Structural analysis of full-length Hfq from Escherichia coli.

The structure of full-length host factor Qβ (Hfq) from Escherichia coli obtained from a crystal belonging to space group P1, with unit-cell parameters a = 61.91, b = 62.15, c = 81.26 Å, α = 78.6, β = 86.2, γ = 59.9°, was solved by molecular replacement to a resolution of 2.85 Å and refined to R(work) and R(free) values of 20.7% and 25.0%, respectively. Hfq from E. coli has previously been crystallized and the structure has been solved for the N-terminal 72 amino acids, which cover ~65% of the full-length sequence. Here, the purification, crystallization and structural data of the full 102-amino-acid protein are presented. These data revealed that the presence of the C-terminus changes the crystal packing of E. coli Hfq. The crystal structure is discussed in the context of the recently published solution structure of Hfq from E. coli.