Mechanistic basis of Vitamin B12 and cobinamide salvaging by the Vibrio species

Publication date: Available online 18 November 2018Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Shubhangi Agarwal, Sanjay Dey, Biplab Ghosh, Maitree Biswas, Jhimli DasguptaAbstractBiosynthesis of vitamin B12, which occurs through salvaging pathway or de novo synthesis, is essential for the survival and growth of bacteria. While the mechanism is known for many bacteria, it is elusive yet for diarrhea causing pathogenic bacteria Vibrio cholerae or the other Vibrio species. Sequence analysis using genome databases delineated that majority of the Vibrio species including V. cholerae contain genes required for salvaging cobalamin/cobinamide in aerobic pathway while lack the genes required for de novo synthesis of B12. Fluorescence quenching study showed that VcBtuF, the PBP of putative ABC transporter BtuF-CD of V. cholerae O395 binds cyanocobalamin and dicyanocobinamide with micromolar dissociation constants (Kd). Productive internalization of these nutrients has been established through growth assay. The crystal structure of cyanocobalamin bound VcBtuF has shown that although interactions between cyanocobalamin and VcBtuF are largely similar to E. coli BtuF, VcBtuF possesses a wider binding pocket. MD simulations indicated that in contrast to EcBtuF that executes ‘open-close’ movement, inter-lobe twisting is prevalent in VcBtuF. Although H70, located at the entrance of the substrate binding cleft of VcBtuF, executes swinging motion, it cann...
Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - Category: Biochemistry Source Type: research