About MBP / Maltose Binding Protein:
Maltose binding protein (MBP) is a complex system that involves a lot of proteins and protein complexes. It is responsible for catabolism of maltodextrins in an efficient way. Its molecular mass is approximately 42.5 kilodaltons.
Maltose binding protein is a monomeric protein that is divided into two domains. These globular domains are connected with three polypeptide segments which are short in length. The two sections are separated by a deep groove where the maltose/maltodextrin binding is stored. During the binding of maltose, there is a huge conformational change during which the groove is closed and the two sections hinge together.
Maltose Binding Protein Localization
The signal peptide of MBP serves two purposes. It slows the folding of the polypeptide and it helps it get to the membrane. Once the folding has taken place, the precursor can’t enter in the translocation pathway. This causes a residue within the core to block the export.
MBP can often prevent aggregation of certain proteins. It can also be used for purification of recombinant proteins or as an affinity tag. It can bind to amylose columns and allow other proteins to keep flowing through. It can be purified with maltose, and once purified it can be separated.
When the MBP creates a fusion protein, it can be exported to the periplasmic space and limit the number of proteins that can be recovered. It helps to create disulfide bonds like in antibody fragments. The foreign proteins that are secreted can then be exported into an E. coli periplasm with fusion. When proteins are fused with MBP, they can increase their solubility and help them fold properly.