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The periplasmic substrate-binding component of an active spermidine-preferential transport system; contains the type 2 periplasmic binding fold. This group represents the periplasmic binding domain that serves as the primary polyamine receptor of ABC-type spermindine-preferential transport system from gram-negative bacteria. Polyamine transport plays an essential role in the regulation of intracellular polyamine levels which are known to be elevated in rapidly proliferating cells and tumors. Natural polyamines are putrescine, spermindine, and spermine. They are polycations that play multiple roles in cell growth, survival and proliferation, and plant stress and disease resistance. They can interact with negatively charged molecules, such as nucleic acids, to modulate their functions. Members of this family belong to the type 2 periplasmic-binding fold superfamily. PBP2 is comprised of two globular subdomains connected by a flexible hinge and bind their ligand in the cleft between these domains in a manner resembling a Venus flytrap. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",