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dictyNews Volume 34 Number 15
dictyNews
Electronic Edition
Volume 34, number 15
May 22, 2010
Please submit abstracts of your papers as soon as they have been
accepted for publication by sending them to dicty@northwestern.edu
or by using the form at
http://dictybase.org/db/cgi-bin/dictyBase/abstract_submit.
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Abstracts
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The glycopeptidome of a heavily N-glycosylated cell surface glycoprotein of
Dictyostelium implicated in cell adhesion
Christa L. Feasley, Jennifer M. Johnson, Christopher M. West, and Catherine P. Chia
Department of Biochemistry & Molecular Biology and the Oklahoma Center for Medical
Glycobiology, University of Oklahoma Health Sciences Center, Oklahoma City, OK 73104 USA;
School of Biological Sciences, University of Nebraska-Lincoln, Lincoln, NE 68588-0118 USA
J. Proteome Res., in press
Genetic analysis has implicated the cell surface glycoprotein gp130 in cell
interactions of the social amoeba Dictyostelium, and information about the
utilization of the 18 N-glycosylation sequons present in gp130 is needed
to identify critical molecular determinants of its activity. Various glycomics
strategies, including mass spectrometry of native and derivatized glycans,
monosaccharide analysis, exoglycosidase digestion and antibody binding,
were applied to characterize a non-anchored version secreted from Dictyostelium.
s-gp130 is modified by a predominant Man8GlcNAc4 species containing bisecting and
intersecting GlcNAc residues, and additional high-mannose N-glycans substituted
with sulfate, methyl-phosphate and/or core alpha3-fucose. Site mapping confirmed
the occupancy of 15 sequons, some variably, and glycopeptide analysis confirmed
14 sites and revealed extensive heterogeneity at most sites. Glycopeptide
glycoforms ranged from Man6 to Man9, GlcNAc0-2 (peripheral),
Fuc0-2 (including core alpha3 and peripheral), (SO4)0-1, and (MePO4)0-1,
which represented elements of virtually the entire known cellular N-glycome
as inferred from prior metabolic labeling and mass spectrometry studies. gp130,
and a family of 14 related predicted glycoproteins whose polypeptide sequences
are rapidly diverging in the Dictyostelium lineage, may contribute a functionally
important shroud of high-mannose N-glycans at the interface of the amoebae with
each other, their predators and prey, and the soil environment.
Submitted by Chris West [Cwest2@ouhsc.edu]
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TWO NOVEL SH2 DOMAIN PROTEINS INTERACT TO REGULATE DICTYOSTELIUM GENE EXPRESSION DURING GROWTH AND EARLY DEVELOPMENT
Christopher Sugden1, Susan Ross1, Gareth Bloomfield2, AlasdairIvens3, JasonSkelton3,Annette Mueller-Taubenberger4 and Jeffrey G. Williams1
School of Life Sciences1,Universityof Dundee, Dow St.,
Dundee DD1 5EH, UK
Wellcome Trust Sanger Institute2,
Hinxton, UK
MRC Laboratory of Molecular Biology3,
Hills Road, Cambridge, CB2 2QH, UK
Institute for Cell Biology and Center for Integrated Protein
Science4, Munich (CIPSM),
Ludwig Maximilians University, Schillerstrasse 42, D-80336
Munich, Germany
JBC, in press
There are 13 Dictyostelium SH2 domain proteins, almost ten fold fewer than in
mammals, and only three are functionally unassigned. One of these, LrrB, contains a
novel combination of protein interaction domains: an SH2 domain and a leucine-rich
repeat domain. Growth and early development appear normal in the mutant but expressionprofiling
reveals that three genes active at these stages are greatly under-expressed: the ttdA
metallo-hydrolase, the abcG10 small molecule transporter and the cinB esterase. In contrast,
the multi-gene family encoding the lectin Discoidin 1 is over-expressed in the disruptant
strain. LrrB binds to 14-3-3 protein and the level of binding is highest during growth and
decreases during early development. Comparative TAP tagging shows that LrrB also
interacts, via its SH2 domain and in a tyrosine phosphorylation dependent manner, with two
novel proteins: CldA and CldB. Both these proteins contain a Clu domain; a >200 amino
acid sequence present within highly conserved eukaryotic proteins required for correct
mitochondrial dispersal. A functional interaction of LrrB with CldA is supported by
the fact that a cldA disruptant mutant also under-expresses ttdA, abcG10 and cinB.
Significantly, CldA is itself one of the three functionally unassigned SH2 domain proteins.
Thus, just as in metazoa, but on a vastly reduced numerical scale, an interacting
network of SH2 domain proteins regulates specific Dictyostelium gene expression.
Submitted by Jeff Williams [j.g.williams@dundee.ac.uk]
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Two species of dictyostelid cellular slime molds from Alaska
Maria Romeralo, John C. Landolt, James C. Cavender, Gary A. Laursen,
and Sandie L. Baldauf.
Mycologia 2010;102 588-595.
In sampling soils to survey dictyostelid cellular slime molds in Alaska
we encountered two groups of isolates that have morphologies that differ
from any previously described species within their group. We sequenced the
nuclear small subunit ribosomal RNA gene (SSU rDNA) of selected isolates from
the two groups and found sequences from both groups to be distinct from all
previously described dictyostelid sequences. Phylogenetic analyses place one
novel species in dictyostelid Group 2 and the other in Group 4 (Schaap et al. 2006).
In this paper we formally describe as new these two species of cellular slime
molds, Dictyostelium ammophilum sp. nov. and Dictyostelium boreale sp. nov.,
based on the combination of morphological and molecular characters.
Submitted by Maria Romeralo [maria.romeralo@gmail.com]
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