2. Behavioral Biology TALKS - Deutsche Zoologische Gesellschaft

absence or presence of 2.000 ng/ml recombinant Hla (rHla). We also examined the
phosphorylation status and changes in subcellular localization of the focal adhesion
component paxillin in 16HBE14o- cells under rHla-treatment by quantitative Western
blotting.
rHla induced a loss of paxillin- and vinculin-positive focal adhesions in the
lamellipodia and a disorganisation of cytosolic stress fibres within the cells resulting
in changes in cell shape and reduction in cellular protrusions. These alterations
coincided with a higher phosphorylation status of paxillin on Y31 and Y118, a decline
in the amount of membrane-bound paxillin, and translocation of paxillin from the
membrane to the cytosol.
Our results indicate that rHla alters the signalling in focal adhesions, promotes the
disassembly of mature focal adhesions and prevents stabilization of native focal
contacts and formation of actin stress fibres. We conclude that such changes may
impair epithelial barrier functions in airways in early stages of an infection with
Staphylococcus aureus.
�109 Ulrich Hoeger A 704 / 14:30
Evidence for a common precursor in two Crustacean high density lipoproteins, the
large discoidal lipoprotein and the beta-glucan binding protein
Authors: Steffi Stieb 1 , Ziv Roth 2 , Isam Khalaila 2 , Amir Sagi 2 , Ulrich Hoeger 1
Affiliations: 1 Institute of Zoology, Johannes Gutenberg University, Mainz; 2 Dept of Life
Sciences and the National Institute for Biotechnology in the Negev, Ben Gurion
University, Beer Sheva, Israel
The large discoidal lipoprotein (dLP) of is a novel Crustacean hemolymph lipoprotein
only known from the decapod Astacus leptodactylus so far. Its gene and amino acid
sequence and its relationship with other lipoproteins are not yet known. To
investigate its molecular structure, MALDI-TOF measurements were carried out after
in gel digestion of the two apoproteins of the dLp. Eighteen peptides were found
matching sequences in another lipoprotein, the high density lipoprotein/?-glucan
binding protein (HDL/BGBP). These peptide fragments were located adjacent to two
putative furin cleavage sites enclosing a 1108 amino acid region of the HDL/BGBP
sequence with a calculated MW of 126 kDa. Four peptide fragments specific for the
large (280 kDa) dLp subunit were located on N-terminal side before the first furin
cleavage site, while 11 peptides specific for the small (75 kDa) subunit were found Cterminal
after the second cleavage site. No matches were found in the sequence
between the two furin sites. Our results thus suggest that the sequence of the
HDL/BGBP is also part of the dLP sequence and that both lipoproteins originate from
a common precursor which is cleaved into the BGBP and the two apoproteins of the
dLp, respectively, before lipoprotein assembly. However, the mature HDL/BGBP has a
lower molecular weight (105 kDa) than the apoprotein enclosed by the furin cleavage
sites suggesting its further processing before secretion in the hemolymph.
The presence of the same furin cleavage sites in the homologous HDL/BGBP
sequences of other decapods suggests a wider occurrence of dLP like proteins in
crustaceans.
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