dictyNews
Electronic Edition
Volume 48, number 14
July 29, 2022
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=========
Abstracts
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Oxygen-dependent regulation of E3(SCF)ubiquitin ligases and a
Skp1-associated JmjD6 homolog in development of the social
amoeba Dictyostelium
Andrew W. Boland (1,2), Elisabet Gas-Pascual (1,2,3), Braxton L.
Nottingham (4,5), Hanke van der Wel (1,4), M. Osman Sheikh (4,6),
Christopher M. Schafer (4,7), Christopher M. West (1,2,3,4,8)
1 Dept. of Biochemistry & Molecular Biology, 2 Complex Carbohydrate
Research Center, 3 Center for Tropical and Emerging Global Diseases,
University of Georgia, Athens, GA 30602, 4 Dept. of Biochemistry &
Molecular Biology, University of Oklahoma Health Sciences Center,
Oklahoma City, OK 73104 USA
5 Current address: Integris Health Medical Group Cross Timbers,
Edmond OK 73034 USA
6 Current address: Amicus Therapeutics, Philadelphia, PA USA
7 Current address: Cardiovascular Biology Research Program,
Oklahoma Medical Research Foundation, 825 N.E. 13th Street,
Oklahoma City, OK 73104 USA
8 to whom requests for information or materials should be sent:
Dept. of Biochemistry & Molecular Biology, 120 E. Green St., Davison
Life Sciences – B129, University of Georgia, Athens GA 30602 USA,
telephone +1-706-542-4259, email [log in to unmask]
J. Biol. Chem., in press
E3-SCF (Skp1/cullin-1/F-box protein) polyubiquitin ligases activate the
proteasomal degradation of over a thousand proteins, but the evolutionary
diversification of the F-box protein (FBP) family of substrate receptor
subunits has challenged their elucidation in protists. Here we expand the
FBP candidate list in the social amoeba Dictyostelium and show that the
Skp1 interactome is highly remodeled as cells transition from solitary growth
to multicellular development. Importantly, a subset of candidate FBPs was
less represented when the posttranslational hydroxylation and glycosylation
of Skp1 was abrogated by deletion of the O2 -sensing Skp1 prolyl hydroxylase
PhyA. A role for this Skp1 modification for SCF activity was indicated by partial
rescue of development, which normally depends on high O2 and PhyA, of
phyA -knockout cells by proteasomal inhibitors. Further examination of two
FBPs, FbxwD and the Jumonji C protein JcdI, suggested that Skp1 was
substituted by other factors in phyA-knockout cells. Although a double-knockout
of jcdI and its paralog jcdH did not affect development, overexpression of JcdI
increased its sensitivity to O2. JcdI, a non-heme dioxygenase shown to have
physiological O2-dependence, is conserved across protists with its F-box and
other domains, and related to the human oncogene JmjD6. Sensitization of
JcdI-overexpression cells to O2 depended on its dioxygenase activity and other
domains, but not its F-box, which may however be the mediator of its reduced
levels in wild-type relative to Skp1 modification mutant cells. The findings
suggest that activation of JcdI by O2 is tempered by homeostatic down-
regulation via PhyA and association with Skp1.
Submitted by Chris West [[log in to unmask]]
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[End dictyNews, volume 48, number 14]
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