The Three-Dimensional Structure of Pectate Lyase E, a Plant Virulence Factor from Erwinia chrysanthemi.
The three-dimensional structure of pectate lyase E (PelE) has been determined by crystallographic techniques at a resolution of 2.2 A. The model includes all 355 amino acids but no solvent, and refines to a crystallographic refinement factor of 20.6%. The polypeptide backbone folds into a large right-handed cylinder, termed a parallel [beta] helix. Loops of various sizes and conformations protrude from the central helix and probably confer function. A putative Ca2+-binding site as well as two cationic sites have been deduced from the location of heavy atom derivatives. Comparison of the PelE and recently determined pectate lyase C (PelC) structures has led to identification of a putative polygalacturonate-binding region in PelE. Structural differences relevant to differences in the enzymatic mechanism and maceration properties of PelE and PelC have been identified. The comparative analysis also reveals a large degree of structural conservation of surface loops in one region as well as an apparent aromatic specificity pocket in the amino-terminal branch. Also discussed is the sequence and possible functional relationship of the pectate lyases with pollen and style plant proteins.
Lietzke
S. E.
SE
Department of Biochemistry (S.E.L., M.D.Y., F.J.), and Department of Plant Pathology (N.T.K.), University of California, Riverside, California 92521.
Yoder
M. D.
MD
Keen
N. T.
NT
Jurnak
F.
F