N-linked glycans, respectively. Both enzymes play central regulatory roles, making them attractive targets for antibacterial and anticancer therapies. In our prior studies, a muraymycin A1-derived inhibitor termed APPB (aminouridyl phenoxypiperidinbenzyl butanamide) was developed. It exhibits sub-100 nM IC50 values against both MraY and DPAGT1 and has demonstrated efficacy against DPAGT1-dependent cancers, making it an excellent starting point for next-generation inhibitors. To guide their development, we determined cryo-EM structures of APPB bound to MraY or DPAGT1 at a resolution of 2.9 Å using single-particle analysis. The structures reveal that APPB, composed of a nucleoside, a central amide, and a lipid-mimetic, adopts two conformations in each protein, which correlate with the local hydrogen-bonding contacts of the central amide carbonyl. Examination of the amide carbonyl environments guides conformer selection for future DPAGT1-targeting anticancer agents. Further, comparisons of APPB-bound geometries and nucleoside interactions inform opportunities for antibacterial agents targeting MraY. Overall, our study provides design principles for MraY- or DPAGT1-specific drugs and motivates the utility of simultaneously characterizing inhibitor-bound orthologs for selective therapeutics.
", "doi": "10.1021/acschembio.5c01037", "issn": "1554-8929", "publisher": "American Chemical Society", "publication": "ACS Chemical Biology", "publication_date": "2026-05-15", "series_number": "5", "volume": "21", "issue": "5", "pages": "1018-1024" }, { "id": "authors:9taa5-b3j18", "collection": "authors", "collection_id": "9taa5-b3j18", "cite_using_url": "https://authors.library.caltech.edu/records/9taa5-b3j18", "type": "article", "title": "Application of Amber Suppression To Study the Role of Tyr M210 in Electron Transfer in Rhodobacter sphaeroides Photosynthetic Reaction Centers", "author": [ { "family_name": "Tran", "given_name": "Khoi N.", "orcid": "0000-0001-5009-8956" }, { "family_name": "Faries", "given_name": "Kaitlyn M.", "orcid": "0000-0003-1777-7716" }, { "family_name": "Magdaong", "given_name": "Nikki Cecil Macasinag", "orcid": "0000-0003-3550-8288" }, { "family_name": "Mathews", "given_name": "Irimpan I.", "orcid": "0000-0001-6254-3519" }, { "family_name": "Weaver", "given_name": "Jared B.", "orcid": "0000-0002-3823-422X" }, { "family_name": "Kirsh", "given_name": "Jacob M.", "orcid": "0000-0002-1444-2913", "clpid": "Kirsh-Jacob-M" }, { "family_name": "Holten", "given_name": "Dewey", "orcid": "0000-0003-3639-6345" }, { "family_name": "Kirmaier", "given_name": "Christine", "orcid": "0000-0003-1825-4546" }, { "family_name": "Boxer", "given_name": "Steven G.", "orcid": "0000-0001-9167-4286" } ], "abstract": "The initial light-induced electron transfer (ET) steps in the bacterial photosynthetic reaction center (RC) have been extensively studied and provide a paradigm for connecting structure and function. Although RCs have local pseudo-C2 symmetry, ET only occurs along the A branch of chromophores. Tyrosine M210 is a key symmetry-breaking residue adjacent to bacteriochlorophyll BA that bridges the primary electron donor P and the bacteriopheophytin acceptor HA. We used amber suppression to incorporate phenylalanine variants with different electron-withdrawing/-donating capabilities at the position M210. X-ray data generally reveal no appreciable structural changes due to the mutations. P* decay and P+HA- formation are multiexponential (\u223c2 to 9, \u223c10 to 60, and \u223c100 to 300 ps) and temperature dependent. The 1020 nm transient-absorption band of P+BA- is barely resolved for a few variants at 295 K and for none at 77 K. The results indicate a change from two-step ET for wild-type RCs to the dominance of one-step superexchange ET for the mutants. Resonance Stark spectroscopy reveals that the free energy of P+BA- changes by -57 to +66 meV among the phenylalanine variants. Because P+BA- apparently lies above P* in all phenylalanine variants, the perturbations primarily affect the energy denominator for superexchange mixing. The findings deepen insight into primary ET in the bacterial RC.", "doi": "10.1021/acs.jpcb.5c00082", "issn": "1520-6106", "publisher": "American Chemical Society", "publication": "Journal of Physical Chemistry B", "publication_date": "2025-04-01", "series_number": "13", "volume": "129", "issue": "13", "pages": "3317-3333" } ]