Bacillus subtilis as cell factory for pharmaceutical proteins:a biotechnological approach to optimize the host organism

AbstractBacillus subtilis is a rod-shaped, Gram-positive soil bacterium that secretes numerous enzymes to degrade a variety of substrates, enabling the bacterium to survive in a continuously changing environment. These enzymes are produced commercially and this production represents about 60% of the industrial-enzyme market. Unfortunately, the secretion of heterologous proteins, originating from Gram-negative bacteria or from eukaryotes, is often severely hampered. Several bottlenecks in the B. subtilis secretion pathway, such as poor targeting to the translocase, degradation of the secretory protein, and incorrect folding, have been revealed. Nevertheless, research into the mechanisms and control of the secretion pathways will lead to improved Bacillus protein secretion systems and broaden the applications as industrial production host. This review focuses on studies that aimed at optimizing B. subtilis as cell factory for commercially interesting heterologous proteins

TNF-family member Receptor Activator of NF-$B (RANK) and RANK-Ligand (RANKL) in bone remodelling

Receptor Activator of NF-κB (RANK) and RANK-Ligand (RANKL) are members of the Tumour Necrosis Factor (TNF)-superfamily involved in bone homeostasis. In a tightly controlled interplay of this receptor and ligand, bone is continuously being remodelled. Several pathological conditions resulting from a misbalance between bone resorption and bone formation have been documented. Most frequently resorption gets the overhand resulting in a lower Bone Mineral Density (BMD), increased fracture risk and reduced mobility of patients. RANKL is expressed on bone producing osteoblasts whereas RANK is expressed on preosteoclasts, which can develop in bone resorbing osteoclasts. The binding of RANKL to RANK functions as a trigger for the formation of these bone resorbing osteoclasts. With the development of a monoclonal antibody directed against RANKL a new therapeutic strategy to interfere with bone remodelling has become available some years ago. In this manuscript we discuss the prospective of interfering with the RANK/RANKL pathway as a therapeutic target for bone diseases. We discuss the role of the soluble receptor osteoprotegerin (OPG) as a therapeutic in bone diseases. Then we focus on the possibility to develop antagonistic and agonistic variants of RANKL based on computational protein design and we discuss the development of antagonistic RANKL variants by changing the stoichiometry of the RANKL molecule

Carboxylic ester hydrolases from hyperthermophiles

Carboxylic ester hydrolyzing enzymes constitute a large group of enzymes that are able to catalyze the hydrolysis, synthesis or transesterification of an ester bond. They can be found in all three domains of life, including the group of hyperthermophilic bacteria and archaea. Esterases from the latter group often exhibit a high intrinsic stability, which makes them of interest them for various biotechnological applications. In this review, we aim to give an overview of all characterized carboxylic ester hydrolases from hyperthermophilic microorganisms and provide details on their substrate specificity, kinetics, optimal catalytic conditions, and stability. Approaches for the discovery of new carboxylic ester hydrolases are described. Special attention is given to the currently characterized hyperthermophilic enzymes with respect to their biochemical properties, 3D structure, and classification