The UCLA biochemists also report 199 related proteins that presumably do similar things in 50 other bacteria, Yeates said.
"Our findings blur the distinction between eukaryotic cells and those of prokaryotes by arguing that bacterial cells are more complex than one would imagine, and that many of them have evolved sophisticated mechanisms," Yeates said.
While microcompartments have been directly observed in only a few organisms, "surely there will be many more," Yeates said. "The capacity to create subcellular compartments is very widespread across diverse microbes. We believe that many prokaryotes have the capacity to create subcellular compartments to organize their metabolic activities."
Yeates' research team includes research scientist and lead author Cheryl Kerfeld; Michael Sawaya, a research scientist with UCLA and the Howard Hughes Medical Institute; Shiho Tanaka, a former UCLA undergraduate who is starting graduate work at UCLA this fall in biochemistry; and UCLA chemistry and biochemistry graduate student Morgan Beeby.
The structure of the carboxysome shows a repeating pattern of six protein molecules packed closely together.
"We didn't know six would be the magic number," Yeates said. "What surprises me is how nearly these six protein molecules fill the space between them. If you take six pennies and place them in the shape of a ring, that leaves a large space in the middle. Yet the shape of this protein
Source:University of California - Los Angeles