Structural autonomy of a β-hairpin peptide derived from the pneumococcal choline-binding protein LytA.
The cell wall of Streptococcus pneumoniae and several other micro-organisms is decorated with a number of the so-called choline-binding proteins (CBPs) that recognise the choline residues in the bacterial surface by means of highly conserved, concatenated 20-aa sequences termed choline-binding repeats (CBRs), that are composed of a loop and a β-hairpin structure. In this work, we have investigated the ability to fold in aqueous solution of a 14-aa peptide (LytA₁₉₇₋₂₁₀[wt]) and a single derivative of it, LytA₁₉₇₋₂₁₀[ND], corresponding to one of the six β-hairpins of the LytA pneumococcal amidase. Intrinsic fluorescence and circular dichroism spectroscopical measurements showed that both peptides spontaneously acquire a non-random conformation which is also able to bind the natural ligand choline. Furthermore, nuclear magnetic resonance techniques allowed the calculation of the structure of the LytA₁₉₇₋₂₁₀[ND] peptide, which displayed a β-hairpin conformation highly similar to that found within the full-length C-LytA module. These results provide a structural basis for the modular organisation of CBPs and suggest the use of CBRs as new templates for the design of stable β-hairpins.
Instituto Universitario de Electroquímica, Universidad de Alicante, 03690-San Vicente del Raspeig.
Beatriz
B
Maestro
Clara M
CM
Santiveri
M Angeles
MA
Jiménez
Jesús M
JM
Sanz
D000581:Amidohydrolases / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D002794:Choline / Q000378:metabolism; D004795:Enzyme Stability; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D017433:Protein Structure, Secondary; D013296:Streptococcus pneumoniae / Q000737:chemistry / Q000201:enzymology*
D010455:Peptides; D000581:Amidohydrolases; C019665:amidase; D002794:Choline