Structural and Dynamic Insights into a Glycine-Mediated Short Analogue of a Designed Peptide in Lipopolysaccharide Micelles: Correlation Between Compact Structure and Anti-Endotoxin Activity.
In this study, we report an interaction study of a 13-residue analogue peptide VG13P (VARGWGRKCPLFG), derived from a designed VG16KRKP peptide (VARGWKRKCPLFGKGG), with a Lys6Gly mutation and removal of the last three residues Lys14-Gly15-Gly16, in lipopolysaccharide (LPS), a major component of the outer membrane of Gram-negative bacteria and responsible for sepsis or septic shock. VG13P displays an enhanced anti-endotoxin property as evident from significant reduction in LPS-induced TNF-α gene expression levels in a monocytic cell line, while it retains almost unchanged antimicrobial activity as its parent VG16KRKP against Gram-negative bacterial as well as fungal pathogens. In addition, in vitro LPS binding properties of VG13P in comparison to its parent VG16KRKP also remained unhindered, suggesting that the flexible C-terminal end of VG16KRKP may not play a major role in its observed antibacterial and LPS binding properties. An NMR-resolved solution structure of VG13P in LPS reveals two consecutive β-turns: one at the N-terminus, followed by another at the central region, closely resembling a rocking chair. The crucial Lys6Gly mutation along with C-terminal truncation from VG16KRKP reorients the hydrophobic hub in VG13P in a unique way so as to fold the N-terminal end back on itself, forming a turn and allowing Val1 and Ala2 to interact with Leu11 and Phe12 to bring the hydrophobic residues closer together to form a more compact hub compared to its parent. The hub is further strengthened via CH-π interaction between Gly4 and Phe12. This accounts for its improved anti-endotoxin activity as well as to its uninterrupted antimicrobial activity.
Aritreyee
A
Datta
Center of Biomedical Research , SGPGIMS Campus, Lucknow 226014, India.
Nancy
N
Jaiswal
Humaira
H
Ilyas
Shibjyoti
S
Debnath
Kaushik
K
Biswas
Center of Biomedical Research , SGPGIMS Campus, Lucknow 226014, India.
Dinesh
D
Kumar
Anirban
0000-0002-8752-2842
A
Bhunia
D000595:Amino Acid Sequence; D001419:Bacteria / Q000166:cytology / Q000187:drug effects; D002460:Cell Line; D002462:Cell Membrane / Q000187:drug effects; D015195:Drug Design; D004731:Endotoxins / Q000037:antagonists & inhibitors*; D005998:Glycine / Q000378:metabolism*; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D008070:Lipopolysaccharides / Q000737:chemistry*; D008823:Micelles; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry* / Q000494:pharmacology*; D011487:Protein Conformation; D013329:Structure-Activity Relationship
D004731:Endotoxins; D008070:Lipopolysaccharides; D008823:Micelles; D010455:Peptides; D005998:Glycine