The NMR solution structure of BeF(3)(-)-activated Spo0F reveals the conformational switch in a phosphorelay system.
Two-component systems, which are comprised of a single histidine-aspartate phosphotransfer module, are the dominant signaling pathways in bacteria and have recently been identified in several eukaryotic organisms as well. A tandem connection of two or more histidine-aspartate motifs forms complex phosphorelays. While response regulators from simple two-component systems have been characterized structurally in their inactive and active forms, we address here the question of whether a response regulator from a phosphorelay has a distinct structural basis of activation. We report the NMR solution structure of BeF(3)(-)-activated Spo0F, the first structure of a response regulator from a phosphorelay in its activated state. Conformational changes were found in regions previously identified to change in simple two-component systems. In addition, a downward shift by half a helical turn in helix 1, located on the opposite side of the common activation surface, was observed as a consequence of BeF(3)(-) activation. Conformational changes in helix 1 can be rationalized by the distinct function of phosphoryl transfer to the second histidine kinase, Spo0B, because helix 1 is known to interact directly with Spo0B and the phosphatase RapB. The identification of structural rearrangements in Spo0F supports the hypothesis of a pre-existing equilibrium between the inactive and active state prior to phosphorylation that was suggested on the basis of previous NMR dynamics studies on Spo0F. A shift of a pre-existing equilibrium is likely a general feature of response regulators.
Gardino
Alexandra K
AK
Department of Biochemistry, Brandeis University, Waltham, MA 02453, USA.
Volkman
Brian F
BF
Cho
Ho S
HS
Lee
Seok-Yong
SY
Wemmer
David E
DE
Kern
Dorothee
D
D001224:Aspartic Acid / Q000378:metabolism; D001412:Bacillus subtilis / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001608:Beryllium; D005459:Fluorides; D006639:Histidine / Q000378:metabolism; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010766:Phosphorylation; D010770:Phosphotransferases / Q000737:chemistry / Q000378:metabolism; D011487:Protein Conformation; D015398:Signal Transduction
D001426:Bacterial Proteins; C080951:Spo0F protein, Bacillus subtilis; D001224:Aspartic Acid; C035982:beryllium fluoride; D006639:Histidine; D010770:Phosphotransferases; D001608:Beryllium; D005459:Fluorides