title: Functional proteins from a random-sequence library.
abstract: Functional primordial proteins presumably originated from random sequences, but it is not known how frequently functional, or even folded, proteins occur in collections of random sequences. Here we have used in vitro selection of messenger RNA displayed proteins, in which each protein is covalently linked through its carboxy terminus to the 3' end of its encoding mRNA, to sample a large number of distinct random sequences. Starting from a library of 6 x 1012 proteins each containing 80 contiguous random amino acids, we selected functional proteins by enriching for those that bind to ATP. This selection yielded four new ATP-binding proteins that appear to be unrelated to each other or to anything found in the current databases of biological proteins. The frequency of occurrence of functional proteins in random-sequence libraries appears to be similar to that observed for equivalent RNA libraries.
authors: Howard Hughes Medical Institute, Department of Molecular Biology, Massachusetts General Hospital, Boston 02114, USA.
authors: A D
authors: AD
authors: Keefe
authors: J W
authors: JW
authors: Szostak
mesh_terms: D018528:ATP-Binding Cassette Transporters; D000255:Adenosine Triphosphate / Q000378:metabolism*; D000595:Amino Acid Sequence; D001665:Binding Sites; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D015723:Gene Library; D058619:Maltose-Binding Proteins; D008969:Molecular Sequence Data; D009004:Monosaccharide Transport Proteins; D019151:Peptide Library; D011485:Protein Binding; D017510:Protein Folding; D011506:Proteins / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D012313:RNA / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018528:ATP-Binding Cassette Transporters; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; D058619:Maltose-Binding Proteins; D009004:Monosaccharide Transport Proteins; D019151:Peptide Library; D011506:Proteins; D011993:Recombinant Fusion Proteins; C461599:maltose transport system, E coli; D012313:RNA; D000255:Adenosine Triphosphate