Crystal structure of ribosomal protein L1 from the bacterium Aquifex aeolicus

The crystal structure of ribosomal protein L1 from the bacterium Aquifex aeolicus was solved by the molecular-replacement method and refined to R _cryst = 19.4% and R _free = 25.1% at 2.1 Å protein consists of two domains linked together by a flexible hinge region. In the structure under consideration, the domains are in close proximity and adopt a closed conformation. Earlier, this conformation has been found in the structure of protein L1 from the bacterium Thermus thermophilus, whereas the structures of archaeal L1 proteins and the structures of all L1 proteins in the RNA-bound form have an open conformation. The fact that a closed conformation was found in the structures of two L1 proteins which crystallize in different space groups and belong to different bacteria suggests that this conformation is a characteristic feature of L1 bacterial proteins in the free form.