Meng Li is a senior graduate student in the laboratory of Barry Bruce in the Department of Biochemistry & Cellular and Molecular Biology. His research involves the investigation of the structural organization and evolutionary origins of the photosynthetic photosystem I complex (PSI). PSI is one of the largest membrane proteins in nature and a key component for oxygenic photosynthesis. Specifically, Meng has been investigating the structural complexes of this critical photosynthetic center in higher plants and ancestral cyanobacterial bluegreen algal species which are evolutionary progenitors of higher plant chloroplasts.
His recent work is on the photosystem I complex (PSI) from an unusual species of cyanobacteria, Chroococcidiopsis sp. TS-821 (TS-821) found in hot springs from northern Thailand. Meng’s structural work shows that unlike higher plant PSI which are monomeric, and ancestral cyanobacteria which are trimeric, the Chroococcidiopsis PSI complex forms an unusual tetrameric complex. From analysis of the structure and phylogeny of the key protein (PsaL) which affects PSI oligomerization, Meng and co-workers have generated a novel PSI evolutionary model: the tetrameric PSI may be an evolutionary intermediate between the ancestral trimeric and the modern monomeric plant PSI. This also provides additional insight regarding the cyanobacterial origin of plastid evolution as well. This work was recently accepted for publication in the prestigious journal The Plant Cell.