Function
BtuB is an outer membrane receptor found in a variety of bacteria, such as E. coli. BtuB transports vitamin B12 across the membrane of gram-negative bacteria. The transport is achieved with high affinity by the collaboration of BtuB and the periplasmic protein TonB. [1] As an essential receptor for the cell that is constitutively expressed, it is an ideal target to be parasitized, a feature exploited by a variety of proteins such as Colicins.
Structural highlights
BtuB depends on the presence of Ca+2 ions for high affinity . The .[2]
3D structure of BtuB
Updated on 18-November-2015
2guf, 1nqe, 1nqf – EcBtuB – Escherichia coli
3m8b, 3rgm, 3rgn – EcBtuB (mutant)
3m8d - EcBtuB (mutant) + cyanocobalamin
1nqh - EcBtuB + cyanocobalamin + Ca
2ysu - EcBtuB + Colicin E2 receptor binding domain
1ujw - EcBtuB + Colicin E3 receptor binding domain
2gsk - EcBtuB + TonB C-terminal
1nqg - EcBtuB + Ca
2bto – PdBtuBA + thioredoxin – Prosthecobacter dejongeii
2btq – PdBtuBA + PdBtuBB
References
- ↑ Chimento DP, Kadner RJ, Wiener MC. The Escherichia coli outer membrane cobalamin transporter BtuB: structural analysis of calcium and substrate binding, and identification of orthologous transporters by sequence/structure conservation. J Mol Biol. 2003 Oct 3;332(5):999-1014. PMID:14499604 doi:http://dx.doi.org/10.1016/S0022283603009975
- ↑ Freed DM, Horanyi PS, Wiener MC, Cafiso DS. Conformational exchange in a membrane transport protein is altered in protein crystals. Biophys J. 2010 Sep 8;99(5):1604-10. PMID:20816073 doi:10.1016/j.bpj.2010.06.026
