Coexistence of group I and group II chaperonins in the archaeon Methanosarcina mazei.
Two distantly related classes of cylindrical chaperonin complexes assist in the folding of newly synthesized and stress-denatured proteins in an ATP-dependent manner. Group I chaperonins are thought to be restricted to the cytosol of bacteria and to mitochondria and chloroplasts, whereas the group II chaperonins are found in the archaeal and eukaryotic cytosol. Here we show that members of the archaeal genus Methanosarcina co-express both the complete group I (GroEL/GroES) and group II (thermosome/prefoldin) chaperonin systems in their cytosol. These mesophilic archaea have acquired between 20 and 35% of their genes by lateral gene transfer from bacteria. In Methanosarcina mazei Gö1, both chaperonins are similarly abundant and are moderately induced under heat stress. The M. mazei GroEL/GroES proteins have the structural features of their bacterial counterparts. The thermosome contains three paralogous subunits, alpha, beta, and gamma, which assemble preferentially at a molar ratio of 2:1:1. As shown in vitro, the assembly reaction is dependent on ATP/Mg2+ or ADP/Mg2+ and the regulatory role of the beta subunit. The co-existence of both chaperonin systems in the same cellular compartment suggests the Methanosarcina species as useful model systems in studying the differential substrate specificity of the group I and II chaperonins and in elucidating how newly synthesized proteins are sorted from the ribosome to the proper chaperonin for folding.
Klunker
Daniel
D
Department of Cellular Biochemistry, Max Planck Institute of Biochemistry, Am Klopferspitz 18a, 82152 Martinsried, Germany.
Haas
Bernd
B
Hirtreiter
Angela
A
Figueiredo
Luis
L
Naylor
Dean J
DJ
Pfeifer
Günter
G
Müller
Volker
V
Deppenmeier
Uwe
U
Gottschalk
Gerhard
G
Hartl
F Ulrich
FU
Hayer-Hartl
Manajit
M
D000251:Adenosine Triphosphatases / Q000737:chemistry; D000255:Adenosine Triphosphate / Q000378:metabolism; D000595:Amino Acid Sequence; D001105:Archaea; D018835:Chaperonin 10 / Q000378:metabolism; D018834:Chaperonin 60 / Q000378:metabolism; D003001:Cloning, Molecular; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D015151:Immunoblotting; D008027:Light; D008274:Magnesium / Q000378:metabolism; D017020:Methanosarcina / Q000378:metabolism*; D008854:Microscopy, Electron; D008957:Models, Genetic; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D011401:Promoter Regions, Genetic; D017510:Protein Folding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012542:Scattering, Radiation; D017386:Sequence Homology, Amino Acid; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D013884:Thiosulfate Sulfurtransferase / Q000737:chemistry; D013997:Time Factors
D018835:Chaperonin 10; D018834:Chaperonin 60; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D013884:Thiosulfate Sulfurtransferase; D000251:Adenosine Triphosphatases; D008274:Magnesium