Structural and functional studies of Afa/Dr family adhesin proteins from pathogenic E. coli and their receptors

Diffusely adhering Escherichia coli (DAEC) is a bacterial pathotype that causes enteric and urinary tract infections.DAEC possesses adhesive structure called fimbriae/afimbriae for adherence to host receptors, which is essential for the following invasion.The typical class of DAEC including E. coli strains harbouring adhesins such as AfaE-I, AfaE-II, AfaE-III and Dr, form the fimbriae/afimbriae via a polymeric architectures.AfaE-III recognizes the glycophosphatidylinositol (GPI) Canchored protein Decay-Accelerating Factor (DAF, CD55) and CEA (CD66e) as receptors.The docking complex models of AfaE/CEA and AfaE/DAF have been determined from mutagenesis and NMR-derived restraints.The solution structure of AafA, which is an AfaE homologue from Enteroaggregative E. coli (EAEC) has also been determined by multidimensional NMR techniques.The AfaE/CEA complex model reveals that the binding interface on the N-CEA is partially overlapped with N-CEA dimerisation interface.It has been found that the AfaE adhesin does not bind to a covalently linked N-CEA dimer, which is close to its native form.Binding kinetics, mutational analysis and spectroscopic examination of CEA dimers suggest that Dr adhesin can dissociate CEA dimers prior to the binding of monomeric forms.The Afa/DAF complex model implies the AfaE binds to domains CCP2 First of all I would like to express my sincere gratitude to my supervisor, Prof Steve J. Matthews, who is a significant presence in my study and also my life.Thank you for giving me the opportunity to start my Ph.D course, during which you provided me numerous invaluable suggestions and constructive advice during the course.Your zeal for science, sports and life inspired my mind and your tireless diligence will encourage me throughout the rest of life.Furthermore I am deeply indebted to Dr. Ernesto Cota Segura.Without his patience and support, I could not even start this project.You shared valuable experiences with me and also taught me how to solve the new problems.You are much more than a project co-supervisor to me.I thank Dr. Pete J. Simpson, the NMR guru.Thank you for your guidance through my whole project.I always wish that I could have half of your knowledge of both NMR spectroscopy and alcohols.I thank the people in the Matthews lab, past