Asymmetric states of vitamin B-12 transporter BtuCD are not discriminated by its cognate substrate binding protein BtuF

作者：Korkhov Vladimir M; Mireku Samantha A; Hvorup Rikki N; Locher Kaspar P^*

来源：FEBS LETTERS, 2012, 586(7): 972-976.

DOI：10.1016/j.febslet.2012.02.042

• Membrane protein
• ABC transporter
• BtuCDF
• Periplasmic binding protein
• Asymmetry
• X-ray structure

BtuCD is an ABC transporter catalyzing the uptake of vitamin B-12 across the Escherichia coli inner membrane. A previously reported X-ray structure of BtuCD in complex with the periplasmic vitamin B-12-binding protein BtuF revealed asymmetry of the transmembrane BtuC subunits. The functional relevance of this asymmetry has remained uncertain. Here we report the X-ray structure of a catalytically impaired BtuCD mutant in complex with BtuF, where the BtuC subunits adopt a distinct asymmetric conformation. The structure suggests that BtuF does not discriminate between, or impose, asymmetric conformations of BtuCD. It also explains the conformational disorder observed in BtuCDF crystals.
Structured summary of protein interaction

• 出版日期2012-4-5