Sequence analysis and biological characterization of virulent Avian avulavirus 1 isolated from asymptomatic migratory fowl.

Continuous monitoring and surveillance of avian avulaviruses (AAvVs) in water/migratory fowl is imperative to ascertain the evolutionary dynamics of these viruses. Here, we report genomic and amino acid characteristics of two AAvVs strains isolated from asymptomatic waterfowl (Anas carolinensis). Sequence characteristics including the presence of virulent motif (112RRQKR↓F117) and biological assessment confirmed the virulent nature of study isolates. Phylogenetic analysis of complete fusion (F) and hemagglutinin-neuraminidase (HN), and hyper-variable region of F gene revealed clustering of both strains within genotype VII and sub-genotype VIIi. The inferred residue analysis of complete F and HN genes revealed a number of substitutions in functionally and structurally important motif/s compared to reference strains of each genotype (I-XI). This study concludes an evolutionary nature of avian avulavaris 1 (AAvV-1), ascertaining continuous surveillance of migratory fowl to better elucidate their infection, epidemiology and subsequent impacts on commercial and backyard poultry. Keywords: virulent AAvV-1; migratory fowl; genetic characterization; evolutionary analysis; Pakistan.

Seroprevalence of Bluetongue Virus in small ruminants in Balochistan province, Pakistan.

Bluetongue (BT), caused by bluetongue virus (BTV), is a vector-borne disease of small ruminants that has the potential to spread across international borders. Despite large populations of susceptible animals and borders with BTV endemic countries, little is known of the disease burden and prevalent serotypes in the province of Balochistan in Pakistan. We conducted a cross-sectional study to determine seroconversion and prevalent serotypes in selected districts of the province using a competitive enzyme-linked immunosorbent assay (cELISA) and real-time polymerase chain reaction (RT-PCR). Sera (n = 876) were collected from clinically healthy sheep and goats originating from the districts of Quetta (n = 300), Mastung (n = 201), Killa Saifullah (n = 75) and Kech (n = 300). None of the study herds (n = 97) were seronegative for BTV, and at the individual level, the overall prevalence of BTV seroconversion was 47.26% (n = 414/876, 95% CI = 43.92%-50.63%). A higher percentage of goats (50.87%, 95% CI = 45.99%-55.73%) were seropositive for anti-VP7 immunoglobulins (IgG) than sheep (44.21%, 95% CI = 39.81%-48.70%). Odds ratios of seroconversion for goats were associated with breed type (χ2  = 16.84, p = .01), parity (χ2  = 23.66, p = .00) and presence of vector (χ2  = 2.63, p = .10), whereas for sheep, it was associated with breed type (χ2  = 13.80, p = .01) and parity (χ2  = 53.40, p = .00). Serotype 8 was the most prevalent (26.82%, 95% CI = 14.75%-43.21%) followed by an equal prevalence of serotypes 2 and 9 (7.31%, 95% CI = 1.91%-21.01%). To the best of our knowledge, this is the first study conducted in Balochistan province and the results indicate that there is a necessity to initiate intervention strategies to control BT disease burden not only in this region of Pakistan but also in adjacent areas of the neighbouring countries, Iran and Afghanistan.

Exploring nicotinamide cofactor promiscuity in NAD(P)H-dependent flavin containing monooxygenases (FMOs) using natural variation within the phosphate binding loop. Structure and activity of FMOs from Cellvibrio sp. BR and Pseudomonas stutzeri NF13.

Flavin-containing monooxygenases (FMOs) catalyse asymmetric oxidation reactions that have potential for preparative organic synthesis, but most use the more expensive, phosphorylated nicotinamide cofactor NADPH to reduce FAD to FADH2 prior to formation of the (hydro)peroxy intermediate required for substrate oxygenation. A comparison of the structures of NADPH-dependent FMO from Methylophaga aminisulfidivorans (mFMO) and SMFMO from Stenotrophomonas maltophilia, which is able to use both NADPH and NADH, suggested that the promiscuity of the latter enzyme may be due in part to the substitution of an Arg-Thr couple in the NADPH phosphate recognition site in mFMO, for a Gln-His couple in SMFMO (Jensen et al., 2012, Chembiochem, 13, 872-878). Natural variation within the phosphate binding region, and its influence on nicotinamide cofactor promiscuity, was explored through the cloning, expression, characterisation and structural studies of FMOs from Cellvibrio sp. BR (CFMO) and Pseudomonas stutzeri NF13 (PSFMO), which possess Thr-Ser and Gln-Glu in the putative phosphate recognition positions, respectively. CFMO and PSFMO displayed 5- and 1.5-fold greater activity, respectively, than SMFMO for the reduction of FAD with NADH, and were also cofactor promiscuous, displaying a ratio of activity with NADH:NADPH of 1.7:1 and 1:1.3, respectively. The structures of CFMO and PSFMO revealed the context of the phosphate binding loop in each case, and also clarified the structure of the mobile helix-loop-helix motif that appears to shield the FAD-binding pocket from bulk solvent in this class of FMOs, a feature that was absent from the structure of SMFMO.

Mutations of an NAD(P)H-dependent flavoprotein monooxygenase that influence cofactor promiscuity and enantioselectivity.

The flavoprotein monooxygenase (FPMO) from Stenotrophomonas maltophilia (SMFMO, Uniprot: B2FLR2) catalyses the asymmetric oxidation of thioethers and is unusual amongst FPMOs in its ability to use the non-phosphorylated cofactor NADH, as well as NADPH, for the reduction of the FAD coenzyme. In order to explore the basis for cofactor promiscuity, structure-guided mutation of two residues in the cofactor binding site, Gln193 and His194, in SMFMO were performed in an attempt to imitate the cofactor binding site of the NADPH-dependent FMO from Methylophaga aminisulfidivorans sp. SK1 (mFMO), in which structurally homologous residues Arg234 and Thr235 bind the NADPH 2'-ribose phosphate. Mutation of His194 to threonine proved most significant, with a switch in specificity from NADH to NADPH [(k cat/K m NADH)/k cat/K m NADPH) from 1.5:1 to 1:3.5, mostly as a result of a reduced K m for NADPH of approximately sevenfold in the His194Thr mutant. The structure of the Gln193Arg/His194Thr mutant revealed no substantial changes in the backbone of the enzyme or orientation of side chains resulting from mutation. Mutation of Phe52, in the vicinity of FAD, and which in mFMO is an asparagine thought to be responsible for flavin hydroperoxide stabilisation, is, in SMFMO, a determinant of enantioselectivity in sulfoxidation. Mutation of Phe52 to valine resulted in a mutant that transformed para-tolyl methyl sulfide into the (S)-sulfoxide with 32% e.e., compared to 25% (R)- for the wild type. These results shed further light both on the cofactor specificity of FPMOs, and their determinants of enantioselectivity, with a view to informing engineering studies of FPMOs in the future.

Genome sequence of Stenotrophomonas maltophilia PML168, which displays Baeyer-Villiger monooxygenase activity.

Stenotrophomonas maltophilia PML168 was isolated from Wembury Beach on the English Coast from a rock pool following growth and selection on agar plates. Here we present the permanent draft genome sequence, which has allowed prediction of function for several genes encoding enzymes relevant to industrial biotechnology, including a novel flavoprotein monooxygenase.

Knee arthropathy: when things go wrong.

Joint bleeding, or haemarthrosis, is the most common type of bleeding episode experienced by individuals with haemophilia A and B. This leads to changes within the joints, including synovial proliferation, which results in further bleeding and chronic synovitis. Blood in the joint can also directly damage the cartilage, and with repeated bleeding, there is progressive destruction of both cartilage and bone. The end result is known as haemophilic arthropathy which is characterized by pain, stiffness and deformity. The joint most commonly affected is the knee. Haemophilic arthropathy can be prevented through regular prophylaxis and physiotherapy. However, when necessary, there are multiple surgical and non-surgical options available. These procedures are indicated to improve the joint function and quality of life for haemophilic patients worldwide. In this review, the role of surgical and non-surgical treatment of advanced knee arthropathy and its complications will be described.

A flavoprotein monooxygenase that catalyses a Baeyer-Villiger reaction and thioether oxidation using NADH as the nicotinamide cofactor.

A gene from the marine bacterium Stenotrophomonas maltophilia encodes a 38.6 kDa FAD-containing flavoprotein (Uniprot B2FLR2) named S. maltophilia flavin-containing monooxygenase (SMFMO), which catalyses the oxidation of thioethers and also the regioselective Baeyer-Villiger oxidation of the model substrate bicyclo[3.2.0]hept-2-en-6-one. The enzyme was unusual in its ability to employ either NADH or NADPH as nicotinamide cofactor. The K(M) and k(cat) values for NADH were 23.7±9.1 µM and 0.029 s(-1) and 27.3±5.3 µM and 0.022 s(-1) for NADPH. However, k(cat) /K(M) value for the ketone substrate in the presence of 100 µM cofactor was 17 times greater for NADH than for NADPH. SMFMO catalysed the quantitative conversion of 5 mM ketone in the presence of substoichiometric concentrations of NADH with the formate dehydrogenase cofactor recycling system, to give the 2-oxa and 3-oxa lactone products of Baeyer-Villiger reaction in a ratio of 5:1, albeit with poor enantioselectivity. The conversion with NADPH was 15 %. SMFMO also catalysed the NADH-dependent transformation of prochiral aromatic thioethers, giving in the best case, 80 % ee for the transformation of p-chlorophenyl methyl sulfide to its R enantiomer. The structure of SMFMO reveals that the relaxation in cofactor specificity appears to be accomplished by the substitution of an arginine residue, responsible for recognition of the 2'-phosphate on the NADPH ribose in related NADPH-dependent FMOs, with a glutamine residue in SMFMO. SMFMO is thus representative of a separate class of single-component, flavoprotein monooxygenases that catalyse NADH-dependent oxidations from which possible sequences and strategies for developing NADH-dependent biocatalysts for asymmetric oxygenation reactions might be identified.

Coccolithophores: functional biodiversity, enzymes and bioprospecting.

Emiliania huxleyi is a single celled, marine phytoplankton with global distribution. As a key species for global biogeochemical cycling, a variety of strains have been amassed in various culture collections. Using a library consisting of 52 strains of E. huxleyi and an 'in house' enzyme screening program, we have assessed the functional biodiversity within this species of fundamental importance to global biogeochemical cycling, whilst at the same time determining their potential for exploitation in biocatalytic applications. Here, we describe the screening of E. huxleyi strains, as well as a coccolithovirus infected strain, for commercially relevant biocatalytic enzymes such as acid/alkali phosphodiesterase, acid/alkali phosphomonoesterase, EC1.1.1-type dehydrogenase, EC1.3.1-type dehydrogenase and carboxylesterase.

Management of arthrofibrosis in haemophilic arthropathy.

SUMMARY: Hemophilic arthropathy is one of the conditions most associated with arthrofibrosis and loss of range of motion. Progressive fibrosis of synovium leads to pain, spasm, and shortening of muscles, resulting in joint contractures and restriction of joint motion. It is common to see even young children with severe loss of motion of elbows, knees and ankles. Treatment should be primarily by physiotherapy, splintage, and corrective devices. The late or severe cases may require surgical correction in the form of soft-tissue procedures, osteotomy and especially joint replacement.

Novel targets for antibiotic drug design.

The urgent need for new antibiotics has led to an explosion in the number and diversity of antibiotic drug targets under investigation. The majority of such targets are enzymes required for essential cellular functions. Often, such novel targets are completely unexploited for antibiotic therapy and therefore have the advantage of avoiding current resistance mechanisms. In general, the most advanced novel targets are drawn from processes where an existing antibacterial compound has validated that process for antibiotic therapy. This review describes a number of the more promising targets under development.