Crystal structure of Campylobacter jejuni lipoprotein Cj1090c

In Gram-negative bacteria, lipopolysaccharide (LPS) is an essential component of the asymmetric outer membrane (OM). LptE is an OM lipoprotein that forms a complex with the β-barrel OM protein, LptD. Incorporation of LPS into the OM outer leaflet is essential for bacterial viability, and mediated by the LptD/E complex. The genome of Campylobacter jejuni, a major foodborne pathogen, contains over 20 putative lipoproteins including Cj1090c. Here, we report the crystal structure of Cj1090c at 2.4 Å resolution, revealing structural evidence for LptE in C. jejuni. The analysis of this crystal structure, along with the genomic context, allows us to propose the C. jejuni LPS transport system for the first time, and permits for discussion of the features of the LptD/E complex of C. jejuni.

Donor-π-donor type hole transporting materials: marked π-bridge effects on optoelectronic properties, solid-state structure, and perovskite solar cell efficiency

Donor–π-bridge–donor type oligomers (D–π–D) have been studied intensively as active materials for organic optoelectronic devices.

Donor–π-bridge–donor type oligomers (D–π–D) have been studied intensively as active materials for organic optoelectronic devices. In this study, we introduce three new D–π–D type organic semiconductors incorporating thiophene or thienothiophene with two electron-rich TPA units, which can be easily synthesized from commercially available materials. A thorough comparison of their optoelectronic and structural properties was conducted, revealing the strong influence of the extent of longitudinal π-bridge conjugation on both the solid structure of the organic semiconductive materials and their photovoltaic performance when applied as hole transporting materials (HTM) in perovskite solar cells. Single-crystal measurements and time-resolved photoluminescence (TRPL) studies indicate that these coplanar donor–π–donor type HTMs could be promising alternatives to state-of-the-art spiro-OMeTAD, due to the multiple intermolecular short contacts as charge transporting channels and efficient charge extraction properties from the perovskite layer. The optimized devices with PEH-9 exhibited an impressive PCE of 16.9% under standard global AM 1.5 illumination with minimized hysteretic behaviour, which is comparable to that of devices using spiro-OMeTAD under similar conditions. Ambient stability after 400 h revealed that 93% of the energy conversion efficiency was retained for PEH-9, indicating that the devices had good long-term stability.

Crystal structure of the Campylobacter jejuni Cj0090 protein reveals a novel variant of the immunoglobulin fold among bacterial lipoproteins

Bacterial lipoproteins play an important role in bacterial pathogenesis and physiology. The genome of Campylobacter jejuni, a major foodborn pathogen, is predicted to contain over 20 lipoproteins. However, the functions of the majority of C. jejuni lipoproteins remain unknown. The Cj0090 protein is encoded by a lipoprotein operon composed of cj0089, cj0090, and cj0091. Here, we report the crystal structure of Cj0090 at 1.9 Å resolution, revealing a novel variant of the immunoglobulin fold with β-sandwich architecture. The structure suggests that Cj0090 may be involved in protein-protein interactions, consistent with a possible role for bacterial lipoproteins.

Crystal structure of JlpA, a surface-exposed lipoprotein adhesin of Campylobacter jejuni

The Campylobacter jejuni JlpA protein is a surface-exposed lipoprotein that was discovered as an adhesin promoting interaction with host epithelium cells, an early critical step in the pathogenesis of C. jejuni disease. Increasing evidence ascertained that JlpA is antigenic, indicating a role of JlpA in immune response during the infectious process. Here, we report the crystal structure of JlpA at 2.7Å resolution, revealing a catcher's mitt shaped unclosed half β-barrel. Although the apparent architecture of JlpA is somewhat reminiscent of other bacterial lipoproteins such as LolB, the topology of JlpA is unique among the bacterial surface proteins reported to date and therefore JlpA represents a novel bacterial cell surface lipoprotein. The concave face of the structure results in an unusually large hydrophobic basin with a localized acidic pocket, suggesting a possibility that JlpA may accommodate multiple ligands. Therefore, the structure provides framework for determining the molecular function of JlpA and new strategies for the rational design of small molecule inhibitors efficiently targeting JlpA.

The Actinobacillus pleuropneumoniae HMW1C-like glycosyltransferase mediates N-linked glycosylation of the Haemophilus influenzae HMW1 adhesin

The Haemophilus influenzae HMW1 adhesin is an important virulence exoprotein that is secreted via the two-partner secretion pathway and is glycosylated at multiple asparagine residues in consensus N-linked sequons. Unlike the heavily branched glycans found in eukaryotic N-linked glycoproteins, the modifying glycan structures in HMW1 are mono-hexoses or di-hexoses. Recent work demonstrated that the H. influenzae HMW1C protein is the glycosyltransferase responsible for transferring glucose and galactose to the acceptor sites of HMW1. An Actinobacillus pleuropneumoniae protein designated ApHMW1C shares high-level homology with HMW1C and has been assigned to the GT41 family, which otherwise contains only O-glycosyltransferases. In this study, we demonstrated that ApHMW1C has N-glycosyltransferase activity and is able to transfer glucose and galactose to known asparagine sites in HMW1. In addition, we found that ApHMW1C is able to complement a deficiency of HMW1C and mediate HMW1 glycosylation and adhesive activity in whole bacteria. Initial structure-function studies suggested that ApHMW1C consists of two domains, including a 15-kDa N-terminal domain and a 55-kDa C-terminal domain harboring glycosyltransferase activity. These findings suggest a new subfamily of HMW1C-like glycosyltransferases distinct from other GT41 family O-glycosyltransferases.

Structure of a sigma28-regulated nonflagellar virulence protein from Campylobacter jejuni

Campylobacter jejuni, a Gram-negative motile bacterium, is a leading cause of human gastrointestinal infections. Although the mechanism of C.jejuni-mediated enteritis appears to be multifactorial, flagella play complex roles in the virulence of this human pathogen. Cj0977 is a recently identified virulence factor in C. jejuni and is expressed by a sigma(28) promoter that controls late genes in the flagellar regulon. A Cj0977 mutant strain is fully motile but significantly reduced in the invasion of intestinal epithelial cells in vitro. Here, we report the crystal structure of the major structural domain of Cj0977, which reveals a homodimeric "hot-dog" fold architecture. Of note, the characteristic hot-dog fold has been found in various coenzyme A (CoA) compound binding proteins with numerous oligomeric states. Structural comparison with other known hot-dog fold proteins locates a putative binding site for an acyl-CoA compound in the Cj0977 protein. Structure-based site-directed mutagenesis followed by invasion assays indicates that key residues in the putative binding site are indeed essential for the Cj0977 virulence function, suggesting a possible function of Cj0977 as an acyl-CoA binding regulatory protein.

Effect of Na-hyaluronan on stromal and endothelial healing in experimental corneal alkali wounds

The healing of stroma and endothelium after a standardized corneal alkali wound was evaluated in sodium-hyaluronan (Na-HA)-treated eyes. Alkali wounds were produced in one eye of each rabbit by applying a 5.5-mm round filter paper soaked in 1 N NaOH onto the central cornea for 60 s. Eyes were then treated with either 1% Na-HA (the treatment group) or phosphate-buffered saline (the control group) 4 times per day for 3 weeks. Endothelial wound morphometry was performed after alizarin red and trypan blue staining, while stromal healing was assessed by counting polymorphonuclear leukocytes (PMNs) and keratocytes in the central and marginal wound areas. During the early healing period the stroma treated with Na-HA had less PMNs than that of the control group. The size of the endothelial defect area measured 5 days after injury was significantly smaller in the Na-HA group than in the control corneas. The present findings indicate that topically applied 1% Na-HA affects stromal and endothelial healing during the early repair process after corneal alkali wounds.

Sternal closure with resorbable synthetic suture material in children

The use of resorbable sutures for sternal closure after median sternotomy in children has developed to a clinically routine procedure. Since there is no follow-up study so far about the influence of these synthetic sutures on sternal stability, wound healing, and compatibility in children, we evaluated the use of polydioxanon (PDS) cord in children particularly regarding those properties. In 59 children (weighing up to 30 kg) we could show that the use of synthetic resorbable materials (Vicryl 4/0, PDS) allows a complication-free stability of the sternum, good wound healing, and very good compatibility. It is concluded that the use of PDS cord is a suitable and reliable method for sternal closure with good clinical results.

Experience with anatomical correction of transposition of the great arteries (TGA)

During the past seven years, 102 patients with TGA have been operated on using the switch operation. Overall early mortality was 5.9%, late mortality 2.%. Sixty-three newborns had an intact septum and were corrected between the 3th and 35th day after birth, 39 had a ventricular septal defect and/or associated anomalies. All operations were carried out under ECC and deep hypothermia. Myocardial function was recorded intraoperatively by using sonomicrometry. The data demonstrate that adaptation of the left ventricle to the new load conditions should be supported by drugs providing inotropic stimulation and afterload reduction. Mean follow-up time is 32.5 months, no rhythm problems have been recorded during that period, a few children revealed trivial pulmonary or aortic valve stenosis and/or incompetence. The switch operation permits good early results for newborns with TGA and intact septum and TGA with VSD. A decade has to pass in order to judge the long-term results.