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Higher throughput methods to mount and collect data from multiple small and radiation-sensitive crystals are important to support challenging structural investigations using microfocus synchrotron beamlines. Furthermore, efficient sample-delivery methods are essential to carry out productive femtosecond crystallography experiments at X-ray free-electron laser (XFEL) sources such as the Linac Coherent Light Source (LCLS). To address these needs, a high-density sample grid useful as a scaffold for both crystal growth and diffraction data collection has been developed and utilized for efficient goniometer-based sample delivery at synchrotron and XFEL sources. A single grid contains 75 mounting ports and fits inside an SSRL cassette or uni-puck storage container. The use of grids with an SSRL cassette expands the cassette capacity up to 7200 samples. Grids may also be covered with a polymer film or sleeve for efficient room-temperature data collection from multiple samples. New automated routines have been incorporated into the Blu-Ice/DCSS experimental control system to support grids, including semi-automated grid alignment, fully automated positioning of grid ports, rastering and automated data collection. Specialized tools have been developed to support crystallization experiments on grids, including a universal adaptor, which allows grids to be filled by commercial liquid-handling robots, as well as incubation chambers, which support vapor-diffusion and lipidic cubic phase crystallization experiments. Experiments in which crystals were loaded into grids or grown on grids using liquid-handling robots and incubation chambers are described. Crystals were screened at LCLS-XPP and SSRL BL12-2 at room temperature and cryogenic temperatures.

Natural killer cells and cytotoxic T lymphocytes accomplish the critically important function of killing virus-infected and neoplastic cells. They do this by releasing the pore-forming protein perforin and granzyme proteases from cytoplasmic granules into the cleft formed between the abutting killer and target cell membranes. Perforin, a 67-kilodalton multidomain protein, oligomerizes to form pores that deliver the pro-apoptopic granzymes into the cytosol of the target cell (1-6). The importance of perforin is highlighted by the fatal consequences of congenital perforin deficiency, with more than 50 different perforin mutations linked to familial haemophagocytic lymphohistiocytosis (type 2 FHL) (7). Here we elucidate the mechanism of perforin pore formation by determining the X-ray crystal structure of monomeric murine perforin, together with a cryo-electron microscopy reconstruction of the entire perforin pore. Perforin is a thin 'key-shaped' molecule, comprising an amino-terminal membrane attack complex perforinlike (MACPF)/cholesterol dependent cytolysin (CDC) domain (8,9) followed by an epidermal growth factor (EGF) domain that, together with the extreme carboxy-terminal sequence, forms a central shelf-like structure. A C-terminal C2 domain mediates initial, [Ca.sup.2+]-dependent membrane binding. Most unexpectedly, however, electron microscopy reveals that the orientation of the perforin MACPF domain in the pore is inside-out relative to the subunit arrangement in CDCs (10,11). These data reveal remarkable flexibility in the mechanism of action of the conserved MACPF/CDC fold and provide new insights into how related immune defence molecules such as complement proteins assemble into pores., The sequence similarity between perforin and complement components C6-C9 of the membrane attack complex strongly suggests that two major branches of the mammalian immune system utilize a pore-forming MACPF fold [...]

The common pathogen Streptococcus pyogenes colonizes the human skin and tonsils and can invade underlying tissues. This requires the adhesion of S. pyogenes to host surface receptors mediated through adhesins. The laminin-binding protein Lbp has been suggested as an adhesin, specific for the human extracellular matrix protein laminin. Sequence alignments, however, indicate a relationship between Lbp and a family of bacterial metal-binding receptors. To further analyze the role of Lbp in S. pyogenes and its potential role in pathogenicity, Lbp has been crystallized, and its structure has been solved at a resolution of 2.45 [Angstrom] (R = 0.186; [R.sub.free] = 0.251). Lbp has the typical metal-binding receptor fold, comprising two globular [([beta]/[alpha]).sub.4] domains connected by a helical backbone. The two domains enclose the metal-binding site, which contains a zinc ion. The interaction of Lbp with laminin was further investigated and shown to be specific in vitro. Localization studies with antibodies specific for Lbp show that the protein is attached to the membrane. The data suggest that Lbp is primarily a zinc-binding protein, and we suggest that its interaction with laminin in vivo may be mediated via zinc bound to laminin.

Results indicate that L-threonine is an effective substrate for the nonribosomal peptide synthetase PvdD from Pseudomonas aeruginosa as determined by ATP-PPi exchange assays.

Plasminogen (Plg) is the zymogen form of the serine protease plasmin (Plm), and it plays a crucial role in fibrinolysis as well as wound healing, immunity, tissue remodeling and inflammation. Binding to the targets via the lysine-binding sites allows for Plg activation by plasminogen activators (PAs) present on the same target. Cellular uptake of fibrin degradation products leads to apoptosis, which represents one of the pathways for cross-talk between fibrinolysis and tissue remodeling. Therapeutic manipulation of Plm activity plays a vital role in the treatments of a range of diseases, whereas Plm inhibitors are used in trauma and surgeries as antifibrinolytic agents. Plm inhibitors are also used in conditions such as angioedema, menorrhagia and melasma. Here, we review the rationale for the further development of new Plm inhibitors, with a particular focus on the structural studies of the active site inhibitors of Plm. We compare the binding mode of different classes of inhibitors and comment on how it relates to their efficacy, as well as possible future developments. [ABSTRACT FROM AUTHOR]

The laminin-binding protein Lbp (Spy2007) from Streptococcus pyogenes (a group A streptococcus) mediates adhesion to the human basal lamina glycoprotein laminin. Accordingly, Lbp is essential in in vitro models of cell adhesion and invasion. However, the molecular and structural basis of laminin binding by bacteria remains unknown. Therefore, the lbp gene has been cloned for recombinant expression in Escherichia coli. Lbp has been purified and crystallized from 30%(w/v) PEG 1500 by the sitting-drop vapour-diffusion method. The crystals belonged to the monoclinic space group P21, with unit-cell parameters a = 42.62, b = 92.16, c = 70.61 Å, β = 106.27°, and diffracted to 2.5 Å resolution. [ABSTRACT FROM AUTHOR]

Myo-inositol oxygenase (MIOX) catalyzes the novel oxidative cleavage of myo-inositol (MI) and its epimerd- chiro inositol (DCI) tod-glucuronate. MIOX utilizes an FeII/FeIII binuclear iron centre for the dioxygen-dependent cleavage of the C1—C6 bond in MI. Despite its key role in inositol metabolism, the structural basis of its unique four-electron oxidation mechanism and its substrate specificity remain unknown. In order to answer these questions and to facilitate the use of this key enzyme for the development of new therapeutic strategies for diabetes, the mouse enzyme has been cloned, expressed in Escherichia coli, purified and crystallized from 4.4 M sodium formate. The crystals belong to space group P212121, with unit-cell parameters a = 44.87, b = 77.26, c = 84.84 Å, and diffract to 2.8 Å resolution. [ABSTRACT FROM AUTHOR]

Myo-inositol oxygenase (MIOX) catalyzes the novel oxidative cleavage of myo-inositol (MI) and its epimer D-chiro inositol (DCI) to D-glucuronate. MIOX utilizes an Fe(II)/Fe(III) binuclear iron centre for the dioxygen-dependent cleavage of the C1-C6 bond in MI. Despite its key role in inositol metabolism, the structural basis of its unique four-electron oxidation mechanism and its substrate specificity remain unknown. In order to answer these questions and to facilitate the use of this key enzyme for the development of new therapeutic strategies for diabetes, the mouse enzyme has been cloned, expressed in Escherichia coli, purified and crystallized from 4.4 M sodium formate. The crystals belong to space group P2(1)2(1)2(1), with unit-cell parameters a = 44.87, b = 77.26, c = 84.84 angstroms, and diffract to 2.8 angstroms resolution.