Interaction of GTP with proteins during the cell cycle of Streptomyces coelicolor

Abstract Six putative GTP binding proteins were detected by ultraviolet light in the presence of [α-³²P]GTP during the developmental cycle of Streptomyces coelicolor . Four out of six were true GTP binding proteins. Immunological reactions carried out with antiserum which recognizes the α-common subunit of G regulatory proteins identified two bands of 67 kDa and 30 kDa. Studies with [γ-³²P]GTP showed significant changes in protein phosphorylation during the cell cycle. The results show that at least three different systems of GTP protein interaction are present in S. coelicolor .     

ADAMTS-12 Metalloprotease Is Necessary for Normal Inflammatory Response

ADAMTSs (a disintegrin and metalloprotease with thrombospondin domains) are a family of enzymes with both proteolytic and protein interaction functions, which have been implicated in distinct pathologies. In this work, we have investigated the putative role of ADAMTS-12 in inflammation by using a mouse model deficient in this metalloprotease. Control and mutant mice were subjected to different experimental conditions to induce colitis, endotoxic sepsis, and pancreatitis. We have observed that Adamts12-deficient mice exhibit more severe inflammation and a delayed recovery from these challenges compared with their wild-type littermates. These changes are accompanied by an increase in inflammatory markers including several cytokines, as assessed by microarray expression analysis and proteomic-based approaches. Interestingly, the clinical symptoms observed in Adamts12-deficient mice are also concomitant with an elevation in the number of neutrophils in affected tissues. Finally, isolation and in vitro culture of human neutrophils demonstrate that the presence of ADAMTS-12 induces neutrophil apoptosis. On the basis of these results, we propose that ADAMTS-12 is implicated in the inflammatory response by modulating normal neutrophil apoptosis.     

Role of Periostin in Adhesion and Migration of Bone Remodeling Cells

Periostin is an extracellular matrix protein highly expressed in collagen-rich tissues subjected to continuous mechanical stress. Functionally, periostin is involved in tissue remodeling and its altered function is associated to numerous pathological processes. In orthodontics, periostin plays key roles in the maintenance of dental tissues and it is mainly expressed in those areas where tension or pressing forces are taking place. In this regard, high expression of periostin is essential to promote migration and proliferation of periodontal ligament fibroblasts. However little is known about the participation of periostin in migration and adhesion processes of bone remodeling cells. In this work we employ the mouse pre-osteoblastic MC3T3-E1 and the macrophage-like RAW 264.7 cell lines to overexpress periostin and perform different cell-based assays to study changes in cell behavior. Our data indicate that periostin overexpression not only increases adhesion capacity of MC3T3-E1 cells to different matrix proteins but also hampers their migratory capacity. Changes on RNA expression profile of MC3T3-E1 cells upon periostin overexpression have been also analyzed, highlighting the alteration of genes implicated in processes such as cell migration, adhesion or bone metabolism but not in bone differentiation. Overall, our work provides new evidence on the impact of periostin in osteoblasts physiology.     

Specific in vitro guanylylation of a 43-kilodalton membrane-associated protein of Streptomyces coelicolor.

Incubation of [alpha-32P]GTP with cellular extracts or membranes of Streptomyces coelicolor labels a protein of 43 kDa, which was also labeled with [8,5'-3H]GTP but not with [alpha-32P]ATP or [gamma-32P]GTP. Radioactivity remained associated with this protein after boiling in 0.1 N NaOH, but it was dissociated after incubation in 0.1 N HCl or hydroxylamine. Chromatographic analysis of the HCl-dissociated compound showed that GMP was the covalently bound nucleotide. Furthermore, guanylylation appeared to be reversible and to take place by a pyrophosphorylytic mechanism. Guanylylation was more efficient at low temperatures. Several Streptomyces species showed a guanylylated protein with a similar molecular mass.     

Production of propionic acid by microbiological way. Part 1. Influence of the initial sugars and product concentrations

The best yields and productivities of 0.38 g · g^?1 and 0.35 g · l^?1 h^?1, respectively, for the propionic acid production in a batchsystem using sugar-cane final molasses as carbon source were obtained when an initial TRS concentration of 50 g · l^?1 was used. It was obvious that this process is severely inhibited by the acids produced and the most drastic effect (μ = 0) was at a TVA concentration near to 250 mmol · l^?1, independently of the initial TRS concentration employed. A generalizated equation of noncompetitive inhibition was adjusted: and kinetic inhibition constants for each initial TRS concentration studied were estimated.     

Stability studies of thermophilic anaerobic sludges under suboptimal feeding conditions and temperatures

The behaviour of thermophilic anaerobic sludge from the UASB process was investigated under suboptimal conditions. Stability studies, carried out during the normal operation of the reactors, showed that a short-term decrease in temperature had no influence on the behaviour of the process. Nevertheless, interruptions in feeding and a long-term decrease in temperatures can produce very drastic effects on the stability of the system.