PMID:15846365

Citation	van Duijn, E, Bakkes, PJ, Heeren, RM, van den Heuvel, RH, van Heerikhuizen, H, van der Vies, SM and Heck, AJ (2005) Monitoring macromolecular complexes involved in the chaperonin-assisted protein folding cycle by mass spectrometry. Nat. Methods 2:371-6
Abstract	We have used native mass spectrometry to analyze macromolecular complexes involved in the chaperonin-assisted refolding of gp23, the major capsid protein of bacteriophage T4. Adapting the instrumental methods allowed us to monitor all intermediate complexes involved in the chaperonin folding cycle. We found that GroEL can bind up to two unfolded gp23 substrate molecules. Notably, when GroEL is in complex with the cochaperonin gp31, it binds exclusively one gp23. We also demonstrated that the folding and assembly of gp23 into 336-kDa hexamers by GroEL-gp31 can be monitored directly by electrospray ionization mass spectrometry (ESI-MS). These data reinforce the great potential of ESI-MS as a technique to investigate structure-function relationships of protein assemblies in general and the chaperonin-protein folding machinery in particular. A major advantage of native mass spectrometry is that, given sufficient resolution, it allows the analysis at the picomole level of sensitivity of heterogeneous protein complexes with molecular masses up to several million daltons.
Links	PubMed Online version:10.1038/nmeth753
Keywords	Bacteriophage T4/ultrastructure; Capsid Proteins/physiology; Chaperonin 10/physiology; Chaperonin 60/physiology; Chaperonins/physiology; Escherichia coli Proteins/physiology; Protein Folding; Spectrometry, Mass, Electrospray Ionization/methods
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
BPT4:VG31		GO:0051085: chaperone cofactor-dependent protein refolding	ECO:0000021:	UniProtKB:P0A6F5	P		Figure 2 shows the interaction of GroEL and Capsid assembly protein Gp31/gp31 within Enterobacteria phage T4/bacteriophage T4 only in the presence of ADP and Mg2+ using mass spectrometry	complete CACAO 13400
BPT4:CAPSH		GO:0006457:	ECO:0000314:				Figure 5 shows the folding interaction of GroEL and gp23 within Enterobacteria phage T4/bacteriophage T4 using mass spectrometry.	complete CACAO 13396

References

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