Map30 is an anti-HIV and anti-tumor multi-functional protein extracted from the matured fruits and seeds of Momordica charantia (bitter melon). The sequence of the protein identifies MAP 30 as a member of the family of ribosomal inactivating proteins of which Ricin A is the most well known. However, Map 30 has been reported to have activities not shared by other RIPs. In order to understand its functionality at the molecular level, we have undertaken to determine its three dimensional solution structure. Although the size of the protein, 30kDa., makes this a formidable task, we have recently solved the solution structure of the protein using NMR spectroscopy, based upon ca. 4000 angle and distance constraints and 300 residual dipolar couplings. Our structure reveals that the fold of MAP 30 is quite similar to the structures of ricin A and to homologous type I RIPs whose crystal structures are available. This observation raises the question as to how MAP30 can have several distinct activities not shared by ricin A and other RIPs. A recent report (Barbieri et al. Nuc Acid Res (1997) 25, 518) suggest RIPs are generally able cleave adenine from DNA substrates. These results together with the structural information suggest that MAP30 and other type I RIPs may have similar biological activities. We are reexamining the question of the biological activity of our recombinant MAP30 samples in the light of this new information about the protein's structure.
| Wang, Y X; Neamati, N; Jacob, J et al. (1999) Solution structure of anti-HIV-1 and anti-tumor protein MAP30: structural insights into its multiple functions. Cell 99:433-42 |
| Wang, Y X; Jacob, J; Cordier, F et al. (1999) Measurement of 3hJNC' connectivities across hydrogen bonds in a 30 kDa protein. J Biomol NMR 14:181-4 |
