Taxonomic distribution of proteins containing GA domains

The tree below includes only several representative species and genera. The complete taxonomic breakdown of all proteins containing GA domains can be accessed here. Click the counts or percentage values to display the corresponding proteins.

Solution structure of the albumin-binding GA module: a versatile bacterialprotein domain.

Johansson MU, de Chateau M, Wikstrom M, Forsen S, Drakenberg T, Bjorck L
J Mol Biol. 1997; 266: 859-65

The albumin-binding GA module is found in a family of surface proteins ofdifferent bacterial species. It comprises 45 amino acid residues andrepresents the first known example of contemporary module shuffling. Using1H NMR spectroscopy we have determined the solution structure of the GAmodule from protein PAB, a protein of the anaerobic human commensal andpathogen Peptostreptococcus magnus. This structure, the firstthree-dimensional structure of an albumin-binding protein domaindescribed, was shown to be composed of a left-handed three-helix-bundle.Sequence differences between GA modules with different affinities foralbumin indicated that a conserved region in the C-terminal part of thesecond helix and the flexible sequence between helices 2 and 3 couldcontribute to the albumin-binding activity. The effect on backbone amideproton exchange rates upon binding to albumin support this assumption. TheGA module has a fold that is strikingly similar to theimmunoglobulin-binding domains of staphylococcal protein A but it shows noresemblance to the fold shared by the immunoglobulin-binding domains ofstreptococcal protein G and peptostreptococcal protein L. When the genesequences, binding properties and thermal stability of these four domainsare analysed in relation to their global folds an evolutionary patternemerges. Thus, in the evolution of novel binding properties mutations areallowed only as long as the energetically favourable global fold ismaintained.