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Recent advances in ab initio direct methods have enabled the solution of crystal structures of small proteins from native X-ray data alone, that is, without the use of fragments of known structure or the need to prepare heavy-atom or selenomethionine derivatives, provided that the data are available to atomic resolution. These methods are also proving to be(More)
Ab initio macromolecular phasing has been so far limited to small proteins diffracting at atomic resolution (beyond 1.2 A) unless heavy atoms are present. We describe a general ab initio phasing method for 2 A data, based on combination of localizing model fragments such as small á-helices with Phaser and density modification with SHELXE. We implemented(More)
RepB initiates plasmid rolling-circle replication by binding to a triple 11-bp direct repeat (bind locus) and cleaving the DNA at a specific distant site located in a hairpin loop within the nic locus of the origin. The structure of native full-length RepB reveals a hexameric ring molecule, where each protomer has two domains. The origin-binding and(More)
Improved data quality now makes it feasible to exploit the weak anomalous signal derived only from the sulfurs inherent to the protein or in particular from halide ions incorporated by soaking. The latter technique requires the location of a high number of partially occupied halide sites. This number appears to be roughly proportional to the exposed protein(More)
The crystal structure of the first endolytic peptidoglycan lytic transglycosylase MltE from Escherichia coli is reported herein. The degradative activity of this enzyme initiates the process of cell wall recycling, which is an integral event in the bacterial existence. The structure sheds light on how MltE recognizes its substrate, the cell wall(More)
Vaults are ubiquitous ribonucleoprotein complexes involved in a diversity of cellular processes, including multidrug resistance, transport mechanisms and signal transmission. The vault particle shows a barrel-shaped structure organized in two identical moieties, each consisting of 39 copies of the major vault protein MVP. Earlier data indicated that vault(More)
Since its release in September 2009, the structure-solution program ARCIMBOLDO, based on the combination of locating small model fragments such as polyalanine α-helices with density modification with the program SHELXE in a multisolution frame, has evolved to incorporate other sources of stereochemical or experimental information. Fragments that are more(More)
Methicillin resistance in Staphylococcus aureus is elicited by the MecI-MecR1-MecA axis encoded by the mec locus. Recently, MecR2 was also identified as a regulator of mec through binding of the methicillin repressor, MecI. Here we show that plasmid-encoded full-length MecR2 restores resistance in a sensitive S. aureus mecR2 deletion mutant of the resistant(More)
Ab initio phasing of macromolecular structures, from the native intensities alone with no experimental phase information or previous particular structural knowledge, has been the object of a long quest, limited by two main barriers: structure size and resolution of the data. Current approaches to extend the scope of ab initio phasing include use of the(More)
We describe an algorithm for phasing protein crystal X-ray diffraction data that identifies, retrieves, refines and exploits general tertiary structural information from small fragments available in the Protein Data Bank. The algorithm successfully phased, through unspecific molecular replacement combined with density modification, all-helical, mixed(More)