A quantitative assessment of (bacterio)chlorophyll assignments in the cryo-EM structure of the Chloracidobacterium thermophilum reaction center.

Autor: Gisriel CJ; Department of Chemistry, Yale University, New Haven, CT, 06520, USA., Flesher DA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA., Long Z; Department of Chemistry, Yale University, New Haven, CT, 06520, USA., Liu J; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA., Wang J; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA., Bryant DA; Department of Biochemistry and Molecular Biology, The Pennsylvania State University, University Park, PA, 16802, USA., Batista VS; Department of Chemistry, Yale University, New Haven, CT, 06520, USA., Brudvig GW; Department of Chemistry, Yale University, New Haven, CT, 06520, USA. gary.brudvig@yale.edu.; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA. gary.brudvig@yale.edu.
Jazyk: angličtina
Zdroj: Photosynthesis research [Photosynth Res] 2024 Dec; Vol. 162 (2-3), pp. 187-196. Date of Electronic Publication: 2023 Sep 25.
DOI: 10.1007/s11120-023-01047-5
Abstrakt: Chlorophylls and bacteriochlorophylls are the primary pigments used by photosynthetic organisms for light harvesting, energy transfer, and electron transfer. Many molecular structures of (bacterio)chlorophyll-containing protein complexes are available, some of which contain mixtures of different (bacterio)chlorophyll types. Differentiating these, which sometimes are structurally similar, is challenging but is required for leveraging structural data to gain functional insight. The reaction center complex from Chloroacidobacterium thermophilum has a hybrid (bacterio)chlorophyll antenna system containing both chlorophyll a and bacteriochlorophyll a molecules. The recent availability of its cryogenic electron microscopy (cryo-EM) structure provides an opportunity for a quantitative analysis of their identities and chemical environments. Here, we describe a theoretical basis for differentiating chlorophyll a and bacteriochlorophyll a in a cryo-EM map, and apply the approach to the experimental cryo-EM maps of the (bacterio)chlorophyll sites of the chloroacidobacterial reaction center. The comparison reveals that at ~ 2.2-Å resolution, chlorophyll a and bacteriochlorophyll a are easily distinguishable, but the orientation of the bacteriochlorophyll a acetyl moiety is not; however, the latter can confidently be assigned by identifying a hydrogen bond donor from the protein environment. This study reveals the opportunities and challenges in assigning (bacterio)chlorophyll types in structural biology, the accuracy of which is vital for downstream investigations.
Competing Interests: Declarations. Conflict of interest: The authors declare that they have no conflict of interest.
(© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)
Databáze: MEDLINE
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