A structural model for the GroEL chaperonin

Marco, Sergio; Valpuesta, JoséMaría; Rivas, Germán; Andrés, Germán; Martín, Carmen San; Carrascosa, J.L.

doi:10.1111/j.1574-6968.1993.tb05980.x

Cited by 6 publications

(4 citation statements)

References 25 publications

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“…The presumptive relationship between Asp60 and Hsp62 will require further definition. Modified forms of GroEL appear in Escherichia coli during the heat shock response and, following prolonged storage, exhibit retarded migration in SDS-PAGE and an increasingly acidic isoelectric point on twodimensional gels (29,41). Preliminary Southern blot analysis (data not shown) has ruled out the possibility that Asp60 represents the product of a related gene, as observed for Mycobacterium spp., streptomycetes, and Synechocystis spp.…”

Section: Discussionmentioning

confidence: 99%

“…Multiple forms with various isoelectric points are also apparent in the IEF dimension and are similar to the forms observed with Hsp62, albeit slightly more basic. Additional experiments are necessary to confirm the identity of this gene product and to determine whether Asp60 represents an unrelated protein, the product of a related gene (18,24,26,38), or a modified version (posttranslational modification) of Hsp62 (11,29,41). (10).…”

Section: Sds-page Analysis Of B Abortus Protein Synthesis In Responsmentioning

confidence: 99%

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Protein synthesis in Brucella abortus induced during macrophage infection

1995

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Brucella abortus is a facultative, intracellular, pathogenic bacterium that replicates within macrophages and resists macrophage microbicidal mechanisms. To study gene expression and to elucidate the defense mechanisms used by B. abortus to resist destruction within macrophages, protein synthesis by B. abortus was examined by pulse-labeling techniques during intracellular growth within J774A.1, a macrophage-like cell line. Prominent changes observed include increased synthesis of Brucella proteins with estimated molecular masses of 62, 28, 24, and 17 kDa. The 62-kDa protein was identified by immunoprecipitation analysis as Hsp62, a GroEL homolog. A protein of 60 kDa was expressed during acid shock and may represent a modified form of Hsp62. The 28-and 17-kDa proteins have not been observed under any in vitro stress condition and presumably represent macrophage-specific induction. The 24-kDa protein comigrates with an unidentified protein induced by acid shock, designated Asp24. Expression of Asp24 is optimal at pH values below 4.0 and within the first 3 h following a shift from pH 7.3 to 3.8. This corresponds directly with a period of optimal bacterial survival at a reduced pH and suggests an active role for this protein in resistance to such environments. The identification of these gene products and the mechanisms controlling their expression is an important step in understanding the resistance of Brucella spp. to intracellular destruction within macrophages.

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Section: Discussionmentioning

confidence: 99%

Section: Sds-page Analysis Of B Abortus Protein Synthesis In Responsmentioning

confidence: 99%

Protein synthesis in Brucella abortus induced during macrophage infection

1995

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“…Micrographs were digitized using a Eikonix IEEE-488 camera with a sampling window corresponding to 4.7 A/pixel. Image processing of individual particles was carried out as described by Carrascosa et al (1990), except that average images were calculated using an improved alignment algorithm (Penczek et al, 1992;Marco et al, 1993). In the case of actin binary complex preparations, particles having a central stain-filled domain were separated from those showing a stain-penetrating central region using a Kohonen-based self-organizing map classifier (Kohonen, 1990;Marabini and Carazo, 1994).…”

Section: Electron Microscopy and Image Processingmentioning

confidence: 99%

Reversible interaction of beta-actin along the channel of the TCP-1 cytoplasmic chaperonin

Marco

Carrascosa

Valpuesta

1994

Biophysical Journal

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The cytoplasm of eukaryotes contains a heteromeric toroidal chaperonin assembled from the t-complex TCP-1 and several other related polypeptides. The structure of the TCP-1 cytoplasmic chaperonin and that of the binary complex formed between this chaperonin and unfolded beta-actin have been studied using electron microscopy and image processing techniques. Two-dimensional averaging of front views reveals a circular stain-excluding mass surrounding a central stain-penetrating region in which the stain is excluded upon actin binding. Sections of a three-dimensional reconstruction of the chaperonin show that the inner core is an empty channel that becomes filled upon binary complex formation with unfolded beta-actin. Upon incubation with Mg-ATP, the beta-actin:chaperonin complex discharges the actin such that the chaperonin central cavity reappears. Side views from different forms of TCP-1 reveals that upon Mg-ATP binding, the cytoplasmic chaperonin undergoes a structural rearrangement that is confirmed using a new classification method.

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“…Neurodegenerative disorders may be a consequence of proteostasis deficiency, while cancer could result from enhanced proteostasis capacity ( Powers et al, 2009 ). Key structural studies of molecular chaperones in the 1990s ( Marco et al, 1993 ) revealed these as essential components of the network governing protein homeostasis. Though in vitro studies revealed much on the basic principles of protein folding, how proteins fold in the crowded in vivo cellular environment remains to be fully understood.…”

Section: Introductionmentioning

confidence: 99%

The TRiCky Business of Protein Folding in Health and Disease

Ghozlan

Cox

Nierenberg

et al. 2022

Front. Cell Dev. Biol.

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Maintenance of the cellular proteome or proteostasis is an essential process that when deregulated leads to diseases like neurological disorders and cancer. Central to proteostasis are the molecular chaperones that fold proteins into functional 3-dimensional (3D) shapes and prevent protein aggregation. Chaperonins, a family of chaperones found in all lineages of organisms, are efficient machines that fold proteins within central cavities. The eukaryotic Chaperonin Containing TCP1 (CCT), also known as Tailless complex polypeptide 1 (TCP-1) Ring Complex (TRiC), is a multi-subunit molecular complex that folds the obligate substrates, actin, and tubulin. But more than folding cytoskeletal proteins, CCT differs from most chaperones in its ability to fold proteins larger than its central folding chamber and in a sequential manner that enables it to tackle proteins with complex topologies or very large proteins and complexes. Unique features of CCT include an asymmetry of charges and ATP affinities across the eight subunits that form the hetero-oligomeric complex. Variable substrate binding capacities endow CCT with a plasticity that developed as the chaperonin evolved with eukaryotes and acquired functional capacity in the densely packed intracellular environment. Given the decades of discovery on the structure and function of CCT, much remains unknown such as the scope of its interactome. New findings on the role of CCT in disease, and potential for diagnostic and therapeutic uses, heighten the need to better understand the function of this essential molecular chaperone. Clues as to how CCT causes cancer or neurological disorders lie in the early studies of the chaperonin that form a foundational knowledgebase. In this review, we span the decades of CCT discoveries to provide critical context to the continued research on the diverse capacities in health and disease of this essential protein-folding complex.

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A structural model for the GroEL chaperonin

Cited by 6 publications

References 25 publications

Protein synthesis in Brucella abortus induced during macrophage infection

Protein synthesis in Brucella abortus induced during macrophage infection

Reversible interaction of beta-actin along the channel of the TCP-1 cytoplasmic chaperonin

The TRiCky Business of Protein Folding in Health and Disease

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