5 research outputs found
Biochemical Analysis of the Lipoprotein Lipase Truncation Variant, LPL<sup>S447X</sup>, Reveals Increased Lipoprotein Uptake
Lipoprotein
lipase (LPL) is responsible for the hydrolysis of triglycerides
from circulating lipoproteins. Whereas most identified mutations in
the LPL gene are deleterious, one mutation, LPL<sup>S447X</sup>, causes
a gain of function. This mutation truncates two amino acids from LPL’s
C-terminus. Carriers of LPL<sup>S447X</sup> have decreased VLDL levels
and increased HDL levels, a cardioprotective phenotype. LPL<sup>S447X</sup> is used in Alipogene tiparvovec, the gene therapy product for individuals
with familial LPL deficiency. It is unclear why LPL<sup>S447X</sup> results in a serum lipid profile more favorable than that of LPL. <i>In vitro</i> reports vary as to whether LPL<sup>S447X</sup> is
more active than LPL. We report a comprehensive, biochemical comparison
of purified LPL<sup>S447X</sup> and LPL dimers. We found no difference
in specific activity on synthetic and natural substrates. We also
did not observe a difference in the <i>K</i><sub>i</sub> for ANGPTL4 inhibition of LPL<sup>S447X</sup> relative to that of
LPL. Finally, we analyzed LPL-mediated uptake of fluorescently labeled
lipoprotein particles and found that LPL<sup>S447X</sup> enhanced
lipoprotein uptake to a greater degree than LPL did. An LPL structural
model suggests that the LPL<sup>S447X</sup> truncation exposes residues
implicated in LPL binding to uptake receptors
We FRET so You Don’t Have To: New Models of the Lipoprotein Lipase Dimer
Lipoprotein lipase
(LPL) is a dimeric enzyme that is responsible
for clearing triglyceride-rich lipoproteins from the blood. Although
LPL plays a key role in cardiovascular health, an experimentally derived
three-dimensional structure has not been determined. Such a structure
would aid in understanding mutations in LPL that cause familial LPL
deficiency in patients and help in the development of therapeutic
strategies to target LPL. A major obstacle to structural studies of
LPL is that LPL is an unstable protein that is difficult to produce
in the quantities needed for nuclear magnetic resonance or crystallography.
We present updated LPL structural models generated by combining disulfide
mapping, computational modeling, and data derived from single-molecule
Förster resonance energy transfer (smFRET). We pioneer the
technique of smFRET for use with LPL by developing conditions for
imaging active LPL and identifying positions in LPL for the attachment
of fluorophores. Using this approach, we measure LPL–LPL intermolecular
interactions to generate experimental constraints that inform new
computational models of the LPL dimer structure. These models suggest
that LPL may dimerize using an interface that is different from the
dimerization interface suggested by crystal packing contacts seen
in structures of pancreatic lipase
We FRET so You Don’t Have To: New Models of the Lipoprotein Lipase Dimer
Lipoprotein lipase
(LPL) is a dimeric enzyme that is responsible
for clearing triglyceride-rich lipoproteins from the blood. Although
LPL plays a key role in cardiovascular health, an experimentally derived
three-dimensional structure has not been determined. Such a structure
would aid in understanding mutations in LPL that cause familial LPL
deficiency in patients and help in the development of therapeutic
strategies to target LPL. A major obstacle to structural studies of
LPL is that LPL is an unstable protein that is difficult to produce
in the quantities needed for nuclear magnetic resonance or crystallography.
We present updated LPL structural models generated by combining disulfide
mapping, computational modeling, and data derived from single-molecule
Förster resonance energy transfer (smFRET). We pioneer the
technique of smFRET for use with LPL by developing conditions for
imaging active LPL and identifying positions in LPL for the attachment
of fluorophores. Using this approach, we measure LPL–LPL intermolecular
interactions to generate experimental constraints that inform new
computational models of the LPL dimer structure. These models suggest
that LPL may dimerize using an interface that is different from the
dimerization interface suggested by crystal packing contacts seen
in structures of pancreatic lipase
We FRET so You Don’t Have To: New Models of the Lipoprotein Lipase Dimer
Lipoprotein lipase
(LPL) is a dimeric enzyme that is responsible
for clearing triglyceride-rich lipoproteins from the blood. Although
LPL plays a key role in cardiovascular health, an experimentally derived
three-dimensional structure has not been determined. Such a structure
would aid in understanding mutations in LPL that cause familial LPL
deficiency in patients and help in the development of therapeutic
strategies to target LPL. A major obstacle to structural studies of
LPL is that LPL is an unstable protein that is difficult to produce
in the quantities needed for nuclear magnetic resonance or crystallography.
We present updated LPL structural models generated by combining disulfide
mapping, computational modeling, and data derived from single-molecule
Förster resonance energy transfer (smFRET). We pioneer the
technique of smFRET for use with LPL by developing conditions for
imaging active LPL and identifying positions in LPL for the attachment
of fluorophores. Using this approach, we measure LPL–LPL intermolecular
interactions to generate experimental constraints that inform new
computational models of the LPL dimer structure. These models suggest
that LPL may dimerize using an interface that is different from the
dimerization interface suggested by crystal packing contacts seen
in structures of pancreatic lipase
We FRET so You Don’t Have To: New Models of the Lipoprotein Lipase Dimer
Lipoprotein lipase
(LPL) is a dimeric enzyme that is responsible
for clearing triglyceride-rich lipoproteins from the blood. Although
LPL plays a key role in cardiovascular health, an experimentally derived
three-dimensional structure has not been determined. Such a structure
would aid in understanding mutations in LPL that cause familial LPL
deficiency in patients and help in the development of therapeutic
strategies to target LPL. A major obstacle to structural studies of
LPL is that LPL is an unstable protein that is difficult to produce
in the quantities needed for nuclear magnetic resonance or crystallography.
We present updated LPL structural models generated by combining disulfide
mapping, computational modeling, and data derived from single-molecule
Förster resonance energy transfer (smFRET). We pioneer the
technique of smFRET for use with LPL by developing conditions for
imaging active LPL and identifying positions in LPL for the attachment
of fluorophores. Using this approach, we measure LPL–LPL intermolecular
interactions to generate experimental constraints that inform new
computational models of the LPL dimer structure. These models suggest
that LPL may dimerize using an interface that is different from the
dimerization interface suggested by crystal packing contacts seen
in structures of pancreatic lipase