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The carboxysome is a bacterial micro-compartment (BMC) subtype that encapsulates enzymatic activities necessary for carbon fixation. Carboxysome shells are composed of a relatively complex cocktail of proteins, their precise number and identity being species dependent. Shell components can be classified in two structural families, the most abundant class associating as hexamers (BMC-H) that are supposed to be major players for regulating shell permeability. Up to recently, these proteins were proposed to associate as homo-oligomers. Genomic data, however, demonstrated the existence of paralogs coding for multiple shell subunits. Here, we studied cross-association compatibilities among BMC-H CcmK proteins of Synechocystis sp. PCC6803. Co-expression in Escherichia coli proved a consistent formation of hetero-hexamers combining CcmK1 and CcmK2 or, remarkably, CcmK3 and CcmK4 subunits. Unlike CcmK1/K2 hetero-hexamers, the stoichiometry of incorporation of CcmK3 in associations with CcmK4 was low. Cross-interactions implicating other combinations were weak, highlighting a structural segregation of the two groups that could relate to gene organization. Sequence analysis and structural models permitted the localization of interactions that would favor formation of CcmK3/K4 hetero-hexamers. The crystallization of these CcmK3/K4 associations conducted to the elucidation of a structure corresponding to the CcmK4 homo-hexamer. Yet, subunit exchange could not be demonstrated in vitro. Biophysical measurements showed that hetero-hexamers are thermally less stable than homo-hexamers, and impeded in forming larger assemblies. These novel findings are discussed within the context of reported data to propose a functional scenario in which minor CcmK3/K4 incorporation in shells would introduce sufficient local disorder as to allow shell remodeling necessary to adapt rapidly to environmental changes.
This article was published in the following journal.
Name: PloS one
In plants, rubisco activase (Rca) regulates rubisco by removing inhibitory molecules such as RuBP. In cyanobacteria, a homologous protein (activase-like cyanobacterial protein, ALC), contains a distin...
Pyridinearene macrocycles have previously shown unique host-guest properties in their capsular dimers including endo complexation of neutral molecules and exo complexation of anions. Here, we demonstr...
We report herein the synthesis of complex molecules containing furopyran cores through a gold(I)-catalyzed hetero-Diels-Alder cascade reaction. During this process, the diene and the dienophile are pr...
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The application of toxic solvents and additives is inevitable for most of the described protocols for F-labeling. Herein, a novel "green" procedure for nucleophilic aromatic radiofluorination of high...
Vacuum-formed retainers are clear or transparent retainers, that hold the teeth in the new position after active orthodontic treatment. These custom made appliances are becoming popular th...
The goal of the current study is to objectively measure intraoperative the initial thumb stability after trapezium removal when performing trapeziectomy, alone or in combination with suspe...
This study aims to evaluate the effect of a range of pre-formed orthoses on function of the foot and leg to generate technical data on how the individual insoles impact gait, distribution ...
The overall aim of the study is to investigate the Ponto wide implant considering; initial implant stability, stability over time, skin reaction and long term success when loaded at 3 week...
Whilst deep vein thrombosis (DVT) is common following traumatic brain injury (TBI), optimal timing and safety of pharmacological prophylaxis is uncertain. Paradoxically the harm associated...
Knobbed structures formed from and attached to plant roots, especially of LEGUMES, which result from symbiotic infection by nitrogen fixing bacteria such as RHIZOBIUM or FRANKIA. Root nodules are structures related to MYCORRHIZAE formed by symbiotic associations with fungi.
Monitoring of rate of occurrence of specific conditions to assess the stability or change in health levels of a population. It is also the study of disease rates in a specific cohort, geographic area, population subgroup, etc. to estimate trends in larger population. (From Last, Dictionary of Epidemiology, 2d ed)
Voluntary organizations which support educational programs and research in psychiatry with the objective of the promotion of mental health. An early association in the United States was founded as the National Committee for Mental Hygiene in 1909, became the Mental Health Association in 1976 and later the National Mental Health Association in 1980. State and local mental health associations in this country are chartered by the national organization and affiliated with it.
Sequences within RNA that regulate the processing, stability (RNA STABILITY) or translation (TRANSLATION, GENETIC) of RNA.
Bioinformatics is the application of computer software and hardware to the management of biological data to create useful information. Computers are used to gather, store, analyze and integrate biological and genetic information which can then be applied...