Anchoring of proteins to lactic acid bacteria

The anchoring of proteins to the cell surface of lactic acid bacteria (LAB) using genetic techniques is an exciting and emerging research area that holds great promise for a wide variety of biotechnological applications. This paper reviews five different types of anchoring domains that have been explored for their efficiency in attaching hybrid proteins to the cell membrane or cell wall of LAB. The most exploited anchoring regions are those with the LPXTG box that bind the proteins in a covalent way to the cell wall. In recent years, two new modes of cell wall protein anchoring have been studied and these may provide new approaches in surface display. The important progress that is being made with cell surface display of chimaeric proteins in the areas of vaccine development and enzyme- or whole-cell immobilisation is highlighted.

Ribosome Display Selection of a Murine IgG1 Fab Binding Affibody Molecule Allowing Species Selective Recovery Of Monoclonal Antibodies

Affinity reagents recognizing constant parts of antibody molecules are invaluable tools in immunotechnology applications, including purification, immobilization, and detection of immunoglobulins. In this article, murine IgG1, the primary isotype of monoclonal antibodies (mAbs) was used as target for selection of novel binders from a combinatorial ribosome display (RD) library of 1011 affibody molecules. Four rounds of selection using three different mouse IgG1 mAbs as alternating targets resulted in the identification of binders with broad mIgG1 recognition and dissociation constants (KD) in the low nanomolar to low micromolar range. For one of the binders, denoted Zmab25, competition in binding to full length mIgG1 by a streptococcal protein G (SPG) fragment and selective affinity capture of mouse IgG1 Fab fragments after papain cleavage of a full mAb suggest that an epitope functionally overlapping with the SPG-binding site in the CH1 domain of mouse IgG1 had been addressed. Interestingly, biosensor-based binding experiments showed that neither human IgG1 nor bovine Ig, the latter present in fetal bovine serum (FBS) was recognized by Zmab25. This selective binding profile towards murine IgG1 was successfully exploited in species selective recovery of two different mouse mAbs from complex samples containing FBS, resembling a hybridoma culture supernatant

Early diagenesis and isotopic composition of lead in Lake Laisan, northern Sweden

Water column (dissolved/suspended phase, sediment traps) and sediment data (pore-water, solid-phase sediment) were combined with stable Pb and Pb-210 isotope data to trace the early diagenetic behaviour and geochemical cycling of Pb in Lake Laisan, a lake which has received large quantities of anthropogenic Pb since the early 1940s. Early diagenetic remobilisation of Pb is indicated by a subsurface pore-water Pb maximum (120 mug 1(-1)) in the oxic surface layer of the sediment, where the solid-phase Pb concentration is 3400-4600 mug g(-1). The remobilisation of Pb appears to be caused by a pH-controlled desorption of Pb from solid-phase sediment, which is consistent with a model describing surface complexation of Pb(II) on hydrous goethite surfaces. The diffusive Pb flux from the subsurface pore-water maximum towards the sediment surface (36 mug cm(-2) year(-1)) exceeds the depositional Pb flux (8.6 mug cm(-2) year(-1)) by approximately a factor of four, indicating that Pb is highly mobile in the sediment. Stable Pb isotope data and a mass balance calculation suggest that Pb diffusing upwards is, to a large extent, trapped in the surface sediment. Lead that may diffuse into the slightly alkaline lake water appears to be efficiently sorbed to suspended particulate matter, resulting in low dissolved Pb concentrations in the water column (0.040-0.046 mug 1(-1)). Sorption of Pb to suspended particulate matter is consistent with the elevated suspended particulate Pb concentrations in the hypolimnion (3800-4000 mug g(-1)), and the fact that the stable Pb isotopic compositions of suspended matter and pore-water are similar