[ PDB file ] [ PubMed link ]

The (ßa)8 barrel is one of the most common protein folds and it is thought it was one of the very first protein folds to emerge. Our collaborator Wayne Patrick previously isolated a three-quarter barrel that is soluble and almost as thermostable as full-length protein (PRAI). Our NMR structure of this three-quarter barrel shows that, despite missing a quarter of the normal foled, the subdomain is monomeric, well ordered and adopts a native-like structure in solution. These proteins - they're crazy...

[ PDB file ] [ PubMed link ]

It has been known for some time that the sidechains of several lysine residues in the transcription factor GATA1 can be modified by acetylation, but the function of these modifications has not been so clear. Our collaborator Gerd Blobel from the Children's Hospital in Philadelphia has shown that, although acetylation doesn't reduce the in vitro binding of GATA1 to DNA, acetylation of these lysines is essential for the localization of GATA1 to a chromatinized template. He more recently showed that acetylated GATA1 is recognized by Brd3. Together with Gerd, we have shown that the Brd3 bromodomain recognized a *doubly* acetylated GATA1 motif, and we have determined the structure of Brd3-bromodomain 1 bound to a GATA1 peptide containing two acetyllysine residues.

[ PDB file ] [ PubMed link ]

All GATA1-activated genes are co-occupied by LMO2, LDB1 and a number of other proteins. Here, we have used a range of NMR and mutagenesis data to create a model of the complex formed by LMO2, LDB1 and the GATA1 N-finger. Surprisingly, the model suggests that GATA1 N-finger will also be able to contact FOG1 at the same time as LMO2 and gives us more insight into the molecular details surrounding gene activation by multi-protein transcriptional assemblies.

[ PDB file ] [ PubMed link ]

All GATA1-activated genes are co-occupied by LMO2, LDB1 and a number of other proteins. As part of a project to understand how these proteins come together at such gene promoters, we have determined the solution structure of the C-terminal LIM domain of LMO2 bound to its cognate target peptide in ldb1. This domain is able to bind to the N-terminal zinc finger of GATA1 - and we have used NMR data to build a model of this complex (see above!).

[ PDB file ] [ PubMed link ]

Pathogens must steal iron from their hosts to establish infection. In mammals, hemoglobin (Hb) represents the largest reservoir of iron, and pathogens express Hb-binding proteins to access this source. Here, we show how one of the commonest and most significant human pathogens, Staphylococcus aureus, captures Hb as the first step of an iron-scavenging pathway. The x-ray crystal structure of Hb bound to a domain from the Isd (iron-regulated surface determinant) protein, IsdH, is the first structure of a Hb capture complex to be determined. Surface mutations in Hb that reduce binding to the Hb-receptor limit the capacity of S. aureus to utilize Hb as an iron source, suggesting that Hb sequence is a factor in host susceptibility to infection. The demonstration that pathogens make highly specific recognition complexes with Hb raises the possibility of developing inhibitors of Hb binding as antibacterial agents.