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Newly folded substrates inside the molecular cage of the HtrA chaperone DegQ.

ABSTRACT: The HtrA protein family combines chaperone and protease activities and is essential for protein quality control in many organisms. Whereas the mechanisms underlying the proteolytic function of HtrA proteins are well characterized, their chaperone activity remains poorly understood. Here we describe cryo-EM structures of Escherichia coli DegQ in its 12- and 24-mer states in complex with model substrates, providing a structural model of HtrA chaperone action. Up to six lysozyme substrates bind inside the DegQ 12-mer cage and are visualized in a close-to-native state. An asymmetric reconstruction reveals the binding of a well-ordered lysozyme to four DegQ protomers. DegQ PDZ domains are located adjacent to substrate density and their presence is required for chaperone activity. The substrate-interacting regions appear conserved in 12- and 24-mer cages, suggesting a common mechanism of chaperone function.

SUBMITTER: Malet H

PROVIDER: S-EPMC3272482 | biostudies-literature | 2012 Jan

REPOSITORIES: biostudies-literature

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Newly folded substrates inside the molecular cage of the HtrA chaperone DegQ.

Malet Hélène H Canellas Flavia F Sawa Justyna J Yan Jun J Thalassinos Konstantinos K Ehrmann Michael M Clausen Tim T Saibil Helen R HR

Nature structural & molecular biology 20120115 2

The HtrA protein family combines chaperone and protease activities and is essential for protein quality control in many organisms. Whereas the mechanisms underlying the proteolytic function of HtrA proteins are well characterized, their chaperone activity remains poorly understood. Here we describe cryo-EM structures of Escherichia coli DegQ in its 12- and 24-mer states in complex with model substrates, providing a structural model of HtrA chaperone action. Up to six lysozyme substrates bind ins ...[more]

PMID: 22245966

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Project description:Computational experiments on a novel crystal (Bharadwaj et al. Cryst. Growth Des. 2019, 19, 369-375) having a series of seven host-guest complexes (HGCs) where the host species belong to the family of a novel bispyrazole organic cryptand (BPOC) and their structural, stability, and the electronic feature analyses have been reported using the quantum chemical calculation approach. This report systematically unravels an inclusive theory-based experiment on the well-known guest solvents (S) like halocarbon solvents [CCl4, CHCl3/CHCl3' (two orientations), CH2Cl2 , C2H4Cl2 , C2H4Br2 , and C2HCl3 ] and a few model chlorofluorocarbons (CFCs) (CClF3 , CCl2F2 , and CCl3F) trapped inside the host (BPOC) cryptand, which are the crux in forming the structures of biological and supramolecular systems. Using the implicitly dispersion-corrected DFT (M06-2X/6-31G*) approach, the BPOC molecular cage and its host-guest capabilities were evaluated for the encapsulation of the above said halocarbon solvents as well as the CFC models. The encapsulated C2H4Br2 solvent inside the BPOC cage is found to be the most stable among all the HGCs; however, common in the solid phase, similar binary complexes have not been formerly examined in any gas/solvent-phase studies of the BPOC host species. Moreover, very interestingly, the stability pattern of the host-guest complexes enhances for the CFC models when the number of Cl atoms is increased. As the halogenated solvents through halogen and H-bonding are very decisive in understanding and controlling chemical reactions, the NCI-plots support the presence of the halogen bonding (C-Cl/Br···π) and H-bonding (C-H···π) interactions playing an imperative role in stabilizing the guests (solvents) inside the hydrophobic cavity. To get more insights, the HOMO-LUMO and MESP plots as well as natural population analyses have also been highlighted. This theoretical study portrays an inclusive information about the structural, stability, and electronic feature analyses of the host-guest assemblies consisting of the halogen and H-bonding interactions at the atomic level where the influences of such halocarbon solvents play crucial roles in comprehending and managing chemical reactions.

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Newly folded substrates inside the molecular cage of the HtrA chaperone DegQ.

Publications

Newly folded substrates inside the molecular cage of the HtrA chaperone DegQ.

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