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Rhodobacter capsulatus Forms a Compact Crescent-Shaped LH1-RC Photocomplex

21 Feb 2023

Summary of our research

All life on Earth depends on photosynthesis, and despite over 100 years of research on this important process, much remains unknown about its basic mechanism. This includes, in particular, structure-function relationships of the photosynthetic machinery. Due to their close phylogenetic relationship and similar spectroscopic behavior,Rhodobacter capsulatus photocomplexes have long been used as alternatives to those of Rhodobacter sphaeroides (the most widely used model organism in bacterial photosynthesis) under the assumption that their corresponding complexes are structurally similar. Although this is true for the structurally more conserved reaction centers (RC), our work has demonstrated that structural differences in the RC-surrounding light-harvesting complex (LH1) between these two closely related species are significant and that a broad diversity is obviously possible in the makeup of this important component of the photosynthetic apparatus. In this regard, our study provides an excellent example of the danger in making broad-sweeping generalizations about even closely related species without first doing the experiment.

The native Rhodobacter capsulatus LH1-RC structure reveals the precise location and interactions of both the pigments and proteins that form the smallest of all known LH1-RC complexes and addresses both structural and molecular aspects of the complex at atomic resolution. Our study therefore provides for the first time both a snapshot of the inner workings of a minimal photosynthetic energy-conversion machine and a "parts list" of the components required to for a functional photocomplex. Thus, our paper published on Nature communications would appeal to a broad scientific audience, particularly those whose interests include photosynthesis and bioenergetics, structural biology, and the diversity of photosynthetic life on Earth.


Researcher information

Kazutoshi Tani

Appointed Professor, Mie University

Specialized area:

structural biology

Akira Mizoguchi

Professor, Mie University

Specialized area:

electron microscopy (Anatomy)

Bruno Humbel

Electron Microscopy Expert, Okinawa Institute of Science and Technology Graduate University

Specialized area:

electron microscopy

Zeng-Yu Wang-Oomo

Professor, Ibaraki University

Specialized area: