title: Evidence for PDZ domains in bacteria, yeast, and plants.
abstract: Several dozen signaling proteins are now known to contain 80-100 residue repeats, called PDZ (or DHR or GLGF) domains, several of which interact with the C-terminal tetrapeptide motifs X-Ser/Thr-X-Val-COO- of ion channels and/or receptors. PDZ domains have previously been noted only in mammals, flies, and worms, suggesting that the primordial PDZ domain arose relatively late in eukaryotic evolution. Here, techniques of sequence analysis-including local alignment, profile, and motif database searches-indicate that PDZ domain homologues are present in yeast, plants, and bacteria. It is suggested that two PDZ domains occur in bacterial high-temperature requirement A (htrA) and one in tail-specific protease (tsp) homologues, and that a yeast htrA homologue contains four PDZ domains. Sequence comparisons suggest that the spread of PDZ domains in these diverse organisms may have occurred via horizontal gene transfer. The known affinity of Escherichia coli tsp for C-terminal polypeptides is proposed to be mediated by its PDZ-like domain, in a similar manner to the binding of C-terminal polypeptides by animal PDZ domains.
authors.affiliation: Fibrinolysis Research Unit, University of Oxford, United Kingdom. Ponting@Molbiol.ox.ac.uk
authors.forename: C P
authors.initials: CP
authors.lastname: Ponting
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D001665:Binding Sites; D005656:Fungal Proteins / Q000737:chemistry* / Q000235:genetics; D022761:Gene Transfer, Horizontal; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry* / Q000235:genetics; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D005656:Fungal Proteins; D010940:Plant Proteins