title: Replacing the (beta alpha)-unit 8 of E.coli TIM with its chicken homologue leads to a stable and active hybrid enzyme.
abstract: In order to investigate how structural modifications interfere with protein stability, we modified a (beta alpha)-unit in E.coli triosephosphate isomerase (TIM), a typical (beta alpha)-barrel protein, assuming that the pseudosymmetrical beta-barrel can be divided into eight successive loop/beta-strand/loop/alpha-helix motifs. We replaced the eighth (beta alpha)-unit of E.coli TIM with the corresponding chicken (beta alpha)-unit. The substitution, involving the replacement of 10 of the 23 residues of this (beta alpha)-unit, was evaluated first by modelling, then experimentally. Modelling by homology suggests how the amino acid replacements might be accommodated in the hybrid E.coli/chicken TIM (ETIM8CHI). Both natural and hybrid recombinant TIMs, overproduced in E.coli, were purified to homogeneity and characterized as to their stability and kinetics. Our kinetic studies show that the modification performed here leads to an active enzyme. The stability studies indicate that the stability of ETIM8CHI is comparable to that of the wild type TIM.
authors.affiliation: Laboratoire de Biologie Moléculaire et de Génie Génétique, Université de Liège, Sart Tilman, Belgium.
authors.forename: V
authors.initials: V
authors.lastname: Mainfroid
authors.forename: K
authors.initials: K
authors.lastname: Goraj
authors.forename: F
authors.initials: F
authors.lastname: Rentier-Delrue
authors.forename: A
authors.initials: A
authors.lastname: Houbrechts
authors.forename: A
authors.initials: A
authors.lastname: Loiseau
authors.forename: A C
authors.initials: AC
authors.lastname: Gohimont
authors.forename: M E
authors.initials: ME
authors.lastname: Noble
authors.forename: T V
authors.initials: TV
authors.lastname: Borchert
authors.forename: R K
authors.initials: RK
authors.lastname: Wierenga
authors.forename: J A
authors.initials: JA
authors.lastname: Martial
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002645:Chickens / Q000235:genetics; D004795:Enzyme Stability; D004926:Escherichia coli / Q000201:enzymology / Q000235:genetics; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D015202:Protein Engineering; D017510:Protein Folding; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D014305:Triose-Phosphate Isomerase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D011993:Recombinant Fusion Proteins; D014305:Triose-Phosphate Isomerase