Trichloroethylene oxidation by the membrane-associated methane monooxygenase in type I,type II and type X methanotrophs

Trichloroethylene (TCE) oxidation was examined in 9 different methanotrophs grown under conditions favoring expression of the membrane associated methane monooxygenase. Depending on the strain, TCE oxidation rates varied from 1 to 677 pmol/min/mg cell protein. Levels of TCE in the reaction mixture were reduced to below 40 nmolar in some strains. Cells incubated in the presence of acetylene, a selective methane monooxygenase inhibitor, did not oxidize TCE.Cultures actively oxidizing TCE were monitored for the presence of the soluble methane monooxygenase (sMMO) and membrane associated enzyme (pMMO). Transmission electron micrographs revealed the cultures always contained the internal membrane systems characteristic of cells expressing the pMMO. Naphthalene oxidation by whole cells, or by the cell free, soluble or membrane fractions was never observed. SDS denaturing gels of the membrane fraction showed the polypeptides associated with the pMMO. Cells exposed to ¹⁴C-acetylene showed one labeled band at 26 kDa, and this protein was observed in the membrane fraction. In the one strain examined by EPR spectroscopy, the membrane fraction of TCE oxidizing cells showed the copper complexes characteristic of the pMMO. Lastly, most of the strains tested showed no hybridization to sMMO gene probes. These findings show that the pMMO is capable of TCE oxidation; although the rates are lower than those observed for the sMMO.     

O-glycosylation of the mucin type

While only about ten percent of the databank entries are defined as glycoproteins, it has been estimated recently that more than half of all proteins are glycoproteins. Mucin-type O-glycosylation is a widespread post-translational modification of proteins found in the entire animal kingdom, but also in higher plants. The structural complexity of the chains initiated by O-linked GalNAc exceeds that of N-linked chains by far. The process during which serine and threonine residues of proteins become modified is confined to the cis to trans Golgi compartments. The initiation of this process by peptidyl GalNAc-transferases is ruled by the sequence context of putative O-glycosylation sites, but also by epigenetic regulatory mechanisms, which can be mediated by enzyme competition. The cellular repertoir of glycosyltransferases with their distinct donor sugar and acceptor sugar specificities, their sequential action at highly-ordered surfaces, and their localizations in subcompartments of the Golgi finally determine the cell-specific O-glycosylation profile. Dramatic alterations of the glycosylation machinery are observed in cancer cells, resulting in aberrantly O-glycosylated proteins that expose previously masked peptide motifs and new antigenic targets. The functional aspects of O-linked glycans, which comprise among many others their potential role in sorting and secretion of glycoproteins, their influence on protein conformation, and their multifarious involvement in cell adhesion and immunological processes, appear as complex as their structures.     

Evaluation of the pseudocholinesterase activity in hyperlipoproteinemia type II and type IV

Authors have evaluated pseudocholinesterase activity in patients with type IIa and type IV hyperlipoproteinemia. Significative correlation has been found between PCE and C in type IV hyperlipoproteinemia. Authors suggest PCE activity can be proposed as useful biochemical marker of hyperlipoproteinemia.     

Echovirus type 17 in the neonate

An outbreak of echovirus type 17 in a neonatal nursery with recovery of virus from the stools of the seven affected infants and the cerebrospinal fluid of one is described. Intensive nursing care and supportive therapy prevented a possible fatal outcome in all instances. A further case in another community is described in which a 5-week-old child succumbed to his illness and echovirus type 17 was isolated from autopsy tissues — lung, liver, kidney and spleen. This child had presumably received poor home care. The suggestion is made that while echovirus type 17 is not frequently associated with adult disease, it may exhibit affinity for infant tissues. This is thought to be the first time that this virus has been associated with clinical disease in a neonatal nursery and also the first account of its recovery from postmortem tissues.     

Small-molecule type III secretion system inhibitors block assembly of the Shigella type III secreton

Type III secretion systems (T3SSs) are essential virulence devices for many gram-negative bacteria that are pathogenic for plants, animals, and humans. They serve to translocate virulence effector proteins directly into eukaryotic host cells. T3SSs are composed of a large cytoplasmic bulb and a transmembrane region into which a needle is embedded, protruding above the bacterial surface. The emerging antibiotic resistance of bacterial pathogens urges the development of novel strategies to fight bacterial infections. Therapeutics that rather than kill bacteria only attenuate their virulence may reduce the frequency or progress of resistance emergence. Recently, a group of salicylidene acylhydrazides were identified as inhibitors of T3SSs in Yersinia, Chlamydia, and Salmonella species. Here we show that these are also effective on the T3SS of Shigella flexneri, where they block all related forms of protein secretion so far known, as well as the epithelial cell invasion and induction of macrophage apoptosis usually demonstrated by this bacterium. Furthermore, we show the first evidence for the detrimental effect of these compounds on T3SS needle assembly, as demonstrated by increased numbers of T3S apparatuses without needles or with shorter needles. Therefore, the compounds generate a phenocopy of T3SS export apparatus mutants but with incomplete penetrance. We discuss why this would be sufficient to almost completely block the later secretion of effector proteins and how this begins to narrow the search for the molecular target of these compounds.     

Comparison of the physicochemical properties of type I and type II iodothyronine 5'-deiodinase

The 5'-deiodination of thyroxine is catalyzed by two enzymes which differ in their tissue distribution, substrate specificities, sensitivity to the inhibitor, propylthiouracil, and response to thyroid status. By using the affinity label, N-bromoacetyl-L-thyroxine, both isoenzymes have been found to have substrate binding subunits of approximately 27 kDa. In this study, we compared the substrate binding subunits and hydrodynamic properties of the type I and the type II isozymes using the affinity label, N-bromoacetyl-L-thyroxine, to identify the enzymes. High resolution sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that the substrate binding subunit of the type I enzyme had an Mr of 27,000, while that of the type II enzyme had a slightly higher Mr of 29,000. This difference was not accounted for by glycosylation. Partial staphylococcal V8-protease digests of the substrate binding subunit of the type I enzyme yielded fragments of 14.6, 13.7, and 7.0 kDa, while V8-protease digests of the substrate binding subunit for the type II enzyme produced fragments of 28.0, 25.1, 19.0, 9.5, 7.2, and 5.8 kDa. Unique cyanogen bromide fragmentation patterns were also observed for the two substrate binding subunits. Sedimentation coefficients of the detergent-soluble type I and type II holoenzymes were 3.67 and 5.22 S, respectively, as determined by sucrose density centrifugation. The type I enzyme behaved as a globular protein, whereas the type II enzyme showed sedimentation properties typical of asymmetric integral membrane proteins. The Stokes radii were 3.78 and 4.97 nm, respectively. From these data, the calculated Mr for detergent-solubilized type I 5'-iodothyronine deiodinase was 55,400 and for the type II enzyme was 198,700. These data indicate that the two isozymes of iodothyronine 5'-deiodinase are multimeric, differ in holoenzyme size and subunit composition, and that their substrate binding subunits are distinct.     

Immunological paralysis against type 8 and immunity against type 3 Diplococcus pneumoniae induced by the soluble specific substance of type 8

Brooke, Marcus S. (Massachusetts Institute of Technology, Cambridge). Immunological paralysis against type VIII and immunity against type III Diplococcus pneumoniae induced by the soluble specific substance of type VIII. J. Bacteriol. 90:1296-1303. 1965.-Mice injected with relatively large quantities of the soluble specific substance of type VIII Diplococcus pneumoniae (SVIII) are, on the basis of challenge experiments, paralyzed against type VIII but immune against type III D. pneumoniae. Their sera contain antibodies which react with sheep cells coated with SIII. Unfortunately, it was not possible to develop an in vitro test with SVIII. When the SVIII was treated with a specific SVIII depolymerase before injection into mice, the sera still contained antibodies against SIII and some protection was afforded these mice against type III but not against type VIII challenge. When the SVIII was treated with a specific SIII depolymerase, antibodies were not detectable and the mice were not protected against type III or type VIII challenge. On the basis of these results it is suggested that either the SVIII strain is a hybrid forming both SVIII and SIII molecules or that part of the SVIII chain is altered to consist of repeating units of cellobiuronic acid rather than alternating units of cellobiuronic acid and the disaccharide galactose-glucose. The quantity of SIII in some preparations of SVIII is calculated to be of the order of 0.01%. It is not clear whether all type VIII strains at all times possess the capacity to elicit antibodies which react specifically against SIII, or if this is the property of only some strains and some preparations of these strains.     

Oto-palato-digital type I syndrome in five generations. Relationship to the type II form

Three cases of oto-palato-digital syndrome (OPD) are described. They are from the same family, in which the syndrome is an X linked recessive disorder, transmitted through five generations. These cases are classified rather in the OPD type I. The limit between OPD I and II is discussed. The hypothesis of two allelic genes is suggested.