ABSTRACT
The bacterial cell wall muramyl dipeptides MDP and glucosaminyl-MDP (GMDP) are powerful immunostimulators but their binding target remains controversial. We previously reported expression cloning of GMDP-binding polypeptides and identification of Y-box protein 1 (YB-1) as their sole target. Here we show specific binding of GMDP to recombinant YB-1 protein and subcellular colocalization of YB-1 and GMDP. GMDP binding to YB-1 upregulated gene expression levels of NF-κB2, a mediator of innate immunity. Furthermore, YB-1 knockdown abolished GMDP-induced Nfkb2 expression. GMDP/YB-1 stimulation led to NF-κB2 cleavage, transport of activated NF-κB2 p52 to the nucleus, and upregulation of NF-κB2-dependent chemokine Cxcr4 gene expression. Therefore, our findings identify YB-1 as new target for muramyl peptide signaling.
Subject(s)
Acetylmuramyl-Alanyl-Isoglutamine/analogs & derivatives , Bacteria/metabolism , Cell Wall/metabolism , Immunity, Innate , Y-Box-Binding Protein 1/metabolism , Acetylmuramyl-Alanyl-Isoglutamine/metabolism , Animals , Base Sequence , Binding Sites , Cells, Cultured , DNA Primers , MiceABSTRACT
Structure-function relationship studies for novel GMDP-peptide mimic, RVPPRYHAKISPMVN (RN-peptide) were performed on array of truncated and 'Ala-scan' analogues. The shortest peptide fragment possessing detectable affinity towards anti-GMDP-antibodies was demonstrated to be PRYH. RN-peptide analogues lacking up to 8 residues at C-terminus were found to retain adjuvant activity with the minimal active peptide being RVPPRYH. Evaluation of Ala-scan analogues highlighted that adjuvant activity is most critically dependent on both arginine residues, but also is sensitive to substitution of K9, I10, S11 and M13 amino acid residues, the functional importance of which was additionally confirmed by testing peptides truncated at both termini.
Subject(s)
Adjuvants, Immunologic/chemistry , Adjuvants, Immunologic/pharmacology , Glycopeptides/chemistry , Glycopeptides/pharmacology , Structure-Activity Relationship , Amino Acid Substitution , Animals , Antibodies/blood , Enzyme-Linked Immunosorbent Assay , Mice , Mice, Inbred BALB C , Ovalbumin/administration & dosage , Ovalbumin/immunologyABSTRACT
9- and 10-membered bridged dipeptides derived from L-aspartic acid and L- or D-glutamic acid were synthesized using aminoacyl incorporation reaction. Key intermediates containing internal pyroglutamyl moiety were prepared via side chain to backbone cyclization of related protected dipeptide derivatives of glutamic acid.
Subject(s)
Aspartic Acid/chemistry , Dipeptides/chemical synthesis , Glutamic Acid/chemistry , Lactams/chemical synthesis , Bridged-Ring Compounds/chemical synthesisABSTRACT
A number of protected proline-containing dipeptides Boc-Xaa-Pro-OBu(t) were converted via epimerization-free oxidation with RuO4 to dipeptides with an internal pyroglutamic acid residue, Boc-Xaa-Glp-OBu(t). The latter were subjected to oxidative Hoffman-type rearrangement induced by PhI[OC(O)CF3]2 to give N-(aminoacyl)-pyroglutamates. The behavior of these derivatives under basic conditions was studied, and for two such a derivatives an aminoacyl incorporation reaction was observed, producing otherwise poorly accessible 10-membered-ring dilactams derived from 1,4-diaminobutyric and glutamic acids in practicable yields.
Subject(s)
Aminobutyrates/chemistry , Glutamic Acid/analogs & derivatives , Glutamic Acid/chemical synthesis , Peptides, Cyclic/chemistry , Peptides, Cyclic/chemical synthesis , Aminoacylation , Glutamic Acid/chemistry , Molecular Structure , Ornithine/chemistry , Oxidation-Reduction , Pyrrolidonecarboxylic Acid/chemistryABSTRACT
Previously unknown 9-membered bridged dipeptides derived from l or d isomers of 1,3-diaminopropionic acids and l-glutamic acid were synthesized using aminoacyl incorporation reaction. Key intermediates containing internal pyroglutamyl moiety were prepared via side chain to backbone cyclization of related protected dipeptide derivatives of glutamic acid.