RESUMO
The roughly purified extract of E. coli proteins has been studied by cryoelectron microscopy, the class-sums containing 2D projections of two proteins (ß-galactosidase and 2-oxoglutarate dehydrogenase complex catalytic domain (ODC-CD)), identified in an extract by tandem mass spectrometry, have been distinguished. The structures of these proteins have been solved at near-atomic resolution. De novo simulation of the ODC-CD structure yielded an atomic model that revealed differences in the positions of some amino acid residues of the active center, in comparison with the known crystal structures.
RESUMO
Many cellular processes are associated with membrane remodeling. The BAR domain protein family plays a key role in the formation and detection of local membrane curvatures and in attracting other proteins, including the regulators of actin dynamics. Based on their structural and phylogenetic properties, BAR domains are divided into several groups which affect membrane in various ways and perform different functions in cells. However, recent studies have uncovered evidence of functional differences even within the same group. This review discusses the principles underlying the interactions of different groups of BAR domains, and their individual representatives ,with membranes.
RESUMO
Changes of chromatin structure require participation of chromatin remodeling factors (CRFs), which are ATP-dependent multisubunit complexes that change the structure of the nucleosome without covalently modifying its components. CRFs act together with other protein factors to regulate the extent of chromatin condensation. Four CRF families are currently distinguished based on their structural and biochemical characteristics: SWI/SNF, ISWI, Mi-2/CHD, and SWR/INO80. X-ray diffraction analysis and electron microscopy are the main methods to obtain structural information about macromolecules. CRFs are difficult to obtain in crystal because of their large sizes and structural heterogeneity, and transmission electron microscopy (TEM) is mostly employed in their structural studies. The review considers all structures obtained for CRFs by TEM and discusses several models of CRF-nucleosome interactions.
Assuntos
Adenosina Trifosfatases/química , Montagem e Desmontagem da Cromatina , Cromatina/química , Proteínas Cromossômicas não Histona/química , DNA Helicases/química , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/química , Fatores de Transcrição/química , ATPases Associadas a Diversas Atividades Celulares , Adenosina Trifosfatases/metabolismo , Animais , Proteínas Cromossômicas não Histona/metabolismo , Cristalografia por Raios X/métodos , DNA Helicases/metabolismo , Proteínas de Ligação a DNA , Humanos , Microscopia Eletrônica de Transmissão/métodos , Estrutura Quaternária de Proteína , Fatores de Transcrição/metabolismoRESUMO
The data on the structure of the chromosomal material of archaebacteria are reviewed. The results of comparison of amino acid sequences of archaebacterial chromosomal proteins with their eubacterial and eukaryotic counterparts are presented. The similarity and the difference in the structure and properties of chromosomal material of representatives of three evolutionary domains are discussed.
Assuntos
Archaea/genética , Cromossomos Bacterianos , Sequência de Aminoácidos , Proteínas de Bactérias/genética , Dados de Sequência Molecular , Homologia de Sequência de AminoácidosRESUMO
The phenomenon of high genetic variability in the extremely halophilic archaebacterium Hb. salinarium is reviewed. The role of IS elements and homologous recombination in frequent genetic rearrangements in this organism is discussed. A possible cause of high genetic variability of Hb. salinarium is considered.
