title: Conformational variability of the GTPase domain of the signal recognition particle receptor FtsY.
abstract: The prokaryotic signal recognition particle Ffh and its receptor FtsY allow targeting of proteins into or across the plasma membrane. The targeting process is GTP dependent and the two proteins constitute a distinct GTPase family. The receptor FtsY is composed of A and NG domains where the NG's GTPase domain plays a critical role in the targeting process. In this study, we describe two X-ray structures determined independently of each other of the NG domain of FtsY from Mycoplasma mycoides (MmFtsY). The two structures are markedly different in three of the nucleotide-binding segments, GI (P-loop), GII, and GIII, making only one of the structures compatible with nucleotide binding. Interestingly, the two distinct conformations of the nucleotide-binding segments of MmFtsY are similar to the apo- and ADP-loaded forms of certain ATPases. The structure of the extended interface between the A and NG domains of MmFtsY provides new insights into the role of the A domain for phospholipid interaction.
authors.affiliation: Umeå Centre for Molecular Pathogenesis, Umeå University, Sweden.
authors.forename: Talal
authors.initials: T
authors.lastname: Gariani
authors.forename: Tore
authors.initials: T
authors.lastname: Samuelsson
authors.forename: A Elisabeth
authors.initials: AE
authors.lastname: Sauer-Eriksson
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D018360:Crystallography, X-Ray; D020558:GTP Phosphohydrolases / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009176:Mycoplasma mycoides / Q000201:enzymology / Q000235:genetics; D017434:Protein Structure, Tertiary; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry*; D016415:Sequence Alignment; D018271:Signal Recognition Particle / Q000378:metabolism; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; C087406:FtsY protein, Bacteria; D018160:Receptors, Cytoplasmic and Nuclear; D018271:Signal Recognition Particle; D000251:Adenosine Triphosphatases; D020558:GTP Phosphohydrolases