Title : Glycosylation of
endothelial lipase at
asparagine-116 reduces activity and the hydrolysis of native
lipoproteins in vitro and in vivo
Abstract :
- We previously identified that four of five putative N-linked glycosylation sites of human endothelial lipase ( EL ) are utilized and suggested that the substitution of asparagine-116 ( Asn-116 ) with alanine ( Ala ) (N116A) increased the hydrolytic activity of EL
- The current study demonstrates that mutagenesis of either Asn-116 to threonine ( Thr ) or Thr-118 to Ala also disrupted the glycosylation of EL and enhanced catalytic activity toward synthetic substrates by 3-fold versus wild-type EL
- Furthermore, we assessed the hydrolysis of native lipoprotein lipids by EL-N116A
- EL-N116A exhibited a 5-fold increase in LDL hydrolysis and a 1.8-fold increase in HDL2 hydrolysis
- Consistent with these observations, adenovirus-mediated expression of EL-N116A in mice significantly reduced the levels of both LDL and HDL cholesterol beyond the reductions observed by the expression of wild-type EL alone
- Finally, we introduced Asn-116 of EL into the analogous positions within LPL and HL, resulting in N-linked glycosylation at this site
- Glycosylation at this site suppressed the LPL hydrolysis of synthetic substrates, LDL, HDL2 , and HDL3 but had little effect on HL activity
- These data suggest that N-linked glycosylation at Asn-116 reduces the ability of EL to hydrolyze lipids in LDL and HDL2
Output (sent_index, trigger,
protein,
sugar,
site):
- 0. Glycosylation, , endothelial lipase, -, asparagine-116
- 1. glycosylation, , EL, -, sites
- 1. glycosylation, , endothelial lipase, -, sites
- 1. utilized, , -, -, sites
- 2. glycosylation, , EL, -, -
- 7. Glycosylation, , -, -, site
- 8. glycosylation, , -, -, Asn-116
Output(Part-Of) (sent_index,
protein,
site):
- 1. endothelial lipase, sites
- 6. EL, Asn-116
*Output_Site_Fusion* (sent_index,
protein,
sugar,
site):
- 0. endothelial lipase, -, asparagine-116
- 8. EL, -, Asn-116