A 71-kDa protein from Halobacterium salinarium belongs to a ubiquitous P-loop ATPase superfamily with head-rod-tail stru
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© Springer-Verlag 1998
O R I G I N A L PA P E R
Andreas Ruepp · Gerhard Wanner · Jörg Soppa
A 71-kDa protein from Halobacterium salinarium belongs to a ubiquitous P-loop ATPase superfamily with head-rod-tail structure
Received: 25 March 1997 / Accepted: 11 August 1997
Abstract The nucleotide sequence of a genomic fragment from Halobacterium salinarium containing an open reading frame encoding a protein with a calculated molecular mass of 71 kDa was determined. Database searches revealed that this protein, Hp71, has similarities to eukaryotic cytoskeletal proteins. Heterologous production of Hp71 in Escherichia coli allowed the isolation of antiHp71 antibodies. The antibodies were used (1) to verify the production of Hp71 in H. salinarium and (2) to determine its cytoplasmic localization by immune electron microscopy. Homologous overproduction of Hp71 in H. salinarium and heterologous production in Haloferax volcanii resulted in modifications of cell morphology from rods to extended rods, and from pleiomorphic cells to rods, respectively. Structure prediction methods indicated that Hp71 has a head-rod-tail configuration, including an N-terminal domain with a nucleotide binding motif (Ploop), and an extended discontinuous coiled-coil domain of 330 amino acids. To identify related proteins, the complete genomes of Haemophilus influenzae, Mycoplasma genitalium, and Methanococcus jannaschii were searched for deduced proteins with extended coiled-coil domains. Only one or two proteins were found for each organism, showing that Hp71 is one of only a few prokaryotic intracellular proteins with extended coiled-coil domains. The phenotype upon overproduction and the similarity of Hp71 to the SMC superfamily of P-loop head-rod-tail proteins
A. Ruepp · J. Soppa1 (Y) MPI für Biochemie, Am Klopferspitz 18a, D-82152 Martinsried, Germany G. Wanner Universität München, Botanisches Institut, Menzinger Strasse 67, D-80638 München, Germany Present address: W. Goethe-Universität, Biozentrum Niederursel, Institut für Mikrobiologie, Marie-Curie-Strasse 9, D-60439 Frankfurt, Germany Tel. +49-69-798-29564; Fax +49-69-798-29564 e-mail: [email protected]
1 J.
(named after SMC1, which is involved in the “stability of minichromosomes” in yeast) indicate that Hp71 might be involved in cytoskeleton formation and/or chromosome partitioning in H. salinarium. Key words Archaea · Halobacterium salinarium · Coiled coil · Cytoskeleton · Chromosome partitioning · Cell morphology · MukB · P115 · SMC1
Introduction Many different proteins contain sequences that are able to participate in coiled coils, i.e., bundles of two or more helices wound into a superhelix. The coiled-coil structure allows a specific and stable interaction between proteins that is exploited by proteins as different as transcription factors and cytoskeletal filament proteins. Structure determination of a variety of complexes with coiled-coil domains has revealed their great structural variability and has facilitated the prediction of coiled coils from primary sequences
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