title: Proteolysis of truncated hemolysin A yields a stable dimerization interface.
abstract: Wild-type and variant forms of HpmA265 (truncated hemolysin A) from Proteus mirabilis reveal a right-handed, parallel β-helix capped and flanked by segments of antiparallel β-strands. The low-salt crystal structures form a dimeric structure via the implementation of on-edge main-chain hydrogen bonds donated by residues 243-263 of adjacent monomers. Surprisingly, in the high-salt structures of two variants, Y134A and Q125A-Y134A, a new dimeric interface is formed via main-chain hydrogen bonds donated by residues 203-215 of adjacent monomers, and a previously unobserved tetramer is formed. In addition, an eight-stranded antiparallel β-sheet is formed from the flap regions of crystallographically related monomers in the high-salt structures. This new interface is possible owing to additional proteolysis of these variants after Tyr240. The interface formed in the high-salt crystal forms of hemolysin A variants may mimic the on-edge β-strand positioning used in template-assisted hemolytic activity.
authors.affiliation: Department of Chemistry, Wabash College, 301 West Wabash Avenue, Crawfordsville, IN 47933, USA.
authors.forename: Walter R P
authors.initials: WR
authors.lastname: Novak
authors.affiliation: Department of Chemistry and Biochemistry, University of Wisconsin-La Crosse, 1725 State Street, La Crosse, WI 54601, USA.
authors.forename: Basudeb
authors.initials: B
authors.lastname: Bhattacharyya
authors.affiliation: Department of Chemistry and Biochemistry, University of Wisconsin-La Crosse, 1725 State Street, La Crosse, WI 54601, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Grilley
authors.affiliation: Department of Chemistry and Biochemistry, University of Wisconsin-La Crosse, 1725 State Street, La Crosse, WI 54601, USA.
authors.forename: Todd M
authors.initials: TM
authors.lastname: Weaver
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D003001:Cloning, Molecular; D018360:Crystallography, X-Ray; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006460:Hemolysin Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006860:Hydrogen Bonding; D008958:Models, Molecular; D009154:Mutation; D010957:Plasmids / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D059748:Proteolysis; D011513:Proteus mirabilis / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D006460:Hemolysin Proteins; D011994:Recombinant Proteins
keywords: Proteus mirabilis; alternate crystal forms; hemolysin A; proteolysis; two-partner secretion; β-helix