Global aggregation of newly translated proteins in an Escherichia coli strain deficient of the chaperonin GroEL.
In a newly isolated temperature-sensitive lethal Escherichia coli mutant affecting the chaperonin GroEL, we observed wholesale aggregation of newly translated proteins. After temperature shift, transcription, translation, and growth slowed over two to three generations, accompanied by filamentation and accretion (in approximately 2% of cells) of paracrystalline arrays containing mutant chaperonin complex. A biochemically isolated inclusion body fraction contained the collective of abundant proteins of the bacterial cytoplasm as determined by SDS/PAGE and proteolysis/MS analyses. Pulse-chase experiments revealed that newly made proteins, but not preexistent ones, were recruited to this insoluble fraction. Although aggregation of "stringent" GroEL/GroES-dependent substrates may secondarily produce an "avalanche" of aggregation, the observations raise the possibility, supported by in vitro refolding experiments, that the widespread aggregation reflects that GroEL function supports the proper folding of a majority of newly translated polypeptides, not just the limited number indicated by interaction studies and in vitro experiments.
Chapman
Eli
E
The Scripps Research Institute, La Jolla, CA 92037, USA.
Farr
George W
GW
Usaite
Renata
R
Furtak
Krystyna
K
Fenton
Wayne A
WA
Chaudhuri
Tapan K
TK
Hondorp
Elise R
ER
Matthews
Rowena G
RG
Wolf
Sharon G
SG
Yates
John R
JR
Pypaert
Marc
M
Horwich
Arthur L
AL
D018834:Chaperonin 60 / Q000235:genetics / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000378:metabolism; D002479:Inclusion Bodies / Q000378:metabolism; D008780:Methyltransferases / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D010641:Phenotype; D014176:Protein Biosynthesis / Q000235:genetics*; D040901:Proteomics; D012995:Solubility; D013379:Substrate Specificity; D013696:Temperature; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics
D018834:Chaperonin 60; D029968:Escherichia coli Proteins; D008780:Methyltransferases; C058170:metE protein, E coli