Minimal genomes, maximal productivity: comparative genomics of the photosystem and light-harvesting complexes in the marine cyanobacterium, Prochlorococcus
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Although Prochlorococcus isolates possess the smallest genomes of any extant photosynthetic organism, this genus numerically dominates vast regions of the world’s subtropical and tropical open oceans and has evolved to become an important contributor to global biogeochemical cycles. The sequencing of 12 Prochlorococcus genomes provides a glimpse of the extensive genetic heterogeneity and, thus, physiological potential of the lineage. In this study, we present an up-to-date comparative analysis of major proteins of the photosynthetic apparatus in 12 Prochlorococcus genomes. Our analyses reveal a striking diversity within the Prochlorococcus lineage in the major protein complexes of the photosynthetic apparatus. The heterogeneity that has evolved in the photosynthetic apparatus suggests versatility in strategies for optimizing photosynthesis under conditions of environmental variability and stress. This diversity could be particularly important in ensuring the survival of a lineage whose individuals have evolved minimal genomes and, thus, relatively limited repertoires for responding to environmental challenges.
KeywordsChlorophyll b-containing cyanobacteria Environmental stress Genomic diversity Global comparative genomics Oxychlorobacteria Pcb light-harvesting antenna
This work was supported by the National Science Foundation (award no. MCB-0615680 to CST), the Woodrow Wilson National Fellowship Foundation (CST), and Williams College (CST, MER, YLW, AMF, EJ, TD). We would like to thank Christopher Warren, Office of Information Technology at Williams College for his invaluable assistance in the construction of our in-house genomic database system.
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