Deconstructing honeybee vitellogenin: novel 40 kDa fragment assigned to its N terminus.
2011
Vitellogenin, an egg-yolk protein precursor common to oviparous animals, is found abundantly in honeybee workers – a caste of helpers that do not usually lay eggs. Instead, honeybee vitellogenin (180 kDa) participates in processes other than reproduction: it influences hormone signaling, food-related behavior, immunity, stress resistance and longevity. The molecular basis of these functions is largely unknown. Here, we establish and compare the molecular properties of vitellogenin from honeybee hemolymph (blood) and abdominal fat body, two compartments that are linked to vitellogenin functions. Our results reveal a novel 40 kDa vitellogenin fragment in abdominal fat body tissue, the main site for vitellogenin synthesis and storage. Using MALDI-TOF combined with MS/MS mass-spectroscopy, we assign the 40 kDa fragment to the N terminus of vitellogenin, whereas a previously observed 150 kDa fragment corresponded to the remainder of the protein. We show that both protein units are N glycosylated and phosphorylated. Focusing on the novel 40 kDa fragment, we present a homology model based on the structure of lamprey lipovitellin that includes a conserved β-barrel-like shape, with a lipophilic cavity in the interior and two insect-specific loops that have not been described before. Our data indicate that the honeybee fat body vitellogenin experiences cleavage unlike hemolymph vitellogenin, a pattern that can suggest a tissue-specific role. Our experiments advance the molecular understanding of vitellogenin, of which the multiple physiological and behavioral effects in honeybees are well established.
* ABD
: abdominal protein extract
ACN
: acetonitrile
ConA
: concanavalin A
Degly.
: deglycosylated
HL
: hemolymph
IIS
: insulin/insulin-like signaling
JH
: juvenile hormone
LC-MS/MS
: liquid chromatography tandem mass spectrometry
MALDI-TOF/TOF
: tandem matrix-assisted laser desorption/ionization time-of-flight
MD
: molecular dynamics
S
: molecular weight standard
TFA
: trifluoroacetic acid
Vg
: vitellogenin
Keywords:
- Correction
- Source
- Cite
- Save
- Machine Reading By IdeaReader
86
References
30
Citations
NaN
KQI