title: Similarities and singularities of three DnaK proteins from the cyanobacterium Synechocystis sp. PCC 6803.
abstract: In the genome of completely sequenced mesophilic cyanobacterium Synechocystis sp. PCC 6803 three DnaK proteins are encoded, which share a high degree of sequence identity in their N-terminal ATPase region as well as in the adjacent peptide-binding domain. However, as typical for DnaK proteins, the C-termini of the three Synechocystis proteins are highly diverse. To study the functions of the three Synechocystis DnaK proteins in more detail, we have analyzed the abundance of the individual proteins in Synechocystis cells as well as dnaK expression under various stress conditions. The presented results show that all three Synechocystis DnaK proteins interact with the same GrpE nucleotide exchange factor. A comparative analysis indicates that DnaK2 is the most abundant DnaK protein in Synechocystis cells and only the expression of dnaK2 is highly up-regulated under various stress conditions. Finally, we show that a small amino acid motif, which is typically conserved at the very C-terminus of cyanobacterial DnaK3 proteins, is essential for the DnaK3 in vivo function.
authors.affiliation: Institut für Biochemie und Molekularbiologie, ZBMZ, Albert-Ludwigs-Universität Freiburg, Stefan-Meier-Strasse 17, D-79104 Freiburg, Germany.
authors.forename: Eva
authors.initials: E
authors.lastname: Rupprecht
authors.forename: Eva
authors.initials: E
authors.lastname: Düppre
authors.forename: Dirk
authors.initials: D
authors.lastname: Schneider
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D017124:Conserved Sequence; D015964:Gene Expression Regulation, Bacterial; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D016415:Sequence Alignment; D013312:Stress, Physiological; D046939:Synechocystis / Q000235:genetics* / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C068113:GrpE protein, Bacteria; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins