1RH1

crystal structure of the cytotoxic bacterial protein colicin B at 2.5 A resolution

Summary for 1RH1

• Entry DOI: 10.2210/pdb1rh1/pdb
• Descriptor: Colicin B (2 entities in total)
• Functional Keywords: colicin b, fepa, cytotoxic bacterial protein, tonb, antibiotic
• Biological source: Escherichia coli
• Cellular location: Cell membrane; Multi-pass membrane protein (Potential): P05819
• Total number of polymer chains: 1
• Total formula weight: 54910.72

Authors

Hilsenbeck, J.L.,Park, H.,Chen, G.,Youn, B.,Postle, K.,Kang, C. (deposition date: 2003-11-13, release date: 2004-03-09, Last modification date: 2024-02-14)

Primary citation

Hilsenbeck, J.L.,Park, H.,Chen, G.,Youn, B.,Postle, K.,Kang, C.
Crystal structure of the cytotoxic bacterial protein colicin B at 2.5 A resolution
Mol.Microbiol., 51:711-720, 2004

PubMed Abstract: Colicin B (55 kDa) is a cytotoxic protein that recognizes the outer membrane transporter, FepA, as a receptor and, after gaining access to the cytoplasmic membranes of sensitive Escherichia coli cells, forms a pore that depletes the electrochemical potential of the membrane and ultimately results in cell death. To begin to understand the series of dynamic conformational changes that must occur as colicin B translocates from outer membrane to cytoplasmic membrane, we report here the crystal structure of colicin B at 2.5 A resolution. The crystal belongs to the space group C2221 with unit cell dimensions a = 132.162 A, b = 138.167 A, c = 106.16 A. The overall structure of colicin B is dumbbell shaped. Unlike colicin Ia, the only other TonB-dependent colicin crystallized to date, colicin B does not have clearly structurally delineated receptor-binding and translocation domains. Instead, the unique N-terminal lobe of the dumbbell contains both domains and consists of a large (290 residues), mostly beta-stranded structure with two short alpha-helices. This is followed by a single long ( approximately 74 A) helix that connects the N-terminal domain to the C-terminal pore-forming domain, which is composed of 10 alpha-helices arranged in a bundle-type structure, similar to the pore-forming domains of other colicins. The TonB box sequence at the N-terminus folds back to interact with the N-terminal lobe of the dumbbell and leaves the flanking sequences highly disordered. Comparison of sequences among many colicins has allowed the identification of a putative receptor-binding domain.

PubMed: 14731273
DOI: 10.1111/j.1365-2958.2003.03884.x

Experimental method

X-RAY DIFFRACTION (2.5 Å)