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Proteolysis of truncated hemolysin A yields a stable dimerization interface
Author(s) -
Novak Walter R. P.,
Bhattacharyya Basudeb,
Grilley Daniel P.,
Weaver Todd M.
Publication year - 2017
Publication title -
acta crystallographica section f
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.572
H-Index - 37
ISSN - 2053-230X
DOI - 10.1107/s2053230x17002102
Subject(s) - antiparallel (mathematics) , tetramer , crystallography , hydrogen bond , monomer , chemistry , proteolysis , salt (chemistry) , crystal structure , stereochemistry , molecule , biochemistry , physics , organic chemistry , quantum mechanics , magnetic field , enzyme , polymer
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.