1. Biophysical Characterization of the Tandem FHA Domain Regulatory Module from the Mycobacterium tuberculosis ABC Transporter Rv1747.
- Author
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Heinkel, Florian, Shen, Leo, Richard-Greenblatt, Melissa, Okon, Mark, Bui, Jennifer M, Gee, Christine L, Gay, Laurie M, Alber, Tom, Av-Gay, Yossef, Gsponer, Jörg, and McIntosh, Lawrence P
- Abstract
The Mycobacterium tuberculosis ATP-binding cassette transporter Rv1747 is a putative exporter of cell wall biosynthesis intermediates. Rv1747 has a cytoplasmic regulatory module consisting of two pThr-interacting Forkhead-associated (FHA) domains connected by a conformationally disordered linker with two phospho-acceptor threonines (pThr). The structures of FHA-1 and FHA-2 were determined by X-ray crystallography and nuclear magnetic resonance (NMR) spectroscopy, respectively. Relative to the canonical 11-strand β-sandwich FHA domain fold of FHA-1, FHA-2 is circularly permuted and lacking one β-strand. Nevertheless, the two share a conserved pThr-binding cleft. FHA-2 is less stable and more dynamic than FHA-1, yet binds model pThr peptides with moderately higher affinity (∼50 μM versus 500 μM equilibrium dissociation constants). Based on NMR relaxation and chemical shift perturbation measurements, when joined within a polypeptide chain, either FHA domain can bind either linker pThr to form intra- and intermolecular complexes. We hypothesize that this enables tunable phosphorylation-dependent multimerization to regulate Rv1747 transporter activity.
- Published
- 2018