Continuous development in macromolecular crystallography with CCP4.

The evolution of the Collaborative Computational Project No. 4 (CCP4) has been described in a new article by Agirre et al. [(2023).

Structural basis of the regulatory mechanism of the plant CIPK family of protein kinases controlling ion homeostasis and abiotic stress.

Plant cells have developed specific protective molecular machinery against environmental stresses. The family of CBL-interacting protein kinases (CIPK) and their interacting activators, the calcium sensors calcineurin B-like (CBLs), work together to decode calcium signals elicited by stress situations. The molecular basis of biological activation of CIPKs relies on the calcium-dependent interaction of a self-inhibitory NAF motif with a particular CBL, the phosphorylation of the activation loop by upstream kinases, and the subsequent phosphorylation of the CBL by the CIPK.

Structural basis of PcsB-mediated cell separation in Streptococcus pneumoniae.

Separation of daughter cells during bacterial cell division requires splitting of the septal cross wall by peptidoglycan hydrolases. In Streptococcus pneumoniae, PcsB is predicted to perform this operation. Recent evidence shows that PcsB is recruited to the septum by the transmembrane FtsEX complex, and that this complex is required for cell division.

Heteroresistance to fosfomycin is predominant in Streptococcus pneumoniae and depends on the murA1 gene.

Fosfomycin targets the first step of peptidoglycan biosynthesis in Streptococcus pneumoniae catalyzed by UDP-N-acetylglucosamine enolpyruvyltransferase (MurA1). We investigated whether heteroresistance to fosfomycin occurs in S. pneumoniae.

Structural Biology of a Major Signaling Network that Regulates Plant Abiotic Stress: The CBL-CIPK Mediated Pathway.

The Arabidopsis SOS2 family of twenty-six protein kinases (CIPKs), their interacting activators, the SOS3 family of ten calcium-binding proteins (CBLs) and protein phosphatases type 2C (PP2C), function together in decoding calcium signals elicited by different environmental stimuli. Biochemical data suggest that stable CBL-CIPK or CIPK-PP2C complexes may be regulating the activity of various substrates controlling ion homeostasis. The available structural information provides a general regulatory mechanism in which calcium perception by CBLs and kinase activation is coupled.

Crystallization and preliminary crystallographic analysis of a C2 protein from Arabidopsis thaliana.

An uncharacterized protein from Arabidopsis thaliana consisting of a single C2 domain (At3g17980) was cloned into the pETM11 vector and expressed in Escherichia coli, allowing purification to homogeneity in a single chromatographic step. Good-quality diffracting crystals were obtained using vapour-diffusion techniques. The crystals diffracted to 2.

Preliminary X-ray analysis of twinned crystals of the Q88Y25_Lacpl esterase from Lactobacillus plantarum WCFS1.

Q88Y25_Lacpl is an esterase produced by the lactic acid bacterium Lactobacillus plantarum WCFS1 that shows amino-acid sequence similarity to carboxylesterases from the hormone-sensitive lipase family, in particular the AFEST esterase from the archaeon Archaeoglobus fulgidus and the hyperthermophilic esterase EstEI isolated from a metagenomic library. N-terminally His(6)-tagged Q88Y25_Lacpl has been overexpressed in Escherichia coli BL21 (DE3) cells, purified and crystallized at 291 K using the hanging-drop vapour-diffusion method. Mass spectrometry was used to determine the purity and homogeneity of the enzyme.

The structure of Arabidopsis thaliana OST1 provides insights into the kinase regulation mechanism in response to osmotic stress.

SnRK [SNF1 (sucrose non-fermenting-1)-related protein kinase] 2.6 [open stomata 1 (OST1)] is well characterized at molecular and physiological levels to control stomata closure in response to water-deficit stress. OST1 is a member of a family of 10 protein kinases from Arabidopsis thaliana (SnRK2) that integrates abscisic acid (ABA)-dependent and ABA-independent signals to coordinate the cell response to osmotic stress.

Crystal structures of bacterial peptidoglycan amidase AmpD and an unprecedented activation mechanism.

AmpD is a cytoplasmic peptidoglycan (PG) amidase involved in bacterial cell-wall recycling and in induction of β-lactamase, a key enzyme of β-lactam antibiotic resistance. AmpD belongs to the amidase_2 family that includes zinc-dependent amidases and the peptidoglycan-recognition proteins (PGRPs), highly conserved pattern-recognition molecules of the immune system. Crystal structures of Citrobacter freundii AmpD were solved in this study for the apoenzyme, for the holoenzyme at two different pH values, and for the complex with the reaction products, providing insights into the PG recognition and the catalytic process.

SnRK2.6/OST1 from Arabidopsis thaliana: cloning, expression, purification, crystallization and preliminary X-ray analysis of K50N and D160A mutants.

The SnRK2.6 (SNF1-related kinase 2.6) gene from Arabidopsis thaliana encodes the serine/threonine protein kinase SnRK2.

Insights into pneumococcal fratricide from the crystal structures of the modular killing factor LytC.

The first structure of a pneumococcal autolysin, that of the LytC lysozyme, has been solved in ternary complex with choline and a pneumococcal peptidoglycan (PG) fragment. The active site of the hydrolase module is not fully exposed but is oriented toward the choline-binding module, which accounts for its unique in vivo features in PG hydrolysis, its activation and its regulatory mechanisms. Because of the unusual hook-shaped conformation of the multimodular protein, it is only able to hydrolyze non-cross-linked PG chains, an assertion validated by additional experiments.

Crystallization of the pneumococcal autolysin LytC: in-house phasing using novel lanthanide complexes.

LytC, one of the major autolysins from the human pathogen Streptococcus pneumoniae, has been crystallized as needles by the hanging-drop technique using 10%(w/v) PEG 3350 as precipitant and 10 mM HEPES pH 7.5. LytC crystals were quickly soaked in mother liquor containing 2 mM of the complex Gd-HPDO3A to produce derivatized crystals (LytC(Gd-HPDO3A)).

Activation of bacterial thermoalkalophilic lipases is spurred by dramatic structural rearrangements.

The bacterial thermoalkalophilic lipases that hydrolyze saturated fatty acids at 60-75 degrees C and pH 8-10 are grouped as the lipase family I.5. We report here the crystal structure of the lipase from Geobacillus thermocatenulatus, the first structure of a member of the lipase family I.

Crystallization and preliminary X-ray diffraction studies of the BTL2 lipase from the extremophilic microorganism Bacillus thermocatenulatus.

Bacillus thermocatenulatus lipase 2 (BTL2) is a thermoalkalophilic lipase that has been reported as an enantioselective biocatalyst for diverse reactions and that heads a group of enzymes that share high resistance towards many inactivation agents (heat, organic solvents, pH etc.). This makes BTL2 an important research target because of its potential industrial applications.

The complex between SOS3 and SOS2 regulatory domain from Arabidopsis thaliana: cloning, expression, purification, crystallization and preliminary X-ray analysis.

The salt-tolerance genes SOS3 (salt overly sensitive 3) and SOS2 (salt overly sensitive 2) regulatory domain of Arabidopsis thaliana were cloned into a polycistronic plasmid and the protein complex was expressed in Escherichia coli, allowing purification to homogeneity in three chromatographic steps. Crystals were grown using vapour-diffusion techniques. The crystals belonged to space group P2(1)2(1)2(1), with unit-cell parameters a = 44.

Elucidation of the molecular recognition of bacterial cell wall by modular pneumococcal phage endolysin CPL-1.

Pneumococcal bacteriophage-encoded lysins are modular proteins that have been shown to act as enzymatic antimicrobial agents (enzybiotics) in treatment of streptococcal infections. The first x-ray crystal structures of the Cpl-1 lysin, encoded by the pneumococcal phage Cp-1, in complex with three bacterial cell wall peptidoglycan (PG) analogues are reported herein. The Cpl-1 structure is folded in two well defined modules, one responsible for anchoring to the pneumococcal cell wall and the other, a catalytic module, that hydrolyzes the PG.

The structure of the C-terminal domain of the protein kinase AtSOS2 bound to the calcium sensor AtSOS3.

The plant SOS2 family of protein kinases and their interacting activators, the SOS3 family of calcium-binding proteins, function together in decoding calcium signals elicited by different environmental stimuli. SOS2 is activated by Ca-SOS3 and subsequently phosphorylates the ion transporter SOS1 to bring about cellular ion homeostasis under salt stress. In addition to possessing the kinase activity, members of the SOS2 family of protein kinases can bind to protein phosphatase 2Cs.

Insights into pneumococcal pathogenesis from the crystal structure of the modular teichoic acid phosphorylcholine esterase Pce.

Phosphorylcholine, a specific component of the pneumococcal cell wall, is crucial in pathogenesis. It directly binds to the human platelet-activating factor (PAF) receptor and acts as a docking station for the family of surface-located choline-binding proteins (CBP). The first structure of a complete pneumococcal CBP, Pce (or CbpE), has been solved in complex with the reaction product and choline analogs.

Structural analysis of the Laetiporus sulphureus hemolytic pore-forming lectin in complex with sugars.

LSL is a lectin produced by the parasitic mushroom Laetiporus sulphureus, which exhibits hemolytic and hemagglutinating activities. Here, we report the crystal structure of LSL refined to 2.6-A resolution determined by the single isomorphous replacement method with the anomalous scatter (SIRAS) signal of a platinum derivative.

The structure of the Arabidopsis thaliana SOS3: molecular mechanism of sensing calcium for salt stress response.

The Arabidopsis thaliana SOS3 gene encodes a calcium sensor that is required for plant salt tolerance. The SOS3 protein binds to and activates the self-inhibited SOS2 protein kinase, which mediates the expression and activities of various transporters important for ion homeostasis under salt stress. SOS3 belongs to a unique family of calcium-binding proteins that contain two pairs of EF hand motifs with four putative metal-binding sites.

Crystal structure of rat liver betaine homocysteine s-methyltransferase reveals new oligomerization features and conformational changes upon substrate binding.

Betaine homocysteine S-methyltransferase (BHMT) is one of the two enzymes known to methylate homocysteine to generate methionine in the liver. It presents a Zn(2+) atom linked to three essential Cys residues. The crystal structure of rat liver BHMT has been solved at 2.

Crystal and electron microscopy structures of sticholysin II actinoporin reveal insights into the mechanism of membrane pore formation.

Sticholysin II (StnII) is a pore-forming protein (PFP) produced by the sea anemone Stichodactyla helianthus. We found out that StnII exists in a monomeric soluble state but forms tetramers in the presence of a lipidic interface. Both structures have been independently determined at 1.

Structural basis for selective recognition of pneumococcal cell wall by modular endolysin from phage Cp-1.

Pneumococcal bacteriophage-encoded lysins are modular choline binding proteins that have been shown to act as enzymatic antimicrobial agents (enzybiotics) against streptococcal infections. Here we present the crystal structures of the free and choline bound states of the Cpl-1 lysin, encoded by the pneumococcal phage Cp-1. While the catalytic module displays an irregular (beta/alpha)(5)beta(3) barrel, the cell wall-anchoring module is formed by six similar choline binding repeats (ChBrs), arranged into two different structural regions: a left-handed superhelical domain configuring two choline binding sites, and a beta sheet domain that contributes in bringing together the whole structure.