Analysis of protein hydration in ultrahigh-resolution structures of the SRP GTPase Ffh

Ursula D. Ramirez, Douglas M. Freymann*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Two new structures of the SRP GTPase Ffh have been determined at 1.1 Å resolution and provide the basis for comparative examination of the extensive water structure of the apo conformation of these GTPases. A set of well defined water-binding positions have been identified in the active site of the two-domain 'NG' GTPase, as well as at two functionally important interfaces. The water hydrogen-bonding network accommodates alternate conformations of the protein side chains by undergoing local rearrangements and, in one case, illustrates binding of a solute molecule within the active site by displacement of water molecules without further disruption of the water-interaction network. A subset of the water positions are well defined in several lower resolution structures, including those of different nucleotide-binding states; these appear to function in maintaining the protein structure. Consistent arrangements of surface water between three different ultrahigh-resolution structures provide a framework for beginning to understand how local water structure contributes to protein-ligand and protein-protein binding in the SRP GTPases.

Original languageEnglish (US)
Pages (from-to)1520-1534
Number of pages15
JournalActa Crystallographica Section D: Biological Crystallography
Issue number12
StatePublished - Dec 2006


  • Ffh
  • GTPase
  • SRP
  • Ultrahigh resolution
  • Water

ASJC Scopus subject areas

  • Structural Biology

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