Effect of distal sugar and interglycosidic linkage of disaccharides on the activity of proline rich antimicrobial glycopeptides

Abstract

The effect of glycosylation on protein structure and function depends on a variety of intrinsic factors including glycan chain length. We have analyzed the effect of distal sugar and interglycosidic linkage of disaccharides on the properties of proline-rich antimicrobial glycopeptides, formaecin I and drosocin. Their glycosylated analogs-bearing lactose, maltose and cellobiose, as a glycan side chain on their conserved threonine residue, were synthesized where these disaccharides possess identical proximal sugar and vary in the nature of distal sugar and/or interglycosidic linkage. The structural and functional properties of these disaccharide-containing formaecin I and drosocin analogs were compared with their corresponding monoglycosylated forms, β-D-glucosyl-formaecin I and β-D-glucosyl-drosocin, respectively. We observed neither major secondary structural alterations studied by circular dichroism nor substantial differences in the toxicity with mammalian cells among all of these analogs. The comparative analyses of antibacterial activities of these analogs of formaecin I and drosocin displayed that β-D-maltosyl-formaecin I and β-D-maltosyl-drosocin were more potent than that of respective β-D-Glc-analog, β-D-cellobiosyl-analog and β-D-lactosyl-analog. Despite the differences in their antibacterial activity, all the analogs exhibited comparable binding affinity to DnaK that has been reported as one of the targets for proline-rich class of antibacterial peptides. The comparative-quantitative internalization studies of differentially active analogs revealed the differences in their uptake into bacterial cells. Our results exhibit that the sugar chain length as well as interglycosidic linkage of disaccharide may influence the antibacterial activity of glycosylated analogs of proline-rich antimicrobial peptides and the magnitude of variation in antibacterial activity depends on the peptide sequence.

Inhibition of translation termination by Drosocin, an antimicrobial peptide from fruit flies

“…Having established the mechanism of Dro action, we proceeded to define the structural features of this PrAMP critical for its ability to inhibit translation termination. Previous efforts to improve the antibiotic activity of Dro involved introduction of specific amino acid changes in its structure 33,45,46 . Some of these alterations indeed yielded derivatives with somewhat improved antibacterial properties or serum stability 45,47-49 .…”

“…Previous efforts to improve the antibiotic activity of Dro involved introduction of specific amino acid changes in its structure 33,45,46 . Some of these alterations indeed yielded derivatives with somewhat improved antibacterial properties or serum stability 45,[47][48][49] .…”

Structural basis for translation inhibition by the glycosylated antimicrobial peptide Drosocin fromDrosophila melanogaster

“…1b). In addition, we examined the previously reported (Lele et al, 2015a;Talat et al, 2011) drosocin derivatives bearing b-D-…”

“…Synthetic drosocin lacking O-glycosylation is less active than the native compounds, suggesting that the post-translational modification is necessary for full activity (Bulet et al, 1993; Bulet et al, 1999; Bulet et al, 1996; Gobbo et al, 2002; Hoffmann et al, 1999). Indeed, many studies have demonstrated that a variety of synthetic drosocin derivatives with varying sugar moieties maintain good antimicrobial activity, generally better than the unmodified form (Ahn et al, 2011a; Ahn et al, 2011b; Gobbo et al, 2002; Lele et al, 2015a; Marcaurelle et al, 1998; Otvos et al, 2000; Rodriguez et al, 1997; Talat et al, 2011). Although NMR and CD experiments suggest that both the modified and unmodified forms of drosocin adopt extended conformations in solution (Bulet et al, 1996; Gobbo et al, 2002; Lele et al, 2015a; McManus et al, 1999; Talat et al, 2011), the presence of the modification has nevertheless been proposed to help drosocin maintain an extended conformation to facilitate binding to its intracellular target (Bulet et al, 1999; Gobbo et al, 2002; McManus et al, 1999).…”

“…Indeed, many studies have demonstrated that a variety of synthetic drosocin derivatives with varying sugar moieties maintain good antimicrobial activity, generally better than the unmodified form (Ahn et al, 2011a; Ahn et al, 2011b; Gobbo et al, 2002; Lele et al, 2015a; Marcaurelle et al, 1998; Otvos et al, 2000; Rodriguez et al, 1997; Talat et al, 2011). Although NMR and CD experiments suggest that both the modified and unmodified forms of drosocin adopt extended conformations in solution (Bulet et al, 1996; Gobbo et al, 2002; Lele et al, 2015a; McManus et al, 1999; Talat et al, 2011), the presence of the modification has nevertheless been proposed to help drosocin maintain an extended conformation to facilitate binding to its intracellular target (Bulet et al, 1999; Gobbo et al, 2002; McManus et al, 1999). Additionally, glycosylation can also increase solubility, serum stability and broaden the biological activity spectrum (Bulet et al, 1999), however, the exact role of glycosylation for drosocin remains unclear.…”