title: The 1.5 A crystal structure of a prokaryote serpin: controlling conformational change in a heated environment.
abstract: Serpins utilize conformational change to inhibit target proteinases; the price paid for this conformational flexibility is that many undergo temperature-induced polymerization. Despite this thermolability, serpins are present in the genomes of thermophilic prokaryotes, and here we characterize the first such serpin, thermopin. Thermopin is a proteinase inhibitor and, in comparison with human alpha(1)-antitrypsin, possesses enhanced stability at 60 degrees C. The 1.5 A crystal structure reveals novel structural features in regions implicated in serpin folding and stability. Thermopin possesses a C-terminal "tail" that interacts with the top of the A beta sheet and plays an important role in the folding/unfolding of the molecule. These data provide evidence as to how this unusual serpin has adapted to fold and function in a heated environment.
authors.affiliation: The Protein Crystallography Unit, Department of Biochemistry and Molecular Biology, School of Biomedical Sciences, Monash University, 3800, Clayton, Australia.
authors.forename: James A
authors.initials: JA
authors.lastname: Irving
authors.forename: Lisa D
authors.initials: LD
authors.lastname: Cabrita
authors.forename: Jamie
authors.initials: J
authors.lastname: Rossjohn
authors.forename: Robert N
authors.initials: RN
authors.lastname: Pike
authors.forename: Stephen P
authors.initials: SP
authors.lastname: Bottomley
authors.forename: James C
authors.initials: JC
authors.lastname: Whisstock
mesh_terms: D000192:Actinomycetales / Q000737:chemistry*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D004795:Enzyme Stability; D006358:Hot Temperature; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011487:Protein Conformation; D011489:Protein Denaturation; D016415:Sequence Alignment; D015842:Serine Proteinase Inhibitors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015843:Serpins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000515:alpha 1-Antitrypsin / Q000737:chemistry / Q000235:genetics
chemical_list: D001426:Bacterial Proteins; D015842:Serine Proteinase Inhibitors; D015843:Serpins; D000515:alpha 1-Antitrypsin