4H0F

Mutant Structure of laminin-binding adhesin (Lmb) from Streptococcus agalactiae

Summary for 4H0F

• Entry DOI: 10.2210/pdb4h0f/pdb
• Related: 3HJT
• Descriptor: Laminin-binding surface protein, ZINC ION (3 entities in total)
• Functional Keywords: adhesin, human laminin, cell adhesion
• Biological source: Streptococcus agalactiae
• Total number of polymer chains: 2
• Total formula weight: 59316.10

Authors

Karthe, P.,Preethi, R. (deposition date: 2012-09-08, release date: 2013-09-04, Last modification date: 2023-09-13)

Primary citation

Ragunathan, P.,Sridaran, D.,Weigel, A.,Shabayek, S.,Spellerberg, B.,Ponnuraj, K.
Metal binding is critical for the folding and function of laminin binding protein, Lmb of Streptococcus agalactiae.
Plos One, 8:e67517-e67517, 2013

PubMed Abstract: Lmb is a 34 kDa laminin binding surface adhesin of Streptococcus agalactiae. The structure of Lmb reported by us recently has shown that it consists of a metal binding crevice, in which a zinc ion is coordinated to three highly conserved histidines. To elucidate the structural and functional significance of the metal ion in Lmb, these histidines have been mutated to alanine and single, double and triple mutants were generated. These mutations resulted in insolubility of the protein and revealed altered secondary and tertiary structures, as evidenced by circular dichroism and fluorescence spectroscopy studies. The mutations also significantly decreased the binding affinity of Lmb to laminin, implicating the role played by the metal binding residues in maintaining the correct conformation of the protein for its binding to laminin. A highly disordered loop, proposed to be crucial for metal acquisition in homologous structures, was deleted in Lmb by mutation (ΔLmb) and its crystal structure was solved at 2.6 Å. The ΔLmb structure was identical to the native Lmb structure with a bound zinc ion and exhibited laminin binding activity similar to wild type protein, suggesting that the loop might not have an important role in metal acquisition or adhesion in Lmb. Targeted mutations of histidine residues confirmed the importance of the zinc binding crevice for the structure and function of the Lmb adhesin.

PubMed: 23826314
DOI: 10.1371/journal.pone.0067517

Experimental method

X-RAY DIFFRACTION (2.4 Å)