Structures of chaperonins from an intracellular symbiont and their functional expression in Escherichia coli groE mutants.
An intracellular symbiont harbored by the aphid bacteriocyte, a specialized fat body cell, synthesizes in vivo substantially only one protein, symbionin, which is a member of the chaperonin-60 family of molecular chaperones. Nucleotide sequence determination of the symbionin region of the endosymbiont genome revealed that it contains the two-cistron operon sym. Just like the Escherichia coli groE operon, the sym operon was dually led by a heat shock and an ordinary promoter sequence. According to the nucleotide sequence, symbionin was 85.5% identical to GroEL of E. coli at the amino acid sequence level. SymS, another protein encoded in the sym operon, which is a member of chaperonin-10, was 79.6% identical to GroES. Complementation experiments with E. coli groE mutants showed that the chaperonin-10 and chaperonin-60 genes from the endosymbiont are expressed in E. coli and that they can function as molecular chaperones together with endogenous GroEL and GroES, respectively.
Zoological Institute, Faculty of Science, University of Tokyo, Japan.
C
C
Ohtaka
H
H
Nakamura
H
H
Ishikawa
D000595:Amino Acid Sequence; D000818:Animals; D001042:Aphids / Q000382:microbiology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D001483:Base Sequence; D018835:Chaperonin 10; D018834:Chaperonin 60; D018833:Chaperonins; D003001:Cloning, Molecular; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005816:Genetic Complementation Test; D006360:Heat-Shock Proteins / Q000235:genetics; D006860:Hydrogen Bonding; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009876:Operon; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000737:chemistry / Q000235:genetics*; D015183:Restriction Mapping; D016415:Sequence Alignment; D013559:Symbiosis
D001426:Bacterial Proteins; D018835:Chaperonin 10; D018834:Chaperonin 60; D006360:Heat-Shock Proteins; D011506:Proteins; C044322:SymL protein, Bacteria; D018833:Chaperonins