Nucleotide sequence of a class mu glutathione S-transferase from chicken liver

A clone coding for glutathione S-transferase (GST) CL2 was isolated from a chicken liver cDNA library. This clone (819 bp) encodes a polypeptide comprising 219 amino acids with a molecular weight of 25,717, excluding the initiator methionine. The primary amino acid sequence of the enzyme has 47% identical sequence with other class mu GSTs.     

Two spatially distinct genetic elements constitute a bipartite DNA replication origin in the minute virus of mice genome.

Mutations were introduced into plasmid pMM984, a full-length infectious clone of the fibrotropic strain of minute virus of mice, to identify cis-acting genetic elements required for the excision and replication of the viral genome. The replicative capacity of these mutants was measured directly, using an in vivo transient DNA replication assay following transfection of plasmids into murine A9 cells and primate COS-7 cells. Experiments with subgenomic constructs indicated that both viral termini must be present on the same DNA molecule for replication to occur and that the viral nonstructural protein NS-1 must be provided in trans. The necessary sequences were located within 1,084 and 807 nucleotides of the 3' and 5' ends of the minute virus of mice genome, respectively. The inhibitory effect of deletions within the 206-bp 5'-terminal palindrome demonstrated that these sequences comprise a cis-acting genetic element that is absolutely essential for the excision and replication of viral DNA. The results further indicated a requirement for a stem-plus-arms T structure as well as for the formation of a simple hairpin. In addition, the removal of one copy of a tandemly arranged 65-bp repeat found 94 nucleotides inboard of the 5'-terminal palindrome inhibited viral DNA replication in cis by 10- and just greater than 100-fold in A9 and COS-7 cells, respectively. The latter results define a novel genetic element within the 65-bp repeated sequence, distinct from the terminal palindrome, that is capable of regulating minute virus of mice DNA replication in a species-specific manner.     

Viral persistence during the developmental phase of Coxsackievirus B1-induced murine polymyositis.

Mice infected with coxsackievirus B1 (CVB1) develop a chronic hindquarter muscle weakness which resembles human polymyositis. In this study, we used in situ hybridization to screen for persistent viral RNA in hamstring and quadriceps muscles from mice that displayed various degrees of clinical weakness. At 28 to 31 days postinfection, when chronic myositis is well developed but infectious virus can no longer be recovered, persistent CVB1 RNA was found in hindquarter skeletal muscle of all 12 infected animals examined. Persistent CVB1 showed a multifocal distribution within muscle and was associated with three different histopathology patterns (HPPs). These three HPPs (HPP-1, HPP-2, and HPP-3) represent potentially different stages in the mechanism of persistence. They are based on the pattern of grains, the location of hybridization signal within the muscle, and the accompanying histopathology. In HPP-1, virus persisted in nonnecrotic muscle fibers and was not directly associated with foci of inflammatory cells. HPP-2 consisted of virus contained within necrotic myocytes that were surrounded by inflammatory cells. HPP-3 was rare and showed virus inside infiltrating mononuclear cells in a region where muscle tissue had been extensively destroyed. Persistent CVB1 occurred more frequently in severely diseased animals and in tissue sections displaying intense inflammation. Moreover, HPP-2 showed a stronger association with tissue inflammation and hindquarter weakness than did HPP-1. These data demonstrate that CVB1 persists in skeletal muscle for at least 28 to 31 days postinfection and support the concept that this persistence plays a role in the development of murine polymyositis.     

Structural determinants of the factor IX molecule mediating interaction with the endothelial cell binding site are distinct from those involved in phospholipid binding

Previous studies have indicated that Factor IX/IXa interacts in a specific and high affinity manner with a binding site on the endothelial cell surface. In this study, the contributions of the gamma-carboxyglutamic acid-containing (GLA) and growth factor domains to the finding of Factor IX to the endothelium were assessed. While GLA-containing peptides from Factors IX, X, and prothrombin were inhibitors of 125I-Factor IX-endothelial cell binding, the GLA peptide from Factor IX was about 250-800-fold more effective than those from prothrombin and Factor X, respectively. In contrast to its relative efficacy as an inhibitor of Factor IX-cell surface interaction, the Factor IX-GLA peptide neither bound to lipid vesicles nor inhibited Factor IX-lipid interaction. A synthetic peptide comprising the entire first epidermal growth factor (EGF) exon was also an inhibitor of 125I-Factor IX-endothelial cell binding, although it did not interact with lipid vesicles. Experiments with synthetic peptides comprising each of the three loops of the first EGF domain or the entire first EGF region with specific substitutions indicated the importance of determinants in both the first and probably third loops for Factor IX-endothelial interaction. In contrast, the second loop of the first EGF domain and the first loop of the second EGF exon are probably not involved in Factor IX-endothelial interaction based on their inability to block 125I-Factor IX binding to cells. These results indicate that determinants in both the GLA and the first EGF domain contribute to the specific binding of Factor IX to the endothelial cell surface and that structural requirements for Factor IX-cell surface interaction are distinct from those for Factor IX binding to lipids.     

Biotransformation of thebaine by cell suspension cultures of Papaver somniferum cv. Marianne

Thebaine is biotransformed to neopine by cell suspension cultures of Papaver somniferum cv. Marianne grown in O-B5 medium. Results of precursor stu     

On the “cytosociology” of enzyme action in vivo: A novel thermodynamic correlate of biological evolution

The evolution of enzyme action in vivo is examined, in the light of established thermodynamic correlates of biological evolution. Adopting a “process” view of matter in the “living state,” the authors focus the analysis on the transition-state theory of reaction rates. Thus, the free-energy change associated with the transition-state barrier is seen as a primary target in the evolution of cellular metabolism. The utility and limitations of reductionistic approaches to enzyme evolution, based on the single enzyme, are explored first. Then, canvassing the wealth of evidence on the role of enzyme organization in vivo, the authors synthesize a “cytosociological” view of enzyme evolution. In this view, a composite (resultant) of individual transition-state barriers is deemed a more appropriate “potential function” for modification in the higher evolution of cell metabolism. The suggested direction of evolutionary changes in this function, dictated by the increasing “socialization” of enzyme action in vivo, stands as a novel postulate. This approach is shown to be completely consonant with current thinking on the thermodynamics of biological evolution, and to provide further insight into the nature of material transformations in the “living state”.     

Physical characteristics of 16 S rRNA under reconstitution conditions

The hydrodynamic shape and conformation of the 16 S ribosomal RNA in reconstitution buffer at both 4 degrees C and 37 degrees C were determined and compared with the corresponding properties of the 30 S ribosomal subunit at 4 degrees C in order to understand the role of the RNA molecule in the assembly of the 30 S subunit. At 4 degrees C, the 16 S rRNA has a sedimentation coefficient s020,w of 21.0 S, a diffusion coefficient D020,w of 1.72 X 10(-7) cm2/s, a frictional coefficient f/fmin of 2.37, and a hydrodynamic radius of 125 A. At 37 degrees C, the 16 S rRNA has a sedimentation coefficient s020,w of 18.4 S, a diffusion coefficient D020,w of 1.39 X 10(-7) cm2/s, a frictional coefficient f/fmin of 2.91, and a hydrodynamic radius of 153 A. At 4 degrees C, the 30 S subunit has a sedimentation coefficient s020,w of 31.8 S, a diffusion coefficient D020,w of 1.97 X 10(-7) cm2/s, a frictional coefficient f/fmin of 1.77, and a hydrodynamic radius of 109 A. These results suggested that the free RNA in solution at 4 degrees C is less folded than the RNA in the ribosomal subunit. At 37 degrees C, the free 16 S rRNA is unfolded when compared to the structure of the same RNA at 4 degrees C. This implies that the folding step accompanying the RI to RI transformation in the assembly process needs the presence of both the RNA and core proteins.     

Side-chain control of beta-peptide secondary structures.

As one of the most important families of non-natural polymers with the propensity to form well-defined secondary structures, the beta-peptides are attracting increasing attention. The compounds incorporating beta-amino acid residues have found various applications in medicinal chemistry and biochemistry. The conformational pool of beta-peptides comprises several periodic folded conformations, which can be classified as helices, and nonpolar and polar strands. The latter two are prone to form pleated sheets. The numerous studies that have been performed on the side-chain dependence of the stability of the folded structures allow certain conclusions concerning the principles of design of the beta-peptide foldamers. The folding propensity is influenced by local torsional, side-chain to backbone and long-range side-chain interactions. Although beta-peptide foldamers are sensitive to solvent, the systematic choice of the side-chain pattern and spatiality allows the design of the desired specific secondary structure. The application of beta-peptide foldamers may open up new directions in the synthesis of highly organized artificial tertiary structures with biochemical functions.