An intramolecular switch regulates phosphoindependent FHA domain interactions in Mycobacterium tuberculosis

Timothy J. Nott, Geoff Kelly, Lasse Stach, Jiejin Li, Sarah Westcott, Dony Patel, Debbie M. Hunt, Steven Howell, Roger S. Buxton, Helen M. O'Hare, Stephen J. Smerdon

Research output: Contribution to journalArticlepeer-review

71 Scopus citations


Forkhead-associated (FHA) domains have gained considerable prominence as ubiquitous phosphothreonine-dependent binding modules; however, their precise roles in serine and threonine kinase (STK) pathways and mechanisms of regulation remain unclear. From experiments with Rv1827, an FHA domain-containing protein from Mycobacterium tuberculosis, we derived a complete molecular description of an FHA-mediated STK signaling process. First, binding of the FHA domain to each of three metabolic enzyme complexes regulated their catalytic activities but did not require priming phosphorylation. However, phosphorylation of a threonine residue within a conserved amino-terminal motif of Rv1827 triggered its intramolecular association with the FHA domain of Rv1827, thus blocking its interactions with each of the three enzymes. The solution structure of this inactivated form and further mutagenic studies showed how a previously unidentified intramolecular phosphoswitch blocked the access of the target enzymes to a common FHA interaction surface and how this shared surface accommodated three functionally related, but structurally diverse, binding partners. Thus, our data reveal an unsuspected versatility in the FHA domain that allows for the transformation of multiple kinase inputs into various downstream regulatory signals.

Original languageEnglish
Pages (from-to)ra12
JournalScience Signaling
Issue number63
StatePublished - 24 Mar 2009
Externally publishedYes


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