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Summary of our research
Phototrophic purple bacteria have revealed many intimate details of photosynthesis, and extremophilic species often yield surprising new insights. The reaction center (RC) complex of most purple bacteria with known structure contains either a cytochrome (Cyt) subunit truncated at its N-termini or alternatively, lack the subunit and instead contain the protein PufX. Here we show that the acidophilic purple bacterium Rhodopila globiformis contains a full-length Cyt subunit and also expresses a core light-harvesting (LH1) protein absent from other bacteriochlorophyll a-containing species. Our structural study lends experimental support for the longstanding hypothesis that PufX and the Cyt N-terminus are phylogenetically related and hints that the unique Rhodopila globiformis LH1 protein has evolutionary connections to a similar protein from bacteriochlorophyll b-containing species. Our structural characterization of a unusual photocomplex from an unusual phototroph has thus allowed us to address a longstanding question in bacterial photosynthesis-the origin of PufX-and has also revealed a previously unrecognized connection between BChl a- and b-containing purple bacteria. Hence our paper should appeal to a broad scientific audience, particularly those who follow photosynthesis, bioenergetics, and whose interests include the evolution and diversity of photosynthetic life.
Researcher information
Kazutoshi Tani
Appointed Professor, Mie University
Specialized area:
structural biology
Akira Mizoguchi
Professor, Mie University
Specialized area:
electron microscopy (Anatomy)
Zeng-Yu Wang-Otomo
Professor, Ibaraki Universityital
Specialized area:
Photosynthesis