A Highly Evolutionarily Conserved Mitochondrial Protein Is Structurally Related to the Protein Encoded by the <i>Escherichia coli groEL</i> Gene

McMullin, T W; Hallberg, Richard L.

doi:10.1128/mcb.8.1.371-380.1988

Cited by 99 publications

(9 citation statements)

References 56 publications

(60 reference statements)

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“…Recently groEL has been shown to be related to an animal mitochondria! protein that is increased on heat shock (McMullin and Hallberg, 1988) and to a chloroplast protein that is involved in assembling the oligomeric enzyme Rubisco (Hemmingsen etaL 1988).…”

Section: Introductionmentioning

confidence: 99%

Hsr-omega, A Novel Gene Encoded by a Drosophila Heat Shock Puff

Pardue¹,

Bendena²,

Fini³

et al. 1990

The Biological Bulletin

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Although originally identified because of its abundant transcription in heat shock, the hsr-omega gene is active, at generally lower levels, in non-stressed cells. The locus produces an unusual set of three transcripts. Evidence from a variety of experiments suggests that one of these transcripts acts in the nucleus, possibly to regulate the activity of a nuclear protein. Another of the transcripts appears to act in the cytoplasm, possibly monitoring or regulating some aspect of translation. The two transcripts together could have a role in coordinating nuclear and cytoplasmic activity. A number of processes occur in eukaryotic cells in which nuclear and cytoplasmic activities need to be coordinated; we suggest that hsr-omega plays a role in such coordination.

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Section: Introductionmentioning

confidence: 99%

Hsr-omega, A Novel Gene Encoded by a Drosophila Heat Shock Puff

Pardue¹,

Bendena²,

Fini³

et al. 1990

The Biological Bulletin

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“…Hsp60s and Hsp10s share 7-fold symmetry as befits their subunit-to-subunit interaction in cycles of ATP-dependent binding and dissociation. Electron microscopy of Hsp60s from E. coli (Hendrix, 1979;Hohn et al, 1979), yeast mitochondria (McMullin & Hallberg, 1988), and higher plant † Supported by the National Science Foundation (MCB-9512711), the Louisiana Education Quality Support Fund -RD-A-29, and the Tulane/Xavier Center for Bioenvironmental Research.…”

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confidence: 99%

Temperature Dependence of Backbone Dynamics in Loops of Human Mitochondrial Heat Shock Protein 10

Landry

Maskos

1997

Biochemistry

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A highly flexible, yet conserved polypeptide loop of Hsp10 mediates binding to Hsp60 in the course of chaperonin-dependent protein folding. Previous transferred nuclear Overhauser effect (trNOE) studies with peptides based on the mobile loop of the Escherichiacoli and bacteriophage T4 Hsp10s suggested that the mobile loop adopts a characteristic hairpin turn upon binding to the E. coli Hsp60 GroEL. In this paper, we identify the sequence and characterize the nascent structure and dynamics of the 18-residue mobile loop in the 15N-enriched human Hsp10. We also identify four residues of another flexible loop, the roof beta hairpin. The mobile loop and/or roof beta hairpin of several subunits are absent from the X-ray crystal structure of human Hsp10. NMR data suggest that the mobile loop of Hsp10 preferentially samples a hairpin conformation despite the fact that the backbone motion resembles that of a disordered polypeptide. Analysis of backbone dynamics by measurement of 15N relaxation times, T1 and T2, and the 1H-15N nuclear Overhauser effect (1H-15N NOE) indicates that motion is greatest near the center of the loop. Inversion of the temperature dependence of the T1 near the center of the loop marks a transition to motion with a dominant time scale of less than 3 ns. Analysis of the relaxation data by spectral density mapping shows that subnanosecond motion increases uniformly along the loop at elevated temperatures, whereas nanosecond motion increases near the ends of the loop and decreases near the center of the mobile loop. The transition to dominance by fast motion in the center of the loop occurs at a distance from the well-structured part of Hsp10 that is equal to the persistence length of an unstructured polypeptide. Simulation of the spectral density function for the 15N resonance and its temperature dependence using the Lipari-Szabo formalism suggests that the dominant time scales of loop motion range from 0.6 to 18 ns. For comparison, the time scale for molecular rotation of the 70 kDa Hsp10 heptamer is estimated to be 37 ns. Complex behavior of the T2 relaxation time indicates that motion also occurs on longer time scales. All of the modes of loop motion are likely to have an impact on Hsp10/Hsp60 interaction and therefore affect Hsp10/Hsp60 function as a chaperonin.

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“…They are of biological importance in preventing incorrect interactions between polypeptide chains during de noVo protein synthesis and protecting pre-existing proteins from denaturation under cellular stress. The chaperonins of the cpn60 class are highly conserved throughout evolution (McMullin & Hallberg, 1988;Horovitz et al, 1993), with the corresponding prokaryotic cpn60 being GroEL. The GroEL complex has been shown by electron microscopy and X-ray crystallography to be a tetradecamer of identical subunits, each with a M r of 57 300 (Braig et al, 1994(Braig et al, , 1995Hendrix, 1979;Ishii et al, 1992).…”

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confidence: 99%

Determination of Regions in the Dihydrofolate Reductase Structure That Interact with the Molecular Chaperonin GroEL

Hugo

Frieden

1996

Biochemistry

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Dihydrofolate reductase (DHFR) from Escherichia coli does not interact with the molecular chaperonin GroEL regardless of whether the interaction is initiated from the native or the unfolded state. In contrast, murine DHFR shows a strong interaction with GroEL. Using the structure of human DHFR as a model for the murine protein, a superimposition of the two structures shows that there are three distinct external loops in the eukaryotic DHFR that are not present in the E. coli protein. Removal of one loop (residues 99-108) from the eukaryotic murine DHFR has no effect on the interaction with GroEL. On the basis of the differences in structures, we inserted either of two surface loops of murine DHFR into the corresponding regions of E. coli DHFR. In the first mutant (EcDHFR-i(9)36), residues 36 and 37 (L-N) of E. coli DHFR were replaced with the nine amino acid sequence T-T-S-S-V-E-G-K-Q. In the second mutant (EcDHFR-i(7)136), residues 136-139 (V-F-S-E) of E. coli DHFR were replaced with the seven amino acid sequence L-P-E-Y-P-G-V. Both E. coli DHFR mutants formed a complex with GroEL starting from either the native or the unfolded states of DHFR. The binding was specific since the presence of MgATP caused the release of the proteins from GroEL. As with murine DHFR, nonnative conformations of EcDHFR-i(9)36 and EcDHFR-i(7)136 are bound to GroEL. Fluorescence titration techniques were used to quantitate the interaction between GroEL and these proteins. A simple chromatographic procedure was developed to remove contaminating tryptophan containing peptides from GroEL samples. The mutant EcDHFR-i(7)136 binds to GroEL with a stoichiometry of 4-5 mol of DHFR per mol of GroEL tetradecamer, while murine DHFR binds to GroEL with a stoichiometry of 2 mol of DHFR per mol of GroEL tetradecamer. Both murine DHFR and EcDHFR-i(7)136 bind to GroEL very tightly, with equilibrium dissociation constants of less than 85 nM.

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A Highly Evolutionarily Conserved Mitochondrial Protein Is Structurally Related to the Protein Encoded by the Escherichia coli groEL Gene

Cited by 99 publications

References 56 publications

Hsr-omega, A Novel Gene Encoded by a Drosophila Heat Shock Puff

Hsr-omega, A Novel Gene Encoded by a Drosophila Heat Shock Puff

Temperature Dependence of Backbone Dynamics in Loops of Human Mitochondrial Heat Shock Protein 10

Determination of Regions in the Dihydrofolate Reductase Structure That Interact with the Molecular Chaperonin GroEL

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